Proceedings of the 6th International Conference on Improving Energy Efficiency in
Commercial Buildings: IEECB Focus 2010 13th - 14th of April, 2010, Frankfurt am Main (Germany)
Editors: Angelica MARINO, Paolo BERTOLDI
EUR 24465 EN - 2010
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Proceedings of the 6th International Conference on Improving Energy Efficiency in Commercial Buildings: IEECB Focus 2010 13th – 14th April 2010, Frankfurt am Main (Germany) Editors: Angelica MARINO, Paolo BERTOLDI
EUR 24465 EN - 2010
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Executive summary Buildings are large consumers of energy and consequently responsible for a big share of green house gas emissions. The electricity consumption of the tertiary and residential sectors represented 57% of the total energy consumption in EU-27 2007. Moreover, from 1990 to 2007 the final energy consumption of the building sector grew 12%, while the electricity consumption in the building sector grew 53% during the same timeline. The strong development of the tertiary sector, particularly in the New Member States, has a considerable influence on the growing energy consumption. Furthermore, it is estimated that ca. 20% of the worldwide electric energy consumption is used for lighting. The electricity consumption used for lightning is estimated to grow by 2-3%/year in developed countries. Energy conservation and the application of energy efficient measures has increasingly become a focus of the building industry as a means of mitigating the environmental impacts of energy consumption, reducing building operating costs as energy costs escalate, raising the propriety value and attracting more selective tenants. Moreover, improving energy efficiency offers the largest and most cost effective mitigation opportunities in the buildings sector. A broad range of best practice examples demonstrates that it is possible to achieve up to 80% energy savings at low or no extra costs. However, despite an increased awareness of commercial buildings energy consumption and the options and positive financial performance of energy efficiency measures for propriety developers and owners, the adoption of energy conserving and efficiency measures is lower than expected. Studies shows that the energy consumption of buildings is generally underestimated, while the costs of energy efficiency and energy conservation measures are generally considerably overestimated. Furthermore, the Principal-Agent dilemma present in the building sector due to the distance between the propriety developer and propriety owner and the energy consumer (the tenant, who pays the energy costs) makes investment decisions in energy conservation and efficiency measures complex. Following the success of the previous IEECB conferences1, Messe Frankfurt with the scientific collaboration of the European Commission Joint Research Centre organised the sixth International conference on Improving Energy Efficiency in Commercial Buildings (IEECB’10). The sixth IEECB’10 took place on the 13th and 14th of April, 2010 in Frankfurt during Light+Building, the International Trade Fair for Architecture and Technology in Frankfurt, Germany. The IEECB'10 brought together players from the sector, including commercial buildings’ investors and property managers, energy efficiency experts, equipment manufacturers, service providers (ESCOs, utilities, facilities management companies) and policy makers. IEECB'10 provided a forum for the participants for knowledge and experience sharing for learning about the latest development in the sector and of course, for networking. The two days conference offered two session tracks, one session track focused on programmes, policies, and best practice and a second track more technology oriented with the presentation of stateof-the-art equipment and systems. Stakeholders' decision criteria in energy efficiency investment and the market based instruments and economic barriers were analysed together with the relevant legislative framework of the building sector. A number of programmes and policies were analysed, such as the GreenLight programme, the European Energy Service Initiative and SELINA. Studies of the electricity consumption in the European service sector were also presented as tools and models for the analysis of energy consumption in buildings and the impact of energy conservation measures. State-of-the-art equipment and systems were introduced such as lighting technology, HVAC auxiliary equipment, ICT & office equipment. It emerged from the conference that a lack in understanding of the relevance of energy consumption in buildings is coupled with a lack of confidence in adopting energy conserving and energy efficient 1
IEECB’98 in Amsterdam, IEECB’02 in Nice, IEECB’04, and IEECB’06 and IEECB'08 in Frankfurt. 3
measures. Nevertheless, interest is still growing for energy efficient solutions. A stricter regulatory framework (such as energy efficiency building codes and labelling standards) is needed to increase the demand for energy conservation and efficiency solutions on the market. On the other hand, the interest for and the impact of voluntary programmes is stronger where organisations voluntary commit to reduce their energy consumption by adopting energy conservation and efficient measures (such as the GreenBuilding programme). It is hoped that the availability of this compendium will enable a large audience to benefit from the presentations made at the conference. Potential readers who may benefit from this book include energy and environment researchers, engineers and equipment manufacturers, policy makers, energy agencies and energy efficiency programme managers, energy supply companies, energy regulatory authorities. We hope the conference proceedings will be a valuable contribution to disseminate information and best practices in policies, programmes and technologies to foster the penetration of highly efficient buildings in the commercial sector. The Editors, Angelica Marino Paolo Bertoldi
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Contents Policies and Programmes Energy Efficiency in Buildings – The WBCSD’s Call to Action 11 William M. Sisson1, Constant Van Aerschot2 Co-Chairs, Energy Efficiency in Buildings Project, World Business Council for Sustainable Development 1 United Technologies Corporation, 2Lafarge Evaluation of the European Greenlight Programme 2000-2008 16 Paolo Bertoldi1, Rita Werle1,2, Vassilios KARAVEZYRIS1,3, Perry SEBASTIAN4 1 EUROPEAN COMMISSION JOINT RESEARCH CENTRE, 2A+B International, Switzerland, 3Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, GERMANY, 4Capella university Reducing Energy Consumption and Peak Demand in Commercial Buildings Iris Sulyma and Ken Tiedemann BC Hydro, Vancouver, Canada
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Decarburizing Hungarian tertiary buildings through improved energy efficiency: technological options, costs and the CO2 mitigation potential 39 Victoria Novikova Central European University, Centre for Climate Change and Sustainable Energy Policy Energy savings potential in the Hungarian public buildings for space heating Katarina Korytarova and Diana Ürge-Vorsatz Central European University EESI – European Energy Service Initiative: Challenges and Chances for Energy Performance Contracting in Europe Susanne Berger Berliner Energieagentur GmbH
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Building Portfolio Energy Analysis – Optimization Procedure Samir E. Chidiac1, H. Lynn Perry1, Simon Foo2 and Edward Morofsky2 1 Department of Civil Engineering, McMaster University, Canada 2 Real Property Branch HQ, Public Works & Government Services Canada
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Legislative Framework of Building Sector Energy Efficiency in Turkey Ebru Acuner, Sermin Onaygil, Emre Erkin Energy Planning and Management Division, Energy Institute, Istanbul Technical University
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IEECB'10 - Barriers, Financing & Risk Analysis A Framework for Estimating and Communicating the Financial Performance of Energy Efficiency Improvements in Existing Commercial Buildings While Considering Risk and Uncertainty Alireza Bozorgi1,2 (Ph.D. Candidate in Design Research), James R. Jones1 (Associate Professor of Architecture) 1 College of Architecture and Urban Studies, 2Pamplin College of Business Virginia Polytechnic Institute and State University
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Calculating life cycle cost in the early design phase to encourage energy efficient and sustainable buildings 104 Gerhard Hofer1, Bernhard Herzog2, Margot Grim1 1 e7 Energie Markt Analyse GmbH, 2M.O.O.CON GmbH Economic barriers to low-carbon office refurbishments Giuseppe Pellegrini-Masini1, Dr David Jenkins1, Gary McLaren2, Dr Graeme Bowles1, Ross Buchan2 1 Heriot-Watt University, 2Thomson Bethune
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The importance and the impact of economic, organizational, cultural and social goals of companies and institutions for commercial buildings 126 Martin Pongratz, Thorsten Speer M.O.O.CON How to overcome the socio-economic obstacles for efficient energy use in Smart buildings – and opportunities to save energy through efficient interoperability with the Smart grid Volker Dragon Siemens Switzerland Ltd.
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The Impact of Stakeholder Decision Criteria on Global Carbon Abatement in the Building Sector 138 Kevin Otto1, Christian Kornevall2, William Sisson3 1 Robust Systems and Strategy LLC, 2The World Business Council for Sustainable Development, 3United Technologies Corporation IEECB'10 - HVAC New Liquid Desiccant Cooling Systems for Buildings: Performance and Applications Joan Carles Bruno, Joan Carles Esteban, Núria Quince, Alberto Coronas Universitat Rovira i Virgili, Mechanical Engineering Dept., CREVER – Research Group on Applied Thermal Engineering
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Morphological implications of passive techniques in office buildings architecture. Luca Finocchiaro1, Tore Wigenstad2, Anne Grete Hestnes1 1 Department of Architectural Design, History and Technology, NTNU 2 Sintef Building and Infrastructure, Trondheim
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Assessing the energy performance of HVAC systems in the tertiary building sector by on-site monitoring 169 Marco Masoero, Chiara Silvi, Jacopo Toniolo Dipartimento di Energetica - Politecnico di Torino Image Processing for Overnight Lighting Quantification in Buildings Dr Neil Brown Institute of Energy and Sustainable Development, De Montfort University.
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HYDRONIC HEATING, VENTILATING AND AIR CONDITIONING - Energy-conscious solutions for building occupant comfort 195 Tim Ashton, LEED AP, B.Sc. (Hons.) Physics for Advanced Technology Carrier Air Conditioning, Europe, Middle-East & Africa A Systematic Optimization and Operation of Central Chilling Systems for Energy Efficiency and Sustainability 208 Zhenjun Ma and Shengwei Wang Department of Building Services Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China Evaluation of energy savings related to building envelope retrofit techniques and ventilation strategies for low energy cooling in offices and commercial sector 218 Laurent Grignon-Massé, Dominique Marchio, MINES ParisTech Marco Pietrobon, Lorenzo Pagliano, Politecnico di Milano - Energy Department - End-use Efficiency Research Group HARMONAC: Quantifying the Energy Conservation Opportunities in Air-Conditioning Inspections as required by EPBD Article 9 233 Ian Knight and James Cambray Welsh School of Architecture, Cardiff University, Cardiff, UK Maximizing Refrigeration Efficiency in New Commercial Buildings Ken Tiedemann and Iris Sulyma BC Hydro, Vancouver, Canada
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Heat Pumping and Reversible Air Conditioning in Office buildings Philippe ANDRE1 and Jean LEBRUN2 1 University of Liège, Department of Environmental Sciences and Management 2 JCJ Energetics
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IEECB'10 - Energy Efficiency in Building Equipment Technology forecast in Lighting regarding Energy Efficiency Wilfried Pohl Bartenbach LichtLabor
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Theoretical Comparison of Innovative Window Daylighting Devices for a sub-tropical climate using Radiance Michael Hirning, Veronica Garcia Hansen, John Bell Queensland University of Technology
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Thermo-accumulation: an effective alternative for increasing the power load factor in electricity retailing 286 1,2 Vieira, Francisco Anizio; Frota, 2Maurício Nogueira, and 2Souza, Reinaldo Castro 1 Asea Brown Boveri, ABB 2 Postgraduate Metrology Programme Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil Elevators and escalators: Energy performance and Strategies to promote energy efficiency Anibal de Almeida1, Elisabeth Dütschke2, Carlos Patrao1, Simon Hirzel2, João Fong1 1ISR-University of Coimbra, Portugal 2Fraunhofer ISI, Karlsruhe, Germany
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Standby and off-mode energy losses in office equipment - The SELINA project 311 Aníbal de Almeida1, Andrea Roscetti2, Lorenzo Pagliano2, Barbara Schlomann3, Carlos Patrão4, David Silva5, Philippe Rivière5 1 ISR-University of Coimbra - eERG, end-use Efficiency Research Group, 2Dipartimento di Energia, Politecnico di Milano, 3Fraunhofer ISI, 4ISR-University of Coimbra, 5Mines Paristech MICROPOLYGENERATION APPLICATIONS FOR MILD CLIMATE Sergio Sibilio 1, Carlo Roselli2, Maurizio Sasso2 1 Built Environment Control Laboratory - Seconda Università degli Studi di Napoli, Italy 2 DING Università degli Studi del Sannio, Italy Keywords: Trigeneration, Thermochemical Accumulator, gas fuelled engine, experimental plant IEECB'10
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Success Examples & Retrofits
Energy Efficiency in Historic Buildings, the case study of the National Theatre of Rhodes, Greece and of the Zena Castle, Italy 341 Maria Kikira a, Elena Gigliarelli b a Architect, Department of Buildings, Division of Energy Efficiency, Centre for Renewable Energy Sources and Saving-CRES, Greece and researcher, University College London Energy Institute, UK b Architect, CNR - ITABC Institute of Technology Applied to Cultural Heritage, Italy What Really Makes Buildings Efficient: Results from the Low Energy High Rise Project Paul Bannister1, Chris Bloomfield1, Michael Porter1, Sue Salmon2, Robert Mitchel2, Robert Quinn3 1 Exergy Australia, 2The Warren Centre, University of Sydney, 3National Project Consultants
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Bringing all parties to the table: overcoming barriers to energy efficiency in the world’s most famous building 364 Paul Rode (Director, Business Development), Kelly Smith (Sustainability Programs Manager) Johnson Controls Reducing Energy Consumption and Peak Demand in Commercial Buildings Iris Sulyma and Ken Tiedemann
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BC Hydro, Vancouver, Canada Façade Zone in relation to Energy, Indoor Environment and Cost in office buildings 382 Maria Kikira a, Harry Bruhns b a Architect, BSc, MSc, Department of Buildings, Division of Energy Efficiency, Centre for Renewable Energy Sources and Saving-C.R.E.S., and researcher, UCL Energy Institute, University College London, UK b Principal Research Fellow, UCL Energy Institute, University College London, UK IEECB'10 - Building Energy Rating & Commissioning Signs of Hope? Emerging trends in European Building Performance from an analysis of DISPLAY Richard Bull, Ashish Shukla, Graeme Stuart Institute of Energy and Sustainable Development, De Montfort University.
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The Future of Building Energy Rating and Disclosure Mandates: What Europe Can Learn From the United States 405 Andrew Burr1, Cliff Majersik1, Nick Zigelbaum2 1 Institute for Market Transformation, 2 Natural Resources Defence Council Measurement and simulation of a commercial building in Norway Matthias Haase, Catherine Grini, and Tore Wigenstad NTNU, Department of Architectural Design, History and Technology SINTEF Building and Infrastructure, Buildings department, energy and environment group
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Persistence of benefits maintained over ten years of on-going commissioniong at the CanmetENERGY Building using a BEMS Assisted Commissioning Tool 430 Daniel Choinière, P.Eng. CanmetENERGY, Natural Resources Canada Development and application of ongoing commissioning methods and tools for non-residential buildings in German and European research programs 441 Nicolas Réhault, Christian Neumann, Dirk Jacob Fraunhofer Institut Solare Energiesysteme – Freiburg - Germany IEECB'10 - Success Examples & Monitoring Nachhaltigkeit Massiv - Scientific fundamentals for the further development of solid building Fechner Johannes1, Hofer Gerhard2 1 17&4 Organisationsberatung GmbH, 2e7 Energie Markt Analyse GmbH
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Image Processing for Overnight Lighting Quantification in Buildings Dr Neil Brown, Institute of Energy and Sustainable Development, De Montfort University
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Retrofit of an Office Building with Passive Cooling – REB Remscheid Dipl.-Ing. Peter Engelmann, Prof. Dr.-Ing. Karsten Voss Bergische Universität Wuppertal, Department of Architecture Buildings Physics and Building Services
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How client project process knowledge and involvement improves the overall performance of commercial buildings – Unfallkasse Hessen, a case study 487 Andreas Leuchtenmüller, Martin Pongratz, Thorsten M. Speer M.O.O.CON IEECB'10 - Building Energy Management Systems eDIANA: a new architectural approach for ICT-enabled energy efficient buildings Rafael Socorro1, José Javier de las Heras1, Janne Peltonen2 1 Research and Development Department, ACCIONA Infraestructures S.A. 2 Building Services and Indoor Environment, VTT Technical Research Centre of Finland
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Multi agent building study on the control of the energy balance of an aquifer Olaf van Pruissen and René Kamphuis Unit Efficiency and Infrastructure, Energy Research Centre of the Netherlands
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Energy Efficient Operation of Existing Buildings Through Simulation Based Control Optimisation Dirk Pietruschka, Andreas Biesinger, Andreas Trinkle, Ursula Eicker Centre for Applied Research of Sustainable Energy Technologies - zafh.net at the University of Applied Sciences in Stuttgart
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HosPilot, Intelligent Energy Efficiency Control in Hospitals 531 Manuel Fernández1, Régis Decorme2, Manuel Ramiro1, Nebojsa Fisekovic3, Santiago Erice4, Borja Tellado5 . Mikko Gröndahl6, Aurélia Delclos7, Esa Nykänen8, André Hundt9 1 Acciona, 2CSTB, 3Philips Lighting, 4Philips Iberica, 5Labein, 6Granlund, 7Enoleo 8VTT), 9UMCG IEECB'10 - Monitoring Energy Consumption Survey and analysis of the energy consumption of a sample of office buildings and retail facilities Dario AIULFI1, Martin JAKOB2, Alex PRIMAS3 1 Sorane SA, 2TEP Energy GmbH, 3Basler&Hofmann AG
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Energy Consumption in Non-Domestic Buildings Richard Kilpatrick, Professor Phillip Banfill Heriot-Watt University
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Regular survey on energy consumption in the tertiary sector in Germany Barbara Schlomann1, Edelgard Gruber2, Bernd Geiger3, Heinrich Kleeberger3, Till Herzog4 1 Fraunhofer Institute for Systems and Innovation Research (Fraunhofer ISI), 2IREES 3 , IfE-Technical University Munich, 4GfK Marketing Services
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An in-deep analysis of the electricity end-use consumption and energy efficiency trends in the tertiary sector of the European Union 582 Paolo Bertoldi, Bogdan Atanasiu European Commission Joint Research Centre, Institute for Energy Electricity demand in the European service sector: A detailed bottom-up estimate by sector and by enduse 604 Tobias Fleiter1, Simon Hirzel1, Martin Jakob2, Jan Barth1, Laura Quandt3, Felix Reitze3, Felipe Toro3, Martin Wietschel1 1 Fraunhofer Institute for Systems and Innovation Research (ISI), Karlsruhe 2 TEP Energy GmbH, Zurich 3 Institute for Resource Efficiency and Energy strategies (IREES GmbH), Karlsruhe
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Policies and Programmes
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Energy Efficiency in Buildings – The WBCSD’s Call to Action William M. Sisson1, Constant Van Aerschot2 Co-Chairs, Energy Efficiency in Buildings Project, World Business Council for Sustainable Development 1 United Technologies Corporation, 2Lafarge
Abstract In 2006, the World Business Council for Sustainable Development (WBCSD) launched its Energy Efficiency in Buildings (EEB) project under the co-leadership of Lafarge and United Technologies Corporation. Twelve multi-national firms joined to make up the Core Group and together put forward three phases of effort documented in two reports and a manifesto. In 2007, the EEB summarized the building sector’s principle facts and trends in their “Business Realities and Opportunities” report; and, in 2009 the EEB provided its 6 interdependent recommendations towards achieving a radical departure from business as usual in its landmark “Transforming the Market” report. Crucial in the EEB reported findings is to unleash mechanisms that would lead to a transformative market response towards increased energy efficiency and corresponding CO2 emissions reductions from the design, retrofit and operation of buildings. This transformative response is critical towards achieving the 6080% sector wide reductions called for under the IPCC’s stabilization scenarios. For its third and final phase of the EEB project the President of the WBCSD, in October 2009, called upon its 205 member company CEO’s to measure, manage, and report the energy and emissions of their buildings. The declarations outlined in this call to action are the WBCSD’s Manifesto for Energy Efficiency in Buildings. The Manifesto outlines five distinct actions: First, to measure and set a baseline for buildings; next, to set internal policies and reduction targets to reduce energy and emissions from these buildings, and then to report the measures and results publicly. The final action is to promote internal and external advocacy for the Manifesto and its intentions, to employees, suppliers, and external stakeholders in order to increase the awareness and support for efficiency improvements and corresponding CO2 reductions in buildings. The Manifesto Implementation Guide was drafted as a supporting guideline, prepared by the EEB Core Group, and outlines to its members how to implement the five actions in an effective way. The Manifesto is intended to reinforce the principle findings of the EEB’s work – to raise awareness and mobilize the market, and to stimulate transformative demand through transparency, standards, and codes. It will promote action among the WBCSD members to achieve measurable results within the building stock it controls, to demonstrate leadership and drive the market mechanisms needed to launch the transformation.
Introduction Buildings are large consumers of energy and consequently the largest emitters of green house gas emissions of all sectors in almost all developed and developing economies. Most professionals in the building sector are not aware of this fact. Further, the complexity of the sector is such that it handles a series of transactions that often distance the real consumer from the choices that could minimize consumption. In 2006, under the auspices of the World Business Council for Sustainable Development (WBCSD), two leading firms in the building supply chain set out to understand these challenges. Together with 12 other multinational firms, the Energy Efficiency in Buildings (EEB) project was launched. The project identified the critical levers of holistic design, financial mechanisms, and behavior as critical ingredients for change, augmented by effective regulatory and political structures to effectively transform the industry. Further, through bottom up quantitative analysis combined with a top down qualitative scenario assessment, the project identified six key recommendations that are essential to transform the market by 2050, such that the calls for significant reductions in energy use
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and corresponding CO2 emissions can be realized for the sector. However, to show a commitment to action from the business community sponsoring this work, more was needed – and the concept of the Manifesto for Energy Efficient Buildings was launched. Building sector professionals have little incentive to change. The market doesn’t demand energy efficiency, there is a no transparency required for a building’s energy, and there are not enough effective regulatory and political structures in place to push the market towards increased level of energy responsibility and CO2 management in building codes. In fact, a survey of market professionals undertaken by the WBCSD’s EEB project team uncovered a startling conundrum – building professionals underestimate the impact of buildings on energy and carbon by 50% and overestimate the cost to deliver energy efficiency and sustainable buildings by over 300%.In the same survey, building professionals identified financiers, developers, contractors, regulators, and owners as the top 5 participants that were the barriers towards transformation. Without addressing the barriers, the market will go on behaving business-as-usual and a vicious circle of blame will ensue, as depicted in Figure 1.
The vicious circle of blame
Source: David Cadman, Center for the Study of Sustainable Building: The Carbon Challenge, 2007
Figure 1 The Vicious Circle of Blame Decision Makers Influence the Outcome Buildings are delivered through a number of decision makers – those whose profits are guaranteed by the tendering process and the lowest cost provider downstream in the process. As shown in Figure 2, this spans from the architects under contract by developers to the occupiers who establish leases from the owners. Energy efficiency is an avoidable cost, undervalued by the market, and one that requires no transparency or code adherence in the transaction – beyond a minimum level of achievement set forward by outdated standards and practices developed before the current energy and climate crisis we now face. Energy cost is a small fraction of a buildings operational cost and rarely does the energy condition of a building enter the contractual dialog; often foreshadowed by location, building aesthetics, and convenience compounded by lease or capital cost in short term horizons.
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Source: WBCSD Energy Efficiency in Buildings, Facts & Trends Full Report (2007), Perception Study
Figure 2 The Complexity of Decision Makers in the Buildings Sector After careful evaluation of this market, the EEB project team realized the market would need a stimulus – one in which pushed the recommendations of its landmark study forward without waiting for the political structures to come forward. The EEB Manifesto sets out to be that market stimulus – to take the WBCSD’s 200 strong multi-national corporations forward on a declaration to demand energy efficient buildings in the market. In only one month after its release, nearly 25% of the WBCSD members had signed onto the Manifesto, indicative of the interest towards transforming the market. To EEB In Action group of the WBCSD intends to achieve a 75% acceptance by the end of 2010. Model Based Recommendations The EEB study concluded the market would transform to reach 80% reductions by 2050 only if a game-changing departure occurs from the building sectors traditional practices. Through a rigorous bottom up modelling approach combined with top down scenarios, the project concluded that a comprehensive set of mechanisms would be needed for transformation. Modelling of decision criteria undertaken in the bottom up model, showed five startling results: 1. 2. 3. 4. 5.
Markets will not adopt attractive solutions without tight regulatory structures Rational price signals had surprisingly low effect, particularly carbon pricing Integrated/coordinated technical approaches were most effective Implicitly, the principle-agent problem must be overcome and mind-set is key Market response will be distinguished by local economic and cultural characteristics
With appropriate mechanisms, the modeling showed that decision makers associated with new and existing buildings in commercial and residential markets could drive a market response towards the needed 60-80% reductions in energy use and corresponding CO2 emissions. The modeled decisions were economically attractive with favorable returns, in excess of 10% rates of return, for at least 50% of the needed reductions – that is if taken in a holistic manner. From these results, the project put forward the following recommendations depicted in Figure 3: 1. Create and enforce building energy efficiency codes and labeling standards a. Extend current codes and tighten over time b. Display energy performance labels c. Conduct energy inspections and audits 2. Incentivize energy-efficient investments a. Establish needed price signals and use tax incentives, subsidies and creative financial models to lower first-cost hurdles 3. Encourage integrated design approaches and innovations a. Improve contractual terms to promote integrated design teams b. Incentivize integrated team formation 4. Fund energy savings technology development programs
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a. Accelerate rates of efficiency improvement for energy technologies b. Improve building control systems to fully exploit energy saving opportunities 5. Develop workforce capacity for energy saving a. Create and prioritize training and vocational programs b. Develop “system integrator” profession 6. Mobilize for an energy-aware culture a. Promote behaviour change and improve understanding across the sector b. Businesses and governments lead by acting on their building portfolios
Figure 3 The WBCSD EEB Mutually Supported Recommendations
The WBCSD’s Call to Action – Manifesto for EEB For its third and final phase of the EEB project the President of the WBCSD, in October 2009, called upon its 205 member company CEO’s to measure, manage, and report the energy and emissions of their buildings. The declarations outlined in this call to action are the WBCSD’s Manifesto for Energy Efficiency in Buildings as shown in Figure 4. The Manifesto outlines five distinct actions: First, to measure and set a baseline for buildings; next, to set internal policies and reduction targets to reduce energy and emissions from these buildings, and then to report the measures and results publicly. The final action is to promote internal and external advocacy for the Manifesto and its intentions, to employees, suppliers, and external stakeholders in order to increase the awareness and support for efficiency improvements and corresponding CO2 reductions in buildings. A Manifesto Implementation Guide was drafted as a supporting guideline, prepared by the EEB Core Group, and outlines to its members how to implement the five actions in an effective way. The Manifesto is intended to reinforce the principle findings of the EEB’s work – to raise awareness and mobilize the market, and to stimulate transformative demand through transparency, standards, and codes. It will promote action among the WBCSD members to achieve measurable results within the building stock it controls, to demonstrate leadership and drive the market mechanisms needed to launch the transformation. In an unprecedented response, one-quarter of WBCSD’s members signed onto the Manifesto within a month of the initial request. The WBCSD is aggressively targeting that 75% of its members will be signed by the end of 2010. With this level of subscription to the Manifesto, a combined economic force of nearly $4 trillion in market turnover and $5 trillion in market capitalization and would be achieved and used as market leverage for transformation towards higher levels of energy efficient
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buildings in the market. At this level, the aggregated WBCSD voice for increased volume of energy efficient buildings, both new and for lease, would provide a substantially diverse and significantly strong market signal towards fixing the market failures underlying the major decision maker’s resistance to transformation.
Figure 4 The WBCSD Manifesto for EEB
References [1]
World Business Council for Sustainable Development, Energy Efficiency in Buildings Project, Facts and Trends, Business Realities and Opportunities; Summary Report, October 2007.
[2]
World Business Council for Sustainable Development, Energy Efficiency in Buildings Project, Transforming the Market, April 2009.
[3]
World Business Council for Sustainable Development, Manifesto for Energy Efficiency in Buildings, November, 2009.
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Evaluation of the European Greenlight Programme 2000-2008 Paolo Bertoldi1, Rita Werle1,2, Vassilios KARAVEZYRIS1,3, Perry SEBASTIAN4 1 2 3 EUROPEAN COMMISSION JOINT RESEARCH CENTRE, A+B International, Switzerland, Federal 4 Ministry for the Environment, Nature Conservation and Nuclear Safety, GERMANY, Capella university
Abstract This paper is a summary of the main findings of the evaluation of the GreenLight Programme, a voluntary non-residential energy efficiency programme of the European Commission. The GreenLight Programme aims at stimulating increased investment into efficient lighting in a visible manner. The paper reports on how successful the GreenLight Programme was during the period 2000-2008 and includes recommendations for the future. These recommendations could serve well for other voluntary energy efficiency programmes. The result of the evaluation is that the GreenLight Programme was very successful during the assessed period. The network of Partners was continuously expanding reaching 519 Partners by the end of 2008. Out of this, 90 Partners coming from the New Member States of the European Union joined between 2006-2008. New GreenLight gave an impetus to the promotion of the GreenLight Programme. It was launched in 2006 aiming to expand the GreenLight Programme to the New Member States of the European Union. In total, Partners saved 241 GWh/year by the end of 2008 which corresponds to a saving of around 24 million EUR in running costs. From the total, almost 60 GWh/year was saved by Partners coming from the New Member States. One GreenLight Partner saved 689 MWh/year on the average, or 35.99% compared to the level of energy consumption before introducing energy saving measures. As for technology, savings were achieved through lamp conversions and the use of lighting controls. In the case of interior lighting, changing mercury vapour lamps or fluorescent T8 tubes to fluorescent T5 tubes accounted for 23% of the assessed energy savings. Converting metal halide lamps to compact fluorescent lamps generated a further 10% saving. In the case of outdoor lighting, changing mercury vapour lamps to high pressure sodium lamps meant a saving of 13% of all the reported technology savings. By using lighting controls, Partners saved 18% within the total reported energy savings, attributable to technological changes. The rest of the savings is linked to other lamp conversions. Based on Partners’ responses to the survey, their major motivation for joining the GreenLight Programme was to reduce energy use and cut costs. More than 80% of the Partners were satisfied with the results of the lighting efficiency project, and in general with the GreenLight Programme as a whole. 14% of the respondents stated that they would have not introduced energy efficiency measures without the GreenLight Programme. Partners strongly encouraged further promotion of the GreenLight Programme both within their network and towards the public. The GreenLight Programme shall be promoted on a wider scale through different channels (e.g. internet, television, technical literature, conferences, seminars, etc.). Programme administration could be facilitated with web-based tools, making online application and reporting possible. A requirement for remaining a Partner on the long term could be to maintain the lighting system energy efficient by regular upgrades, keeping pace with the advancements of lighting technology.
1. Introduction To convince end-users to adopt efficient lighting technologies and systems and achieve a long lasting market transformation, the European Commission launched in 2000 the European GreenLight Programme ("GreenLight Programme"). It has been designed to promote energy efficiency in non-
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residential lighting, based on a voluntary participation. The GreenLight Programme is managed by the Joint Research Centre of the European Commission (“Joint Research Centre”). Any European public or private organisation can join the GreenLight Programme as a Partner (“Partner”) or as an Endorser (“Endorser”). Partners commit themselves to upgrading the lighting system in their existing facilities or to install best available efficient lighting systems in their new buildings2. Endorsers are promoting the GreenLight Programme to potential Partners, and are providing assistance to Partners especially in the implementation of the energy saving measures [EGL2009]. The benefit of Partners and Endorsers in joining the GreenLight Programme is a wide public recognition for their efforts to improve lighting efficiency within their organisation. National Contact Points3 have been appointed in each participating country to provide information and assistance to (potential) Partners and Endorsers present in their country. They constitute a bridge between the main GreenLight Programme administration, and the (potential) programme participants. The Joint Research Centre made a comprehensive evaluation of the results of the GreenLight Programme from its start in 2000 until the end of 2008. This paper gives an overview on the main findings, structured as follows: • Analysis of the composition and savings of Partners: how the number of Partners and their energy savings evolved from 2000 in the participating countries. • Analysis of changes in the applied technology, which is the source of the savings: which part of the energy savings can be attributed to a certain type of technology change. • Analysis of the motivations for and the benefits of joining the GreenLight Programme.
2. Methods Partner organisations who commit to the GreenLight Programme report on their savings and the changes in technology to the Joint Research Centre. This information served as the basis of the analysis. To evaluate the motivation of Partners for joining the GreenLight Programme and their experiences as a GreenLight Partner, a survey was conducted among the Partners. The period assessed is from 2000 to 20084. The assessment was carried out using spreadsheet analysis (Excel). Energy savings were analysed as in total (e.g. total GreenLight Programme savings) and per Partner (average and relative5 savings). Savings were assessed according to countries and along sectoral categories. These categories were created taking into account the business area of the Partners in the first place but also the project type implemented. As the energy savings were reported by the Partners themselves, this imposes some limitations on the results. First of all, there are more than 100 Partners with no information on their savings. Most of them did not report on their savings, others did report but the savings could not be extracted from their report. Secondly, some Partners' figures seemed inconsistent, or incomplete, which after further enquiries could be corrected, but not in all cases. Thus data which could not be justified has been excluded from the assessment, to avoid any incongruities. In the end, for 169, thus more than 30% of the Partners there is no adequate data available on the energy savings. The extent of information provided on the savings by Partners differs which means that different subgroups of Partners were assessed with regard to total savings, relative savings and changes in technology. It shall be underlined that due to lack of sufficient data the energy savings analysed are actually less than the effective savings of all the GreenLight Partners. Nevertheless the different subgroups of Partners are considered valid for the assessment.
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in case the energy savings justify such investments and the lighting quality is maintained or improved.
3
A list of the GreenLight National Contact Points, and all further information on the GreenLight Programme and participation are available on the official GreenLight Programme website (http://www.eu-GreenLight.org). 4
An interim evaluation of the results was given in the Five Year Report of the European GreenLight Programme [BER2005].
5
The relative savings are expressed as a percentual value of the total energy savings (achieved by the end of 2008) divided by the energy consumption before implementing the energy saving measures. Due to compass constraints this is not discussed in this paper.
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3. Expansion of the GreenLight Programme 3.1 Composition of Partners The number of GreenLight Partners was constantly increasing through the years, from around 80 in 2002 through 267 in 2005, reaching 519 by the end of 2008. This is about twice as much as at the end of 2005 [BER2005]. Figure 0.1 depicts the number of Number of Partners per country in 2008 Partners in the IT 116 different countries at BE 68 the end of 2008. FR 49 There are Partners in DE 43 the GreenLight ProES 35 AT 25 gramme from the PT 24 European Member RO 19 States, Norway and NL 16 Switzerland. Several LV 14 multinational comCZ 12 panies; Citigroup, SL 13 LT 12 Johnson & Johnson, NO 12 McDonald's Europe GR 10 and IKEA also joined SE 10 the Partners’ network PL 8 (they are denoted BG 7 under the category SK 6 CH 5 “M”, as multinational). DK 4 IE 4 M4 UK 2 FI 1
number of Partners
Figure 0.1. Total number of GreenLight Partners per country in 2008 6
Partners from the New Member States started to adhere to the GreenLight Programme only starting from 20067, when "New GreenLight"8 was launched. New GreenLight was a project co-ordinated by the Czech National Contact Point, with the scope of extending the GreenLight Programme to the New Member States. It was running for two years [NGL2009]. By the end of 2008, 90 new GreenLight Partners joined the GreenLight Programme, with a total energy saving of 59.5 GWh/year. In fact, 24 organisations whose applications were received under New GreenLight were accepted as GreenLight Partners in 2009. This makes the total number of Partners joining the GreenLight Programme under New GreenLight 114, with a total saving of 68 GWh/year9. 3.2 Energy savings Considering all the energy savings reported by the end of 2008, the total savings of GreenLight 10 Partners amount to 241 GWh/year . This is more than twice as much as the savings reported by 2005 [BER2005]. As not only the savings but also the number of Partners doubled with respect to 2005,
6
Bulgaria (2007), Cyprus (2004), Czech Republic (2004), Estonia (2004), Hungary (2004), Latvia (2004), Lithuania (2004), Malta (2004), Poland (2004), Slovakia (2004), Slovenia (2004), Romania (2007). 7
Except for the first Slovenian Partner, who adhered to the GreenLight Programme in 2003.
8
A project supported by the Intelligent Energy Europe Programme. For more information: http://ieea.erba.hu/ieea/page/Page.jsp?op=project_detail&prid=1644. A brochure with case studies is available on the GreenLight website (http://www.eu-greenlight.org/pdf/1_GreenLight_D4_CentralEurope.pdf. 9
This value may differ from previously published total savings, due to corrections and updates on savings reported to the Joint Research Centre by the Partner organisations. 10
This was reported by 350 Partners. For the remaining 169 Partners there is no adequate data available on the energy savings.
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considering the reported energy savings, it can be concluded that the average saving per Partner remained constant over time. The energy saving of 241 GWh/year generated a running cost saving of about 24 million EUR. 76% of the GreenLight Partners implemented lighting retrofits in buildings, on a total surface area of 3.5 2 million m . The remaining Partners’ projects were street lighting upgrades. 81% of the savings was achieved indoor. This share was approximately the same between indoor and outdoor savings by 2005 as well [BER2005]. Savings per country Figure 0.2 includes the total energy savings reported by GreenLight Partners in the participating countries, for the period from 2000 until 2008. The bars in green represent the savings achieved in each country by the end of 2008 (expressed in GWh/year). The orange bars show the share of energy savings in the particular country in comparison with the total GreenLight Programme savings (241 GWh/year).
Total savings per country IT DE RO
9.1
FR
5.2
BG
4.4
SL
4.0
ES
2.88
BE
2.8
PT
2.7
PL
2.6
CZ
2.5
CH AT NO LV DK LT
15.1
6.3
NL
21.9 15.5
6.4
M
GR
25.4
10.5
72.6
30.1
12.5 10.6 9.6
6.9 6.6 6.6 6.4
6.0 5.9
2.5 5.1 2.1 3.1 1.3 2.8 1.1 2.6 1.1 2.5 1.0 2.4 1.0
GWh/year % of savings
Figure 0.2. Energy savings of all GreenLight Partners per country, by the end of 2008 Countries with total savings below 1 GWh/year are not shown on the above figure. Italy achieved not only the highest number of Partners but also the highest savings as within one country. Italian Partners saved 73 GWh/ year by the end of 2008 giving 30% of all the energy savings achieved within the GreenLight Programme. More than 70% of the total savings was generated by two retail chain companies: the Italian Coop contributed with almost 30.5 GWh/year to the Italian total savings, while Carrefour Italia reported savings of 21.5 GWh/year. A significant share of savings was reported by two banks: UniCredit SpA and Intesa Sanpaolo, saving 4.8 and 4.5 GWh/year respectively. It shall be considered that there is no adequate data available on savings for more than 50% of the Italian Partners, the majority of them being municipalities, who mostly implemented street lighting projects. Germany is the country with the second highest total savings: 25.4 GWh/year. The city of Hamburg had a major contribution to this: between 2000 and 2007 about 450 public buildings were upgraded resulting in a total energy saving of about 10.3 GWh/year. To compare, this is approximately as much as the total Bulgarian energy savings. Data on the energy savings is not available for only five Partners (12% of all the German Partners). 20
Romania is an outstanding example of how a relatively small number of Partners can achieve significant savings and also, that there is a big potential for lighting savings in the New Member States. To translate this statement into numbers: 19 Romanian Partners joined GreenLight, starting from 2006, and they achieved a saving of 21.9 GWh which is the third highest saving per country in the GreenLight Programme. Romania is a role model – just like all the New Member States - also from the point of view that savings data is available for all the Partners in the country. The highest savings, namely 5.1 GWh/year were reported by Metrorex s.a., who is operating the subway in Bucharest, the capital city. Four other Romanian Partners saved 7.5 GWh/year through public building retrofits, followed by six further Partners saving 7.5 GWh/year too through street lighting projects. Considering the high number of Partners in Austria and Belgium, these countries’ total savings are not high. This is due to the fact that there is no data available for about 50% of the Partners in both cases. Savings per category Figure 0.3 depicts the distribution of savings reached by 2008 across the different categories, in which the Partners are active. R OS P C HR S PT A E U/T HP CP O
Retail: super markets Street Lighting (open space) Production City: Public Buildings Hotels/Restaurants Services: bank / insurance / etc. Public Transport: railway / metro stations Airports Educational Buildings: schools / universities Utilities/ Telecommunications Hospitals Car Parks Other
Total savings per category R
74.2
30.8
OS
18.9
P
13.0
C
12.9
HR
7.7
S
6.4 6.71 2.78 5.2 2.2 5.2 2.2 5.0 2.1 2.2 0.9 0.4 0.1 0.0 0.0
PT A E U/T HP CP O 0
10
45.6
31.3 31.2
18.5
15.5
GWh/year % of savings
20
30
40
50
60
70
80
Figure 0.3. Energy savings of all GreenLight Partners per category, by the end of 2008 The highest total savings – 31% of the total GreenLight Programme savings - were achieved in Retail11. The highest savings per Partner were also reported in this category (see Figure 0.4). This is thanks to some big retailers, such as Carrefour Italia, Coop in Italy, or Distribution Casino France, who reported savings between 10-31 GWh/year each. The three of them saved altogether about 62 11 Some examples of Partners and their savings in Retail were collected in a GreenLight brochure in 2002, available at: http://www.eu-greenlight.org/pdf/2002_GreenLight_retail_sector.pdf
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GWh/year, which represents 83% of the category's total. Not considering their contribution in the calculation, the average saving per Partner would be 467 MWh/year. This figure seems to be reliable for cross-comparisons, especially if we compare it to the corrected saving of Public Buildings per Partner which is 334 MWh/year (see below). In the shops lights are usually on for the entire period of the opening hours which are generally longer than the working hours, so that consumers can do their shopping before or after work. Plus, high lighting levels (up to 1,000 lux) are also required for a good product visibility. Therefore, it can be assumed that stores use more energy for lighting hence they save more in absolute figures. The second highest total savings were reported by Partners who modernized the public lighting system, giving close to 20% of the total GreenLight Programme savings. There are small municipalities and big cities among the Partners as well, with annual energy savings ranging from 8 MWh to 5 GWh. Most of the GreenLight Partners implemented street lighting projects (see Figure 0.4). Hence, the total savings in Street Lighting are prone to show a high value, even if there is no adequate data available for 44% of the Partners in Street Lighting. The average savings per Partner equal 660 MWh/year, which is around the GreenLight Programme average. The third highest savings, almost 15% of the total GreenLight Programme savings were achieved in Production. The number of companies active in this category is also the third greatest regarding the whole GreenLight Programme. The number of Partners who refurbished public buildings is higher than that of producers, but their total savings are not higher. It shall be added that data on the savings is available for more Partners in Production (60) than in Public Buildings (50). Projects in the category Public Buildings did not result in very high average savings per Partner. However, this number is not reflecting well the average savings per Partner: the city of Hamburg alone saved more than 10 GWh/year by the end of 2008, followed by the city of Zürich (4.9 GWh/year). Not considering their savings in the calculation, one Partner's average savings equal 334 MWh/year. Comparing this with the average saving of a Partner in the category Utilities/Telecommunications, where most of the upgrades were focused on the modernization of office buildings, it may be assumed that this number (334 MWh/year ) appears to be a more reliable source for cross-comparison of average savings per Partner.
Savings per Partner per category
10 000
1 855
1 304
1 118
1 000
881
660 123
100
49
624
521 99
388
4
356 148
74
33
10
374
47
118 43
22
13
6
6
10
3
1 R
A
PT
HR
OS
MWh/year R Retail: super m arkets A Airports Public Transport: PT railway / metro stations HR Hotels/Restaurants
OS C P S HP
C
P
S
HP
U/T
E
CP
O
number of Partners/category
Street Lighting (open s pace) City: Public Buildings Production Services: bank/insurance/etc. Hospitals
U/T Utilities/Telecomm unications Educational Buildings : E schools /universities CP Car Parks O Other
Figure 0.4. Average energy savings for one Partner per category Values are shown on a logarithmic scale to better visualize the number of Partners per category.
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As for Airports, the average savings per Partner are 1.3 GWh/year, the second highest. Airports are usually big complexes that have an extended surface area which needs to be illuminated, often also during night, as opposed to e.g. offices. So their absolute savings were expected to be high. The total savings are not outstanding, due to the fact that there are only a few Airports among the Partners. The savings per Partner in Public Transport equal 1.3 MWh/year. This high value can be explained by two factors. Like Airports, companies in Public Transport have generally a big surface area which needs to be illuminated. However, this is different in the sense that an airport is rather one big conglomerate while for example an underground line consists of a number of smaller stations. Still, if added up, this results in a high surface area. Another factor is that lighting is often needed during night as well, or in the case of an underground metro station also during the whole day. Showing some similarities, it is not surprising that Partners from Public Transport closely follow Partners from Airports as for annual savings per Partner. The total savings in Public Transport are low because of the small number of Partners in this category. The average savings per Partner of 881 MWh/year show a high value in the category Hotels/Restaurants. Partners with high savings cause a deviation in this value: Holland Casino Breda saved 9.5 GWh/year, while McDonald's Europe saved more than 6 GWh/year. Excluding these two Partners’ savings from the calculation, the resulting average saving per Partner is only 152 MWh/year.
Changes in technology The lighting technologies used in the GreenLight Partner projects have undergone a slow transition over the last eight years, from less efficient incandescent lamps, magnetically ballasted fluorescent lamps, and mercury vapour lamps to more efficient electronic fluorescent lamps and compact fluorescent lamps. Notably in regard to fluorescent lamps, the reduction in the size of the lamp has reduced the amount of energy needed to provide the same quantity of lighting. The use of electronically induced ballasts to charge the fluorescent lamps instead of magnetically induced ballasts, has not only reduced the amount of energy consumed per fixture, the electronic technology has improved the quality of the lighting. Not all retrofit projects entailed the replacement of lamps and fixtures. In some cases, lighting control was implemented to turn lights on and off with a schedule, with some type of occupancy linking technology (e.g., motion sensors), or by using photo sensors to dim lights in response to ambient daylight. Figure 0.1 below shows the installations of the respective categories of lights over the 2000 to 2008 time period. Partners were required to report only about lighting types and quantities pertinent to their retrofit projects so it is not possible to ascertain the actual mix of lamp types in the entire facility or facilities managed by each Partner; though it is reasonable to assume that the energy savings roughly mirror the most significant sources of energy consumption.
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Energy Savings by Category 2000 to 2008
35 30
GWh Saved
25 20 15 10 5 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 Incandescent Lamps
Fluorescent Lamps
Other Lamps
Total Lighting Controls Other Lamps Fluorescent Lamps Incandescent Lamps
Lighting Controls
Total
Figure 0.1. Energy savings by lighting retrofit for the period 2000 to 2008.
3.3 Changes in lamps Table 0.1 below summarises the energy saving and Partner percentages per lamp type retrofit. The energy savings percentages sum to 100% of the total available energy savings reported by the Partners performing the lighting retrofits. However, some Partners performed multiple types of retrofits so the number of Partners will total more than the number of Partners who reported technology changes. Table 0.1. Lamp changes summary Retrofit category Incandescent to incandescent* Incandescent to fluorescent conversion Incandescent to other conversion Fluorescent to fluorescent Other to fluorescent conversion Other lamps to other lamps Lighting Controls Total
Partners 13 33 7 109 33 58 81
Energy savings, % category 0,8% 4,0% 7,5% 21,6% 28,3% 20,2% 17,6% 100,0%
Energy savings kWh, category 1 124 140 5 620 690 10 538 800 30 351 730 39 766 390 28 384 490 24 731 040 140 517 280
* The incandescent to incandescent type of lamp retrofit is normally not allowed within the GreenLight Programme unless there is a reduction in the number of fixtures or a reduction in lamp power.
Fluorescent to fluorescent retrofits
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The largest change in fluorescent to fluorescent retrofits has been the conversion of T8 lamps to T5 lamps, both in terms of Partners implementing the retrofit and in terms of the energy savings (approximately 10% of the total reported lamp energy savings within the GreenLight Programme). Retrofits from T12 lamps occurred earlier in the GreenLight Programme but the frequency of this retrofit has decreased considerably because most Partners have changed to T8 and T5 lamps. The T8 to T8 retrofits appear to be mostly composed of two components of savings (yielding roughly 15 – 18% energy savings per fixture); (1) changes from halophosphate lamps to triphosphate lamps and (2) from magnetic to electronic ballasts. However, some T8 to T8 lamp retrofits appear to involve delamping, though it is difficult to quantify these delamping energy savings because fixture lighting coverage area is not a reportable item and lighting changes sometimes include multiple lamp types. There were a variety of lamp changes within the “other” category, such as CFL to CFL, T5 to CFL, and T5 to T5 lamp changes, but these changes appear to be motivated by specific applications of lighting required at that Partner’s facility and are not reflective of a trend. Not reflected in this data is a trend in the conversion of lamps from incandescent lamps and other types of lamps to the use of compact fluorescent lamps that are similar in application as the linear T5 lamps. There is the potential of a larger adoption of single pin fluorescents in place of the typical linear double pin fluorescent lamps because this allows greater flexibility in the placement of the lamp within the fixture. Table 0.2 below shows the percent change values by lamp change category. Table 0.2. Fluorescent to fluorescent lighting changes Lamp change category T8 to T8 T8 to T5 T8 to CFL T12 to T8 T12 to T5 T12 to CFL Other
Partners, % category 19,0% 40,5% 17,4% 5,8% 4,1% 3,3% 9,9%
Energy savings, % category 11,4% 44,9% 8,5% 0,5% 2,5% 8,1% 24,0%
Energy savings kWh, category 3 464 315 13 649 954 2 596 655 145 419 770 592 2 468 142 7 307 106
Other lamps to fluorescent retrofits The largest change in other lamps to fluorescent retrofits has been the conversion of mercury vapour lamps to T5 fluorescent lamps, both in terms of Partners implementing the retrofit and in terms of the energy savings. This category is the largest category of lamp conversion energy savings of total energy savings within the GreenLight Programme, resulting in 13% of the total energy savings. Although conversions of other lamps to T8 fluorescent lamps was accomplished by several Partners, these conversions involved relatively low levels of energy savings so these were not significant categories of retrofit. The lighting industry is migrating to T5 fluorescent lamps so future energy saving retrofit projects will likely concentrate on the use of T5 lamps. Table 0.3 shows the percent change values by category. Table 0.3. Other lamps to fluorescent lighting changes Lamp change category Mercury vapour to T5 Mercury vapour to T8 Mercury vapour to CFL Metal halide to T8 Metal halide to CFL Metal halide to T5
Partners, % category 18,6% 14,0% 11,6% 23,3% 25,6% 7,0%
Energy savings, % category 46,8% 3,7% 3,8% 8,8% 34,9% 2,1%
Energy savings kWh, category 18 600 975 1 460 786 1 509 561 3 509 034 13 857 545 817 645
Other lamps to other lamps retrofits For other lamps to other lamps retrofits, 58 Partners reported this type of lamp conversion. This change accounted for approximately 20.2% of the total reported technology energy savings in the
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GreenLight Programme during the 2000 – 2008 time period, the second largest group after fluorescent to fluorescent retrofits. There are 7 categories of other lamps to other lamps lighting changes: mercury vapour to metal halide, mercury vapour to HP sodium, HP sodium to HP sodium, neon to LED, metal halide to metal halide, mercury vapour to mercury vapour, and other lamp changes. The most significant change in other lamps to other lamps retrofits has been the conversion of mercury vapour lamps to HP sodium lamps, both in terms of Partners implementing the retrofit (59.3% of all the Partners retrofitting other lamps to other lamps) and in terms of the energy savings (17.5 GWh/year). The majority of these Partners were public sector entities upgrading their street lighting. These street lighting retrofits provide a significant amount of energy savings and account for the reason this category yielded 61.7% of the other lamps to other lamps energy savings, and approximately 12.5% of the total GreenLight Programme energy savings. Although the conversions of mercury vapour to metal halide lamps involved relatively few Partners (12.3% thus 8 Partners), some of them (active in production) achieved significant savings. This is the reason for this lamp change category yielding the second highest savings within the other lamps to other lamps retrofits (22.1% corresponding to 6.3 GWh/year). Energy savings in the other lamp change categories were not significant. 3.4 Ballast changes GreenLight Programme Partners reported ballast changes for fluorescent lamps and for other lamps such as mercury vapour, metal halide, and HP sodium. Although Partners reported ballast types for lamp retrofits of mercury vapour, metal halide, and HP sodium lamps, these ballast replacements are magnetic to magnetic when a high intensity discharge (“HID”) type lamp is retained with the retrofitted fixture. While there is interest in obtaining additional energy savings from the use of electronic ballasts in HID fixtures, magnetic ballasts in these fixtures still offer better cold and hot weather life and performance. Therefore the focus in this section is on the ballast upgrades of fluorescent lighting, and especially on changes from magnetic to electronic ballasts. In those cases where the Partner continued to use magnetic ballasts the energy savings were either generated by lighting controls or de-lamping of existing fixtures. If the Partner already was using electronic ballasts then the savings were obtained by implementing lighting controls and/or upgrading to better electronically ballasted lighting (such as converting T8 lamps to T5 lamps). Table 0.4 below shows the percent change values by category. Table 0.4. Ballast changes Ballast change category Magnetic to electronic Magnetic to magnetic Electronic to electronic
Partners, % category 92,3% 3,1% 4,6%
Energy savings, % category 75,6% 23,5% 0,9%
Lighting Control % category 31,6% 2,5% 0,8%
3.5 Lighting controls Localized manual switching is providing individuals in open office configurations a local (task or work based) light switch instead of controlling the light from a single area switch; allowing each individual the opportunity to use only the lighting needed for his/her work area. Time scheduling provides an automated clock based schedule of the lighting to ensure that the lighting is turned off in work areas that are scheduled to be unoccupied. Occupancy linking allows the lighting to be turned on and off in conjunction with the occupancy of the space via some type of presence sensing control. Daylight responsive controls dim the artificial lighting when the ambient daylight reaches sufficient intensity levels.Table 0.5, Lighting controls, below, shows the percent change values by category.
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Table 0.5. Lighting controls Lighting control category Localised manual switch Time scheduling Occupancy linking Daylight responsive
Partners, % category 40,8% 23,8% 15,4% 20,0%
Energy savings, % category 45,0% 21,0% 9,6% 24,4%
Energy savings kWh, category 11 136 515 5 196 481 2 384 862 6 049 276
The largest amount of energy savings from lighting controls retrofits has come from installing daylight responsive controls, even though this category of savings was implemented only 20.9% of the time. The occupant density in most work spaces is highest during the day so this provides a significant opportunity to reduce energy consumption without reducing work productivity. Time scheduling was also an important lighting controls measure providing significantly higher saving by category than localized manual switching and occupancy linking. Time scheduling has the additional benefit of being relatively simple to implement and operate. It is important to have regular energy conservation training that emphasizes turning off equipment and lights when they are not needed; however, time scheduling supplements those efforts by ensuring that the lights are turned off when not needed. Summary and outlook The energy savings reported by the Partners participating in the GreenLight Programme provide a good snapshot of the energy savings that are available to those willing to upgrade their lighting systems. Partners concerned about conserving energy have many opportunities to improve the lighting in their facilities and in turn reduce their environmental footprint. Organisations interested in saving money can invest in the new lighting technologies to obtain new and better lighting systems and lower their energy bills. The basic lighting energy savings strategies are not complex. This report shows that the main strategies of converting mercury vapour lamps to more efficient lamp types, converting older fluorescent lamps and ballasts to T5 lamps and electronic ballasts, implementing daylighting controls where possible, and installing timing controls to shut off lights when the building is unoccupied, are appropriated for most Partners and tend to generate the most energy savings. Advances in lighting technologies appear to be continuing as the lighting industry introduces better and more versatile compact fluorescent fixtures. The service life of fluorescent lamps has been increased to nearly match the life of high pressure gas lamps. The efficiency of fluorescent lamps continues to improve and may eventually be a cost competitive choice along side high pressure sodium lamps. High pressure gas discharge lamps can be installed with electronic ballasts to improve the start up of the lamp, improve the quality of the light, and lengthen lamp life. In the short and long term, LED lamps show significant potential for increasing lighting efficiency and also lighting effectiveness. Although, currently available LED lamps are less efficient than compact fluorescents, new developments indicate that efficiency of LED lamps will improve quickly. LEDs have a long service life (approximately 50.000 hours), have good colour rendering, can be dimmed, and allow for a large variety of fixture configurations. Their small size lends itself to more localised applications improving effectiveness by putting light where it is most useful. The high cost of LED lamps is still a limiting factor but the cost per lumen is expected to continue to drop.
GreenLight Partners’ motivation and experience The Joint Research Centre conducted a survey between November 2008 and June 2009 among the GreenLight Partners. The main goal of this survey was to elicit Partners’ attitudes and experiences with the GreenLight Programme by 2008/2009. By use of a Questionnaire, Partners were asked to answer two issues: • Motivation, barriers and commitment in the planning phase, i.e. before implementing the energy saving measures and applying to join the GreenLight Programme. • Evaluation of benefits, success of the finished or ongoing project and the whole GreenLight Programme.
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Data input The total number of Partners participating in the GreenLight Programme within the survey period amounted to 519 by the end of 2008, but increased to 560 by the end of the survey period. Some Partners could not be reached, or could not respond within the scheduled time period for data collection. At the end of the data collection period 104 responses were available for the survey evaluation. Some of them were not complete, i.e. lacked responses to parts of the Questionnaire. Table 0.1 shows the summary of the information provided or missing in the responses finally evaluated. Table 0.1. General description of the data material Data description Partners (by the end of survey period) Total responses Complete responses Non-responses
Total 560 104 95 456
% 100,0 18,6 17,0 81,4
The sample of Partners represents roughly one fifth of the addressed Partners (104 from 560 12 Partners ). The distribution of countries in the sample is similar to the distribution of the entire population. The distribution of project types is also similar to that of the entire population, except for small deviations in some categories (Public Buildings and Hotels/Restaurants are weaker, while Production is stronger represented in the survey). To this extent there is the possibility of minor variances from Partner comparisons presented in this report. But in the response cases where the analysis strongly shows a clear trend or outcome, the resulting conclusions are significant and valid. Results On the basis of the responses to the Questionnaire, the results can be summarised as follows. Planning phase Most of the Partners had different motivations for joining the GreenLight Programme. The results show that energy savings and cost reduction are the most important motivations: 88% of the respondents indicated this factor as a higher motivation for joining the GreenLight Programme. This is followed by 13 improvement of environmental image (67% of the responses), lighting quality (66% the responses) and in-house environmental awareness14 (60% the responses). However, executing a general renovation15 which includes a renovation of the lighting system was considered to be a lower motivation for participation in the GreenLight Programme. A small part of the responses, i.e. approx. 6%, provided additional items of motivation. The compilation of those responses showed that having an additional tool for improved marketing, building networks with important stakeholders (e.g. National Contact Points, other Partners) or raising safety (Street Lighting) were important motivations. Technical, management, and end-use problems were not deemed to be significant barriers to implement energy efficiency measures. However, the estimation of costs and benefits was a problem for almost half of the respondents (46 from 94 responses, i.e. 44%). Several of these responses were delivered by “big” Partners, i.e. private companies with energy savings exceeding 500 MWh per year (7 responses) and providers for street lighting (4 responses from Partners who saved more than 1.4 GWh per year). The comments revealed that many Partners were not certain about their cost-benefit analysis or found it to be too time and resource consuming. There was a strong correlation between Partners who perceived cost estimation barriers and Partners who had multiple facilities and/or lacked a submetering system. A factor not explicitly included in the Questionnaire, financing the project, may actually be behind some of the responses regarding barriers. Six from the 46 Partners indicated that financing the project per se was the main barrier instead of the estimation of costs and benefits. 12
as at the end of the survey period.
13
Environmental image in this survey meant the image of the organisation for the outside world (business partners, customers, etc.) regarding the organisation’s commitment and concern towards environmental issues. 14
In-house awareness in this survey meant to raise the environmental awareness of the organisation’s personnel.
15
General renovation in this survey meant the lighting project was done as a part of a larger project to renovate the facility.
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Evaluation after project implementation After implementation of the project more than 75% of the responding Partners deemed project benefits (such as energy savings, cost reductions, lighting quality, in-house awareness, environmental image, and other) to be the same or higher than initially expected. Higher benefits than initially expected were stated with regard to in-house environmental awareness (44 from 92 responses) and environmental image (47 from 88 responses). This may suggest that “soft” criteria such as environmental awareness and image may be underestimated at the beginning of the planning process. Even if Partners initially focus their decision making activities for lighting efficiency on quantitative economic targets (savings), they may eventually recognise that the non-economic benefits of the project have a significant positive impact on their organisation; and also the customers and users of their products or services. More than 81% of the responding Partners were satisfied with project outcomes, such as implementation costs, technical improvements, acceptance from personnel, users and customers. In the end, Partners evaluated the GreenLight Programme as a whole positively: 88% of the respondents declared that they are satisfied (51%) or very satisfied (37%) with the GreenLight Programme, while 14% of the respondents stated that they would have not introduced energy efficiency measures without the GreenLight Programme. Partners expressed a clear need for further promotion of the GreenLight Programme towards the public and within the Partners’ network. Outlook There is a need for further research in the GreenLight Programme Partners’ motivations and barriers. Evidence gained through this survey suggests some trends that should be further investigated in the future: • Regarding motivation for Partners to participate in the GreenLight Programme, environmental image seems to be an important co-driver whenever the Partner has motivations to pursue energy savings, cost reductions, improvements of lighting quality, or raising in-house awareness. • Participating in the GreenLight Programme does not seem to be related to doing a lighting retrofit as part of a general renovation. The motivations of the larger general renovation project may override the motivations of the lighting retrofit part of the project. • Estimation of costs and benefits may be a problem for some Partners. They were uncertain about their cost-benefit analysis, or found it to be too time and resource consuming. • Whereas the estimation of costs and benefits and the persuasion of senior management may impede the development of an energy efficient lighting project, financial and/or budget limitations are real barriers. • Frequently, in-house environmental awareness and the Partner’s environmental image seem to yield a higher benefit than initially expected. Thus, “soft” criteria such as environmental awareness and environmental image may be underestimated at the beginning of the planning process. • Improvement of lighting quality may be a more important benefit for open spaces than for indoor applications. • Partners, who have recently joined, will probably need a period of time in order to accept the successful outcomes of their project, and then internalize the reasoning for engaging in similar energy savings projects in the future.
Conclusion There were some challenges in evaluating the GreenLight Programme since the programme’s start in 2000. The most significant barrier in the evaluation of the GreenLight Programme is how to make the reporting process more efficient so that the quality of the data reported remains high, the programme provides a good view of technology changes in Europe, and Partners are adequately encouraged to continue implementing energy efficient lighting within the programme. Based on the analysis of the expansion of the GreenLight Programme in this report and the responses of Partners to the survey conducted, recommendations for a more widespread and smoother running GreenLight Programme may be summarised as follows:
29
•
More publicity. Possible means: stronger public communication through the internet, television, conferences, papers, reporting. Newsletters, promotional materials, technical support and advice to Partners, best practice seminars. Participation of the National Contact Points could be of crucial importance.
•
Application and reporting should be possible online. This would ensure a smoother expansion of the GreenLight Programme by speeding up the application process on both ends. On the one hand, online forms make it possible to require all the necessary information from the applicant before being able to submit the application. On the other hand, it eases the administration: if forms are filled in properly, there is no need to contact the applicants for clarifications or additional information.
•
New Partners should be accepted only if data on the achieved energy savings is submitted together with the application. This would eliminate the problem of missing data which has two benefits: Partners would not need to be contacted regarding data on energy savings and an evaluation of the savings could be done easier based on a larger dataset. In addition, an online reporting form gives the possibility of controlling the data provided in real time, i.e. while the applicant is filling in the reporting form. Any inconsistencies can be pointed out, moreover, clearing existing incongruities can be made a precondition for submitting the reporting form.
•
Partners should be required to upgrade their lighting system through reasonable time periods keeping up with lighting technology improvements otherwise they could drop out of the GreenLight Programme. Many Partners implemented one lighting refurbishment and joined the GreenLight Programme. After that particular refurbishment only a few Partners (e.g. Athens International Airport) planned or executed further lighting efficiency improvements in the same facilities. The optimal method for determining the frequency of upgrades to the lighting system was not discussed in this report. This could be a subject of further research. It shall be noted that since the GreenLight Programme is a voluntary programme, expanding the obligations of Partners harbours the risk of non-compliance. However, this particular recommendation is aimed at encouraging Partners to continue investing in energy efficiency by adding a reasonable extra requirement. Public recognition under the aegis of the GreenLight Programme shall be offered to Partners who earn it.
References This paper is based on the report: The European Greenlight Programme 2000-2008 – Evaluation and outlook. The report is soon to be published and will also be available on the GreenLight official website: http://www.eu-GreenLight.org. Further references [BER2005] Bertoldi, P., Ciugudeanu, C.N. 2005. “Five Year Report of the European GreenLight Programme”. In: EC, DG JRC, Institute for Environment and Sustainability, Renewable Energies Unit, EUR 21648, Ispra. [EGL2009] www.eu-greenlight.org. Official website of the European GreenLight Programme. [NGL2009] New GreenLight. A project supported by the Intelligent Energy Europe Programme. http://ieea.erba.hu/ieea/page/Page.jsp?op=project_detail&prid=1644.
30
Reducing Energy Consumption and Peak Demand in Commercial Buildings Iris Sulyma and Ken Tiedemann BC Hydro, Vancouver, Canada
Abstract BC Hydro’s Power Smart Product Incentive Program (PIP) offers financial incentives to encourage business and institutional customers to install a wide variety of simple retrofit installations and save energy. The purpose of this paper is to provide a market and impact evaluation of the Product Incentive Program. The market evaluation examines end use electricity consumption by building type and the nature of program participation by building segment. The impact evaluation examines the program’s energy impacts, peak impacts and cost effectiveness.
Introduction BC Hydro’s Power Smart Product Incentive Program (PIP) began in November 2003. PIP offers financial incentives to encourage business and institutional customers to install a wide variety of simple retrofit installations and save energy. A wide variety of products are eligible for PIP, although the bulk of savings to date have come from energy efficient lighting products. The program is administered primarily through an online application site over the Internet, which simplifies application procedures and keeps program administrative costs low. The goals of PIP include the following. (1) Generate energy savings for BC Hydro by replacing inefficient technologies with more efficient technologies. (2) Increase energy efficiency awareness by actively communicating energy efficient product options. (3) Educate customers on the benefits of energy efficient products. (4) Contribute to market transformation for specific technologies. (5) Better meet the needs of underserved small and medium business customers. (6) Increase business customer satisfaction. This purpose of this paper is to provide a market and impact evaluation of the Product Incentive Program. The market evaluation examines end use electricity consumption by building type and the nature of program participation by building segment. The impact evaluation examines the program’s energy impacts, peak impacts and cost effectiveness.
Data and Method Data extracts containing information on all the PIP projects completed in fiscal year F2008 (April 1, 2007 through March 31, 2008) were obtained in February 2009. The extract contained a variety of information on existing PIP projects including program dates, application status, types and quantities of products installed, estimated energy savings, and incentives awarded. This database was analyzed to provide an overview of PIP program activity. Customer awareness, satisfaction, program experiences, and respondent free rider and spillover questions were summarized from a telephone survey of 150 program participants conducted in the spring of 2008. Participant respondents were recruited from a list of PIP applications for the relevant period. Gross and net energy savings were estimated for program activity completed in the period April 1, 2007 through March 31, 2008. Gross savings are the basic estimate of program savings and are usually based on an engineering study and/or technical calculations. Gross savings generally do not account for factors external to the program that could impact energy savings and may therefore include energy savings that are not attributable to the program. In contrast, net savings are estimated by adjusting the initial gross savings estimates by the expected influences of non-Program related factors including free-ridership, spillover, and naturally occurring conservation.
31
Gross savings estimates for PIP are calculated automatically when the customer enters the project information into the online application form, with these estimates relying on deemed savings algorithms for each technology type. Gross evaluated electricity savings were estimated using the following algorithm, where W pre and W post are the wattages of the original and replacement products, hours refers to hour of use for the relevant space type, area refers to the area of the relevant space type and the summation is over areas: (1)
Gross kWhsavings = Sum (W pre – W post) * hours of usearea /1000.
Since the program applications provided these calculations with assumed hours of use, the major calculation here was to correct the assumed hours of use by space-weighted actual hours of use based on metering data. Gross peak demand was estimated by using the ratio of average kWh to peak kWh from engineering analysis. Net electricity savings were estimated using the following algorithm, W pre and W post are the wattages of the original and replacement products, hours refers to hours of use for the relevant space type, area refers to the area of the relevant space type, and the summation is over areas: (2)
Net kWhsavings = Sum (W pre – W post) * hours of usearea /1000*(1 – free rider rate + spillover rate).
Net peak demand was estimated by using the ratio of average kWh to peak kWh from previous engineering studies. We compared the cost effectiveness of the main technologies installed under PIP using the cost of conserved energy, where the estimated installed cost for each technology came from data collected for the pre-program baseline. The cost of conserved energy is the ratio of the present value of the stream of costs to the present value of energy saved. If all costs occur at time zero, then the cost of conserved energy (CCE) can be written as follow where cost refers to the full installed cost of the product, gross kWh refers to savings for the technology, d is the discount rate of 0.06, and n is the useful life of the product, which we assume is ten years: (3)
CCE = (cost/KWhsaving)*(d/ (1 – (1 + d)-n).
End Use Consumption Table 1 summarizes end use electricity consumption for commercial and institutional buildings. This data is based on site visit data used to inform DOE 2.1 modeling of 316 commercial and institutional buildings. The information provided annual end-use consumption per square foot, based on normal weather and full occupancy for thirteen building segments (grocery, hotel/motel, health care, low rise office, high rise office, library, recreation centre, retail, restaurant, elementary school, secondary school, wholesale and miscellaneous) for ten end-uses (space cooling, space heating, interior lighting, equipment, HVAC auxiliaries, refrigeration, exterior lighting, elevators, domestic hot water and cooking). Three features of this data are worth noting. First, average total consumption per square foot per year varies substantially across building segments, from a low of 10.2 kWh per square foot per year for elementary schools to a high of 74.0 kWh per square foot per year for grocery stores. Second, for most building segments, interior lighting is the most important end use with refrigeration for grocery stores and recreation centres, domestic hot water for hotels/motels, and equipment for restaurants and miscellaneous establishments among the biggest end uses. Third, given the relative sizes of the various end use loads, the best opportunities for future energy savings include space cooling, space heating, interior lighting, equipment and HVAC auxiliaries such as fans and pumps.
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Table 1. End-use Electricity Consumption (kWh/ft2/year)
Facility type
Cool
Heat
Int light
Equip
HVAC aux
Refrig
Ext light
Elev
DHW
Cook
Total
Grocery
2.4
1.9
14.4
4.6
5.6
28.0
3.0
0.3
4.2
9.6
74.0
Hotel/motel
1.1
4.7
6.1
2.7
2.7
1.1
0.8
0.8
10.1
1.1
31.2
Health care
0.5
4.3
5.7
1.9
3.3
0.5
0.4
0.5
1.6
0.7
19.4
High rise off
2.9
3.3
8.0
2.8
4.4
0.1
0.7
0.6
0.8
0.3
23.9
Low rise off
1.9
2.7
7.1
2.5
3.5
0.5
0.8
0.8
0.4
0.4
20.6
Library
1.5
3.7
8.2
1.8
3.1
0.1
0.9
0.8
0.5
0.2
22.2
Rec centre
1.4
2.6
6.9
2.8
6.8
9.2
0.6
0.5
1.0
0.6
32.4
Retail
1.8
2.3
9.9
2.3
3.5
0.1
3.1
0.6
0.9
0.5
25.0
Restaurant
3.5
4.0
9.7
17.8
9.2
3.2
4.3
0.2
3.6
10.0
65.5
Elem school
0.2
2.8
3.5
0.5
1.8
0.1
0.3
0.2
0.2
0.6
10.2
Sec school
0.3
4.4
4.1
0.8
2.1
0.1
0.3
0.1
1.0
0.2
13.4
Wholesale
1.1
3.9
7.8
5.3
2.4
15.9
0.9
0.2
0.5
2.2
39.2
Miscellaneous
1.9
2.6
7.9
16.1
7.0
1.6
1.5
1.0
1.5
0.3
41.4
Customer Survey Customers were asked how they became aware of program awareness for PIP. The most important electrical distributor or contractor (37%), BC Representative (31%), BC Hydro website (19%) literature (14%).
PIP. Table 2 shows their main reported sources of sources of customer awareness of PIP were an Hydro Account Manager or Customer Care and BC Hydro bill inserts or other promotional
Table 2. Sources of Participant Awareness of PIP (%) Source
Share (%)
Electrical distributor or contractor
37
BC Hydro Account Manager or Customer Care Representative
31
BC Hydro website
19
BC Hydro bill inserts or other promotional literature
14
Consultants or other service firms
12
Colleagues
10
Trade publications
2
Don’t know/ refused
4
Customers were asked about the importance of various factors in their decision to participate in PIP. Table 3 provides participants’ responses to a series of questions on the importance of various factors on their decisions to participate in the Product Incentive Program. The response categories were as follows: (1) not at all important; (2) not very important; (3) neither important nor unimportant; (4) somewhat important; (5) very important; and (6) don’t know or not applicable. The most important
33
factors included reducing energy use to save money (top box score of 4 or 5 out of 5 of 89%) and reducing energy use to save the environment (top box score of 4 or 5 out of 5 of 89%). Table 3. Importance of Various Factors on PIP Participation Decision (%) 1
2
3
4
5
DK
Advice from a BC Hydro representative
10
8
17
26
29
9
Advice from contactor or distributor
5
9
18
127
37
5
Reducing energy use to save money
0
0
9
18
71
1
Expected incentive from the program
1
5
19
41
32
3
Reducing energy use to benefit environment
1
2
7
24
64
1
Customers were asked about their satisfaction with various components of PIP. Table 4 provides participants’ responses to a series of questions on their satisfaction with components of the Product Incentive Program. Once again, the response categories were as follows: (1) not at all satisfied; (2) not very satisfied; (3) neither satisfied nor dissatisfied; (4) somewhat satisfied; (5) very satisfied; and (6) don’t know or not applicable. Areas with high satisfaction levels included service provided by contractors, distributors and BC Hydro personnel. Areas with lower levels of satisfaction included direct mail information about PIP and the level of incentives offered. Table 4. Customer Satisfaction (%) 1
2
3
4
5
DK
Direct mail information about PIP
6
6
22
33
15
19
Information about PIP on website
1
2
13
41
31
13
Service provided by BC Hydro personnel
3
3
8
32
48
5
Service provided by your distributor
0
2
10
31
52
4
Service provided by your contractor
0
2
3
27
56
10
Level of incentives offered
3
5
23
40
28
1
Variety of products funded under the program
1
4
17
48
23
1
Usability of the online application
0
7
14
33
35
11
Application procedures to receive funding
1
5
16
35
40
3
Your overall experience with the program
1
2
10
42
45
0
Market Analysis The market analysis focused on two main considerations. First, what were the amounts and shares of the main products installed through PIP? Second, what were the main facility types and shares participating in PIP? Table 5 provides information on product installations and incentives paid by type of product. The total number of products installed under PIP for F2008 was 276,751. The product shares were: standard T8 lamps (5.1%); energy saving T8 lamps (60.0%); compact fluorescent lamps or CFL (17.2%); metal halide lamps (2.3%); halogen infrared lamps (0.9%); other lighting products (11.0%); and mechanical and other products (3.6%). It is worth noting that lighting products made up about 96% of all products installed under PIP while lighting products made up about 87% of incentives paid.
34
Table 5. PIP Product Installations by Type, F2008 Quantity
Incentives paid
Number
Share (%)
Dollars
Share (%)
Standard T8 inc ballasts
14,048
5.1
194,800
15.6
Energy saving T8 inc ballasts
165,979
60.0
533,018
42.7
CFL
47,675
17.2
135,136
10.8
Metal halide
6,263
2.3
81,728
6.5
Halogen infrared
2,393
0.9
2,471
0.2
Other lighting products
30,487
11.0
138,505
11.1
Mechanical and other
9,906
3.6
163,171
13.1
276,751
100.0
1,248,829
100.0
Total
Table 6 summarizes the distribution of PIP applications by facility type. The total number of applications under PIP for F2008 was 697. The applications shares were: large grocery (1.0%); hotel/motel (24.5%): health care (3.7%); office (20.5%); large retail (1.9%); restaurant (1.6%); elementary school (2.6%); secondary school (2.0%); wholesale/warehouses (1.0%); industrial (4.6%); miscellaneous (18.9%): and unknown (17.8%). It is worth noting that program activity is quite concentrated by building segment, as just two building segments (hotel/motel and offices) account for 45.0% of the applications.
Table 6. PIP Applications by Facility Type, F2008 Facility type
Number of applications
Share (%)
Large grocery
7
1.0
Hotel/motels
171
24.5
Health care
26
3.7
Office
143
20.5
Large retail
13
1.9
Restaurant
11
1.6
Elementary school
18
2.6
Secondary school
13
2.0
Wholesale/warehouses
7
1.0
Industrial
32
4.6
Miscellaneous
132
18.9
Unknown
124
17.8
Total
697
100.0
Energy and Peak Impacts Gross and net energy savings were estimated for program activity in the period April 1, 2007 through March 31, 2008, using the methods outlined above. The results are shown by technology group in Table 7, where FR stands for free rider rate and SO stands for spillover rate. Annualized net savings
35
were as follows: standard T8 (2.0 GWh); energy saver T8 (5.3 GWh); CFL (11.2 GWh); metal halide (1.6 GWh); halogen infrared (0.3 GWh); other lighting (2.6 GWh); and mechanical and other (1.9GWh). Table 7. Estimated Energy Impacts Technology
Gross savings
1 – FR + SO
Net savings
Standard T8
1.786
1.033
1.972
Energy Saver T8
4.524
1.105
5.344
CFL
10.011
1.045
11.183
Metal halide
1.449
1.019
1.578
Halogen infrared
0.332
0.796
0.283
Other lighting
2.358
1.019
2.569
Mechanical and other
1.874
0.989
1.853
Total
22.334
24.782
Table 8 summarizes evaluated energy savings and peak savings for the Product Incentive Program for F2008. Evaluated energy savings were 24.8 GWh compared to program reported energy savings of 27.5 GWh. Evaluated peak savings were 3.4 MW compared to program estimated based peak savings of 3.8 MW. Evaluated savings are about 90% of reported savings for the period covered by this study. The difference between reported and evaluated energy savings is due to two factors. First, the evaluated weighted average hours of use based on end use metering is lower than the hours of use used in the program algorithms which were used to generate program savings estimates. Second, the evaluated net realization rate (that is, the quantity one minus the free rider rate plus the spillover rate) is higher than that used in the program algorithms. Note that these two effects are offsetting in the sense that the first factor reduces estimated savings while the second factor increases estimated savings. Table 8. Program Energy Savings and Peak Savings Program Product Incentive Program
Period F2008
Energy (GWh)
Peak (MW)
Reported
Evaluated
Reported
Evaluated
27.5
24.8
3.8
3.4
Cost Effectiveness Table 9 summarizes cost effectiveness for sixteen main technologies installed under PIP. The cost of conserved energy estimates vary quite widely across product categories. For lighting products, the cost of conserved energy varies from $0.016 per kWh for energy saver T8 fluorescent tubes to $0.048 per kWh for pulse start metal halide lamps and for photocell lighting controls. For mechanical products, the cost of conserved energy varies from $0.014 per kWh for synchronous belts to $0.060 per kWh for adjustable speed drives Table 9. Cost-effectiveness of Selected Technologies Technology
Installed cost ($/unit)
Savings (kWh/year)
CCE ($/kWh)
Pulse start metal halide
104.90
296
0.048
Halogen infrared
18.50
58
0.044
Occupancy sensor lighting
75.00
443
0.023
36
Photocells
60.20
173
0.048
Energy saver T8
3.00
25
0.016
Energy saver T8 and ballast
42.70
239
0.024
High bay fluorescent
170.00
523
0.044
High wattage CFL
9.50
202
0.047
Standard wattage CFL
2.75
104
0.027
5,000.00
42,300
0.016
ASDs (per horse power)
400.00
900
0.060
Synchronous belts
14.80
140
0.014
Transformers (per kVA)
27.30
70
0.053
50,000.00
135,000
0.050
HVAC occupancy sensor
239.40
1,080
0.030
Carbon dioxide sensor
747.70
2,970
0.034
Switch plate timer
61.50
288
0.029
Pony pump motors
Harmonizers
Summary of Findings Overview. PIP has been successful in building a high level of product awareness and purchase behaviour for energy efficient lighting products in the commercial sector and institutional sector. The program has been gaining momentum, with increased customer applications for efficient lighting products and, to a lesser extent, for mechanical products leading to increased annual savings. End Use Consumption. DOE 2.1 models based on detailed on-site audits were used to examine end use consumption by building type. The analysis found that: (1) total consumption per square foot varies substantially across building segments, from a low of 10.2 kWh per square foot per year for elementary schools to a high of 74.0 kWh per square foot per year for large grocery stores; and (2) for most building segments, interior lighting is the most important end use with refrigeration for large grocery stores and recreation centres, domestic hot water for hotels/motels, and equipment for restaurants and miscellaneous establishments among the biggest end uses. Customer Survey. A detailed survey was conducted with 150 program participants, covering a range of program aspects. Customers were asked how they became aware of PIP, and the most important sources of customer awareness of PIP were an electrical distributor or contractor (37%), the BC Hydro Account Manager or Customer Care Representative (31%), BC Hydro website (19%) and BC Hydro bill inserts or other promotional literature (14%). Customers were asked about the importance of various factors in their decision to participate in PIP: the most important factors included reducing energy use to save money (top box score of 4 or 5 out of 89%) and reducing energy use to save the environment (top box score of 4 or 5 of 89%). Customers were asked about their satisfaction with various components of PIP: higher satisfaction levels areas included service provided by contractors, distributors and BC Hydro personnel, while lower satisfaction levels included direct mail information about PIP and the level of incentives offered. Market Analysis. To understand market impacts, we examined the distribution of applications by product type and by facility type. Total product installations under PIP for F2008 were 276,751. The product shares were: standard T8 (5.1%); energy savings T8 (60.0%); CFL (17.2%); metal halide (2.3%); halogen infrared (0.9%); other lighting products (11.0%); and mechanical and other products (3.6%). Program activity is quite concentrated as just two building segments (hotel/motel/start and offices) account for 45.0% of identified applications. Energy and Peak Impacts. Gross and net energy savings were estimated for program activity in the period April 1, 2007 through March 31, 2008, as shown in Table 3.11. This evaluation addressed
37
gross program savings as follows: (1) the gross savings algorithms and parameter assumptions used in the calculation of program deemed savings were reviewed and modified using BC Hydro light logger data provided by the Measurement and Verification department and reference data used by other similar incentive programs; (2) net savings were based on gross savings modified by survey based free rider and spill over rates. Evaluated energy savings are 24.7 GWh compared to program reported energy savings of 27.5 GWh. Evaluated peak savings are 3.4 MW compared to peak savings based on the program reported energy savings of 3.8 MW. Cost Effectiveness. The cost of conserved energy estimates vary quite widely across product categories. For lighting products, the cost of conserved energy varies from $0.016 per kWh for energy saver T8 fluorescent tubes to $0.048 per kWh for pulse start metal halide lamps and for photocell lighting controls. For mechanical products, the cost of conserved energy varies from $0.014 per kWh for synchronous belts to $0.060 per kWh for adjustable speed drives. Key Learnings There are four main sets of key learnings from this study. These four sets of key learnings cover the following areas: program organization and management; program planning; program delivery; and program monitoring, evaluation and reporting. Program Organization and Management. (1) Define clearly project management roles and responsibilities, so that customers and trade allies see a unified and seamless program process, and so they understand who they should turn to when there are problems or issues. (2) Adjust the program scope to reflect new opportunities and challenges in the market, while ensuring that revised program definition and strategies are clearly communicated to program staff and stakeholders. (3) Use trained and experienced engineering and technical staff. Since projects in large commercial buildings are often complex and unique to a specific site, trained and experienced staff are critical in ensuring that projects are well conceived and implemented. Program Planning. (1) Conduct adequate market research before program launch to understand market barriers and drivers, identify and build contacts with key market players, and align the goals and needs of market players and the program. (2) Develop a program plan with a clearly articulated program logic that clearly states the program objectives, operational outputs and resources required, so that stakeholders know what the program seeks to accomplish and why it has the stated objectives. (3) Ensure that program objectives are clear, well defined, measurable and achievable given available resources. Program Delivery. (1) Leverage scarce marketing dollars through partnerships and cooperation with other market players, and ensure that marketing communications are clear, simple and focused. (2) Understand product features, reliability, energy and demand savings, and product price before including the product in the program offer. (3) Ensure that incentives are an appropriate instrument in the context of the market being addressed, and that other instruments such as standards development, labeling or information are not more cost effective or appropriate given barriers to purchase for the product. Program Monitoring, Evaluation and Reporting. (1) Assess customer satisfaction through program evaluation surveys, and address both substantive material issues and problems and concerns which are identified through appropriate modifications to program design, program marketing or delivery. (2) Build systems to track sales levels and market shares, as well as their changes over time. (3) Develop appropriate algorithms to estimate energy savings and demand savings, and collect suitable data through surveys, site visits, shelf stock surveys and metering so that credible evaluation estimates can be made in a timely manner.
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York, D. and M. Kushler. 2003. America’s Best: Profiles of America’s Leading Energy Efficiency Programs, Report Number U032. Washington, USA: ACEEE, 2003.
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Decarburizing Hungarian tertiary buildings through improved energy efficiency: technological options, costs and the CO2 mitigation potential Victoria Novikova Central European University, Centre for Climate Change and Sustainable Energy Policy
Abstract Electricity consumption in tertiary buildings of new EU Member states has experienced a sustained growth over last few decades and has grown by 120% from 1990 to 2007 causing a significant increase in associated CO2 emissions [1]. At the same time, according the latest IPCC report [2], improving energy efficiency offers the largest and most cost effective mitigation opportunities in the buildings sector. However, research on available energy efficiency options, their CO2 mitigation potential and costs is limited in the region. This paper aims to bridge this gap in knowledge and summarizes results of PhD research aimed at quantifying the potential to mitigate CO2 emissions from the efficiency improvement in electricity end-use in the Hungarian tertiary sector. The paper reviews results of a bottom-up simulation model of electricity consumption and CO2 emission forecast in Hungarian tertiary buildings from 2005 to 2025 and provides analysis of the CO2 mitigation potential available in the sector and costs of CO2 abatement in 2025. The key outcome of the analysis presented in the paper is a supply curve of mitigated CO2 that relates the potential carbon savings as a function of costs per unit of mitigated CO2 emissions.
Introduction The buildings sector is the second largest global carbon dioxide emitter after industry and is responsible for one third of the total global CO2 emissions [3]. During the last five years since the IPCC Third Assessment Report [4] the average annual rate of growth of CO2 emissions from energy use in tertiary buildings have accelerated worldwide and is estimated as 3.0% in the last five-year period in contrast to 2.2% of the preceding 30-year-trend [3]. One single form of final energy responsible for the largest share of energy-related CO2 emissions from the global buildings sector has been electricity. In fact, in 2004, global CO2 emissions from electricity use in the buildings sector were 5.6 GtCO2/year, which was 65% of total global energy related CO2 emissions from the buildings sector (estimated based on [3]). Similar trends are observed in the EU-27 buildings sector, final energy consumption of which has grown by 12 % and final electricity consumption has grown by 53% between 1990 and 2007 (estimated based on [1]). This accelerated growth of electricity consumption is inter alia determined by strong development of the EU-27 tertiary sector, which has been especially pronounced in the New Member States experiencing a 120% growth of tertiary electricity demand over the same period [1]. In spite of being an important part of a global problem of climate change, the buildings sector is considered by a large body of research literature being a key part to its solution (see e.g., [2], [5], and [6]). A broad range of best practice examples demonstrate that it is possible to achieve up to 80% energy savings at low or no extra costs (see, e.g., [7] and [8]). For this reason, buildings are very often called as a ‘goldenmine’ of greenhouse gas (GHG) mitigation [9]. In order to explore this ‘goldenmine’ it is necessary to estimate the size and associated costs of GHG mitigation in order to give a clear guidance for evidence-based climate policy design. The present study aims to address this gap in knowledge and summarizes results of doctoral research aimed at quantifying the potential to mitigate CO2 emissions from electricity use in tertiary buildings of Hungary, one of new EU Member States where tertiary electricity demand has been growing at such a high rate. In order to provide information to decision makers on prioritizing investments in climate change abatement in Hungary, the study estimates the potential to mitigate CO2 emissions from improving the end-use efficiency of electricity in the Hungarian tertiary sector as a function of costs of deployment of energy efficient technologies. To achieve this aim, the following objectives have been reached: (1) modeling the baseline electricity consumption in Hungarian tertiary buildings disaggregated by enduse technologies for the period 2005-2025, (2) estimating the efficiency improvement and associated CO2 mitigation potential for each individual modeled end-use , (3) analyzing cost-effectiveness of an
40
individual mitigation option from the societal perspective, (4) constructing the supply curve of CO2 abatement as a function of the cost of mitigated CO2. Methodology developed and methods used to fulfill the objectives of the study are described in the next section.
Research design and methods For the purpose of the present study, a bottom-up engineering-economic simulation model has been developed. The development of the model includes the number of methodological steps presented in Figure 2 and described in detail below. Figure 2. The bottom-up simulation model for quantifying the CO2 mitigation potential from the efficiency improvement in electricity end-use in the Hungarian tertiary sector Database of the largest electricity consumers and the fastest growing loads
• • • • •
Technical input parameters: Unit electricity consumption; Power consumption; Time in use; Efficiency improvement rate; Lifetime;
• • •
•
Economic & market input parameters: Appliance stock; Sales growth rate; Price of a product; Price of electricity;
Baseline scenario for 2005-2025 Database of mitigation options: • • •
Electric efficiency improvement potential; Cost of each option; CO2 mitigation potential;
Calibration Mitigation scenario for 2005-2025 Supply curve of conserved CO2 Sensitivity analysis Discount rates: Electricity price growth rate: • 4% • 1.0% • 6% • 1.5% • 9% • 2.0%
Input parameters Modeling steps
The first modeling step includes simulation of electricity consumption in Hungarian tertiary buildings disaggregated by end-use technologies. For simulation of electricity consumption in the Hungarian tertiary sector all electrical end-uses have been split into four categories based on their specific functions or modes. These categories include (1) always on products, (2) on/off products, (3) on/standby products, and (4) job-based products [10]. Total electricity demand for electric services is estimated as a sum of electricity demands of individual end-uses. Based on data availability, the year 2005 has been chosen as the base modelling year, as the most recent statistical data is available for this year. The baseline scenario is defined as the growth of stocks of end-uses (determined by present and future market shares, their lifetimes and sales growth rates) and their individual electricity consumption (influenced by average annual efficiency improvement rates) over the modelling period of 2005-2025. Mitigation options considered in the mitigation scenario are targeted at improving the efficiency of electricity end-use and are restricted to technologies that are currently commercially available and can be relatively easily substituted for or applied to existing end-use technologies on a retrofit basis. To analyze cost-effectiveness of the individual technological options, the economic analysis of individual options has been conducted. In the economic analysis, cost of conserved electricity and, based on it, marginal cost of CO2 abatement is calculated. Cost of conserved electricity of the individual mitigation option is estimated taking into account cumulative country-wise annualized investment required to introduce the technological option, country-wise avoided payment for electricity resulted from introducing more efficient technological option instead of the reference one, and resulted country-wise electricity saved. Based on the results of estimates, supply curve of conserved carbon is created. The supply curve of mitigated CO2 relates the quantity of CO2 which can be reduced by mitigation options to the cost per unit of CO2 reduction.
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Data sources Over 160 various data sources have been used in the present study to collect data listed in Figure 2. These include databases of electric equipment, reports of production associations and consultancies, market studies, equipment catalogues and others (please see the author’s dissertation [11] for the full reference list) Limitations All limitations of the study can be split into limitations of the developed model and limitations of the methods used. Although the model covers all major electric end-use technologies installed in Hungarian tertiary buildings and considers around 150 mitigation options targeted at electric efficiency improvement, not all mitigation options available in the sector are considered. Only options offering the largest cost-effective mitigation potential that are commercially available or will be commercially available in the nearest future have been incorporated in the model leaving out expensive options, offering low mitigation potential or promising options in terms of CO2 mitigation, but are at a stage of laboratory testing and thus are not commercialized yet. For this reason the CO2 mitigation potential reported in the study is limited to the considered options. Limitations of the supply curve method used in the present study includes the assumption that understanding of energy services will not change over the projection period, costs considered in the method are average costs that do not reflect real costs variation in a product range, ranking of measures in the supply curve is done purely on a leastcost basis and only one of mutually exclusive options is included in the curve [2], [12].
Baseline scenario In order to construct the baseline and mitigation scenario, the equipment stock model has been built that models stocks of major types of electric appliances, equipment and lights installed in the Hungarian tertiary sector. The following types of end-uses constitute the equipment stock model: • • • • • • • • • •
Lighting; Air-conditioning; Ventilation; Refrigeration; ICT appliances; ICT infrastructure; Electric motors; Water pumps; Circulators; Miscellaneous electricity end-uses.
Present and future market shares as well as lifetime of the equipment in scope has been taken into account in order to project the equipment stock over the modeling period of 2005-2025. To forecast sectoral baseline electricity consumption, input power, time in use, efficiency improvement rate of the electric end-uses over the projection period 2005-2025 have been used to build business-as-usual scenario that is served as a reference situation. According to baseline projections, baseline electricity consumption of the Hungarian tertiary sector will increase by around 40% between 2005 and 2025 (see Figure 3). Figure 3 Baseline electricity consumption of the Hungarian tertiary sector, 2005-2025
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BAU electricity consumption
GWh 18 000
16 000
14 000
12 000
10 000
8 000
6 000
4 000
2 000
Lighting
Air-conditioning (cooling+heating)
Ventilation
Refrigeration
ICT appliances
ICT infrastructure
Electric motors
Water pumps
Circulators
Other uses
2025
2024
2023
2022
2021
2020
2019
2018
2017
2016
2015
2014
2013
2012
2011
2010
2009
2008
2007
2006
2005
0
Baseline CO2 emissions associated with electricity use in Hungarian tertiary buildings are forecasted grow by 35% over the projection period (Figure 4). The CO2 emission increase is lower than corresponding increase in final electricity demand of the sector due to future changes in the CO2 emission factor of electricity. The CO2 emission factor of electricity is expected to decline from 2005 to 2015 and rise again from 2015 due to planned putting in operation new lignite power plants [13]. Figure 4 Baseline CO2 emissions from electricity use in the Hungarian tertiary sector, 20052025 BAU CO2 emissions
MtCO2
6
5
4
3
2
1
Lighting
Air-conditioning (cooling+heating)
Ventilation
Refrigeration
ICT appliances
ICT infrastructure
Electric mo tors
Water pumps
Circulators
Other uses
2025
2024
2023
2022
2021
2020
2019
2018
2017
2016
2015
2014
2013
2012
2011
2010
2009
2008
2007
2006
2005
0
Mitigation scenario Table 2 presents summary of over 150 mitigation options targeted at key electric end-uses that have been considered in the mitigation scenario. Table 2 Summary of mitigation options considered in the mitigation scenario End-use Lighting Air-conditioning
On-mode efficiency improvement X X
Reducing standby consumption X
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End-use
On-mode efficiency improvement X X
Ventilation Refrigeration ICT appliances ICT infrastructure Electric motors Water pumps Circulators
Reducing standby consumption
X X X X X
Figure 5 illustrates the development of tertiary electricity demand over the modeling period according to baseline and mitigation technology projections. It shows that implementing all mitigation options considered in mitigation scenario allows reducing final electricity consumption by 20% in 2025. Figure 5 The development of tertiary electricity demand according to BAU and mitigation technology projections, 2005-2025 18.00
TWh
16.00 14.00 12.00 10.00 8.00 6.00 4.00 2.00 0.00 2005
2010
2015 Year
BAU electricity consumption
2020
2025
Mitigation electricity consumption
Types of end-uses offering the largest mitigation potential are lighting, air-conditioning, ICT and building circulators as shown in Figure 6. Figure 6 Equipment type contribution to cumulative electricity savings resulted from the efficiency improvement of tertiary electricity end-use, 2008-2025 Equipment type contribution to cumulative electricity savings
3.50
TWh Electric motors
3.00
Water pumps Ventilation ICT appliances Air-conditioning
2.50
Circulators ICT infrastructure Refrigeration Lighting
2.00
1.50
1.00
0.50
Year
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2025
2024
2023
2022
2021
2020
2019
2018
2017
2016
2015
2014
2013
2012
2011
2010
2009
2008
0.00
Cumulative carbon savings resulted from implementation of all considered mitigation options amount to 20% of baseline CO2 emission in 2025 (Figure 7). Figure 7 Cumulative carbon savings in 2025 6.00
5.40 MtCO2
MtCO2
5.00
4.39 MtCO2
+54 4.00
-20%
3.51 MtCO2
3.00
2.00
1.00
Base year 2005
BAU technology projection 2025
Mitigation technology projection 2025
Table 3 details on cumulative electricity and carbon savings resulted from the efficiency improvement in electricity end-use in the Hungarian tertiary sector. It also gives details on cost of electricity conservation and mitigation CO2 emissions. Table 3 Carbon and electricity savings and respective costs of mitigated CO2 in 2025 from the efficiency improvement of tertiary electricity end-use Cost of Cost of CO2 Electricity mitigated electricity savings in savings in CO2 in saving in Measure 2025 2025 2025 2025 ktCO2/yr. Efficient Lighting Efficient Air-conditioning (cooling+heating) Efficient Ventilation Efficient Refrigeration Efficient ICT appliances Efficient ICT infrastructure Efficient Electric motors Efficient Water pumps Efficient Circulators
243 154 108 92 45 134 14 17 206
EUR/tCO2
GWh/yr.
-608 -397 -382 -433 -386 -416 1162 -81 -407
745 472 330 282 138 411 40 52 631
EUR/kWh -0.198 -0.130 -0.125 -0.141 -0.126 -0.136 0.379 -0.027 -0.133
Supply curve of mitigated CO2 In order to provide decision-makers with clear guidance on cost-effectiveness of CO2 mitigation from the efficiency improvement in the tertiary sector, all mitigation options are ranked according to their cost-effectiveness and amalgamated into the CO2 abatement cost curve presented in Figure 8. The figure shows that almost all key electric end-uses of the Hungarian tertiary sector offer a significant and cost-effective CO2 mitigation potential available at negative and low abatement costs. Figure 8 Aggregate abatement cost curve for the Hungarian tertiary sector
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Aggregate abatement cost curve for the Hungarian tertiary sector
Efficient motors
0 0 -100
200000 Abatement cost Euro/tCO2
400000
600000
800000
1000000
1200000
Efficient water pumps
Efficient ventilation -200
Reducing LOPOMO of ICT appliances Efficient air-conditioning
-300
Efficient curculators Efficient ICT infrastructure Efficient refrigeration
-400
-500
Efficient lighting -600 Cumulative abatement potential tCO2 -700
In order to achieve the identified CO2 mitigation potential, a cumulative investment of 2.2 billion Euro is needed that will return 5.6 billion Euro in terms of saved electricity costs over the period from 2008 to 2025.
Conclusion Climate change is one of major global challenges the world faces nowadays. Being the second largest emitter of CO2 emissions, the buildings sector is a part of this global problem. It can also be a part of its solution as it offers a large cost-effective CO2 mitigation potential. To inform the evidence-based climate policy design aimed at tapping the mitigation potential available in the sector, a detailed knowledge on the size and the cost of CO2 abatement needs to be provided to policy-makers. The present study aims to fill this gap in knowledge and provides detailed information about the CO2 mitigation potential from the efficiency improvement in electricity end-use in the Hungarian tertiary sector as a function of costs of carbon abatement. To fulfill this research goal, the author developed a technology-rich bottom-up simulation model (for more detailed description of the research results see [11]). The author developed a forecast of electricity demand of and associated CO2 emissions from Hungarian tertiary buildings over the period 2005-2025, identified key electric efficiency improvements available in the sector and costs associated with their implementation, evaluated cost-effectiveness of the identified options, and constructed a supply curve of mitigated CO2 emissions. The study concludes that electricity demand of the Hungarian tertiary sector is expected to grow by around 40% and increase from 9.9 TWh in 2005 to 16.5 TWh in 2025. The associated sectoral CO2 emissions will grow by 35% from 3.5 to 5.4 MtCO2 over the same period. A slightly disproportional increase of CO2 emissions compared to electricity demand is attributed to future changes in the CO2 emission factor of electricity related to planned changes in electricity mix as reported by [13]. The research shows that it is possible to cost-effectively mitigate 20% of CO2 emissions in 2025 if the efficiency of major electric end-uses is improved. To realize this mitigation potential a cumulative investment of 2.2 billion Euro is needed that will return 5.6 billion Euro in terms of saved electricity costs over the period from 2008 to 2025. This information on the CO2 mitigation potential, required investment and saved electricity costs can be a good investment schedule for decision makers that allows prioritizing investments in climate change abatement in Hungary. It also represents a clear guidance for policy makers on the size of the available mitigation potential and costs the society needs to pay for the abatement.
46
References [1]
Bertoldi, P. and Atanasiu, B. 2009. Electricity consumption and efficiency trends in European Union. Status report 2009. Luxembourg: Publications Office of the European Union.
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Levine et al 2007 Levine, M., D. Ürge-Vorsatz, K. Blok, L. Geng, D. Harvey, S. Lang, G. Levermore, A. Mongameli Mehlwana, S. Mirasgedis, A. Novikova, J. Rilling, H. Yoshino, 2007: Residential and commercial buildings. In Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
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Price, L., De la Rue du Can, S., Sinton, J., Worrell, E., Zhou, N., Sathaye, J. and Levine, M. 2006. Sectoral Trends in Global Energy Use and Greenhouse Gas Emissions. Lawrence Berkeley National Laboratory, Berkeley, CA.
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Intergovernmental Panel on Climate Change (IPCC) 2001. Climate Change 2001: Mitigation. Contribution of Working Group III to the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). B. Metz, O. Davidson, R. Swart, and J. Pan [eds.]. Cambridge University Press. Cambridge, United Kingdom and New York, NY, USA, 752 pp.
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UNEP (United Nations Environmental Programme) 2007. Buildings and Climate Change: Status, Challenges, and Opportunities. UNEP.
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International Energy Agency (IEA) 2006a. World Energy Outlook 2006. Paris: IEA.
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Öhlinger Ch. 2006. 50,000 Energy performance certificates for buildings. Presentation at the European Energy Efficiency Conference in Wels, Austria, March 1–3, 2006.
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Harvey, L.D.D. 2006. A Handbook on Low-Energy Buildings and District Energy Systems: Fundamentals, Techniques, and Examples. James and James, London.
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Fraunhofer IZM 2007. EuP Preparatory Study ‘Standby and Off-mode Losses’ (Lot 6). TREND/D1/40 Lot 6-2005
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Novikova V. Forthcoming. The economic potential of carbon dioxide emission mitigation from the efficiency improvement in electricity end-use in the Hungarian tertiary sector. PhD dissertation. Budapes: Central European University
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Rufo, M. 2003. Attachment V – Developing Greenhouse Mitigation Supply Curves for In-State Sources, Climate Change Research Development and Demonstration Plan. For the California Energy Commission, Public Interest Energy Research Program, P500-03-025FAV.
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MAVIR, 2005. A villamosenergia-rendszer közép- és hosszú távú forrásoldali kapacitásterve [Medium and long term capacity plan for the demand side of the electricity system].
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Energy savings potential in the Hungarian public buildings for space heating Katarina Korytarova and Diana Ürge-Vorsatz Central European University
Abstract According to IPCC the largest amount of cost-effective mitigation potential is in the building sector. Most of the studies, however, focus on the residential sector, and only few on non-residential buildings. This paper describes the results of energy savings and mitigation potential analysis in the Hungarian public sector for space heating. The abatement options include improvement of energy efficiency of building envelope and heating system, heat controls and passive energy standard for new construction. The baseline energy use is based on the results of energy audits collected under UNDP/GEF project for municipal buildings. Energy savings potential is determined using two different approaches. According to the well-established component-based approach more than one third of the 2030 energy use can be reduced cost-effectively which is in line with other studies of this type. The rather new, performance-based analysis shows that 3 times higher total potential can be achieved by gradual phase-in of passive energy standard to both existing and new buildings. Based on this approach, several scenarios are constructed to analyze the impact of different rates of retrofit and performance levels on energy savings, mitigation potential and cost-effectiveness. The study shows that although the rate of retrofit is a significant factor for the total potential, it is even more important to what level of energy performance buildings are built or retrofitted. The study shows that if existing buildings are retrofitted at an accelerated rate only partially, the resulting potential will be only slightly higher than if buildings are retrofitted at natural rate of retrofit to passive energy standard.
Introduction The impacts of the climate change can be already observed. In order to prevent further and irreversible changes in climate and environment, IPCC recommends to keep the global average surface temperature increase below 2ºC relative to pre-industrial levels, which translates into 50-85% by 2050 compared to current (2000) levels [Box 3.10, 1]. This means that in the short term CO2 emissions should be reduced by 20-40% by 2020 relative to 1990 levels [Box 13.7, 2]. Therefore, several countries have committed to targets on reducing greenhouse gas emissions and targets on reducing energy consumption as one of the key emitters of CO2 emissions. The EU has made a commitment to avoid the dangerous climate change and limit the warming of the average surface temperature below 2ºC compared to pre-industrial levels [3]. Within its climate-energy package the EU set a 20% reduction target for its energy consumption by 2020 compared to 1990 [4]. At the same time, energy resources are scarce and the energy prices are increasing due to instability in energy supply. Several countries invest into energy efficiency to improve the energy security for their economies. Moreover, energy efficiency not only decreases the energy costs for the end-users, but also provides several other non-financial co-benefits, such as improved indoor air quality and thermal comfort, increased productivity and other. Although the need for the required emission and energy reductions is large, there is a significant potential for reducing the energy in different sectors of the economy in cost-effective way. Buildings offer especially large potential at zero and negative costs [5]. The main aim of the presented research is to determine the energy savings potential in the public buildings in Hungary. Among the research objectives is to find the optimal pathway towards lowenergy, low-carbon economy and to provide insights into the risk of the lock-in effect when buildings are retrofitted to suboptimal level. The structure of the paper is following: first, the energy savings potential is shown from two different perspectives, and then the results of the scenario analysis, including the lock-in effect is discussed.
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Determination of energy savings potential by two approaches Most of the reviewed studies focusing on building sector use bottom-up modeling framework (for example [6, 7, 8, 9, 10,11]. These studies rely on the component-based approach which calculates the total energy savings potential based on the potentials of the improved individual building components. Although this approach is by now well-established in the area, it is often criticized for not considering energy savings potential from the holistic point of view. Holistic point of view means that all systems in the building are considered together, result of which is that the building as a whole is treated as a system itself. This can be done through integrated design - “a process in which all of the design variables that affect one another are considered together and resolved in an optimal fashion” (Lewis 2004 cited in 12). A holistically-oriented alternative is performance-based approach, which has been already used in building codes in several countries and is increasingly popular – several countries have published their plans to implement some performance based building standards in the future. [13, 14] have calculated the energy savings that can be achieved by applying these performance standards in several countries by using a simple performance-based model for new buildings. The current study uses bottom-up modeling framework with both component-based and performance-based approach for both existing and new buildings. While the component-based approach looks at the energy savings achieved by the individual building components, the performance-based approach considers the building as a whole. The componentbased approach shows the cost-effectiveness of the individual measures. On the other hand, the performance-based model determines the potential on the basis of the energy performance of the building and compares cost-effectiveness in different building types. Both approaches use the same building stock projections, building typology and specific heating energy requirements for the existing buildings (built until 1990). Hungarian public buildings are divided into eight main building types based on their function and size: small educational buildings (kindergartens and nurseries), large educational buildings (primary, secondary and tertiary educational buildings), small health care buildings (doctor’s offices and ambulance stations), large health care buildings (hospitals, medical centers etc.), small and large public administration buildings, social buildings (homes for elderly, orphanages), cultural buildings (museums, community centers). The building stock for year 2005 is based on publications and online database of the Hungarian Central Statistical Office [15, 16]. The future building stock is projected based on relevant historical indicators which vary by subsector, and are usually linked to the population. Among the indicators are number of children in kindergarten per 1000 inhabitants, students in primary, secondary and tertiary education per 1000 inhabitants, number of beds in hospitals per 10,000 inhabitants etc. The building typology is based on the observation of the buildings listed in the energy audits (see below), and the average floor area per building type. The specific heating energy requirements are based on a sample of energy audits collected from UNDP/GEF municipality project [17] and other sets of audits [18, 19]. The analysis of the energy audits shows that in general the large, multi-storey buildings use less energy than the small, onestorey buildings (Figure 9). This is in line with the premise that compact buildings (buildings with low A/V ratio) have a better energy performance. This premise, however does not hold for small and large health care buildings – high average daily temperatures and long working hours offset the low (suitable) A/V ratio in the large buildings (hospitals), and the large (unsuitable) A/V ratio in the small health care buildings (doctor’s offices, ambulance stations) offsets the relatively low temperatures and shorter working hours.
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Figure 9 Specific energy requirements of the Hungarian public buildings (kWh/m2.a) Specific energy requirements of Hungarian public buildings (kWh/m2.a) 400 2
kWh/m .a 350
300 "Other" Water heating Space heating
250
200
150
100
50
0 Kindergartens
Primary & secondary schools
Doctor's offices
Hospitals & medical centres
Small public Large public administration administration
Social buildings
Cultural buildings
Source: UNDP/Energy centre (2008), Nagy (2008), Csoknyai (2008) Note: ‘Other’ includes mainly lighting and appliances. The most energy intensive are social care buildings (homes for elderly, orphanages) due to their high temperatures and day-long working hours. The most efficient in terms of space heating are public administration buildings followed by the large educational buildings, mainly because of the building compactness and shorter working hours. Based on this common basic framework the business-as-usual (BAU) and mitigation scenarios are constructed under each approach. Component-based approach The BAU scenario in the component-based approach is based on the assumption that the considered energy savings measures are applied at natural rate of retrofit [1% p.a., based on 20, 21] 16. These include improving building envelope and replacement of the old boiler by a standard boiler (based on [10], [22] and product catalogues [23]). In the mitigation scenario all existing public buildings are assumed to be retrofitted by 2030. In addition to the BAU measures, temperature management is included and the old boiler is replaced by a more efficient, condensing boiler. New buildings are assumed to become passive by 202017 and this part of the model is the same as in the performancebased model. The component-based approach works on the basis of cost curve method. The advantage of this method is that when adding up the energy saving potentials of the individual measures together, the overlap of the potential of the interrelated measures is avoided. The costs of the different technology options are based on [20], [10], product catalogues and consultations [22]. Cost learning is assumed for high-performance windows and passive new construction. The results of the analysis show that about 34% of the baseline 2030 energy use can be reduced cost-effectively. This means that for 16
This is also in a line with the assumptions in [20], where the rate of retrofit is 1.2% for North-Western Europe, 0.9% for Southern Europe and 0.7% for Member States which joined EU in 2005 (including Hungary) in 2004. This is assumed to increase to just above 1% in 2010 for the Member States of 2005 accession [21]. 17
This assumption is based on the proposal for the recast of the EPBD directive in time of conducting the research, which requires countries to set targets for share of buildings which become low-carbon or low-energy by 2020 [24].
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those measures the energy cost savings offset the initial investment costs over the lifetime of the measure. The most cost-effective measures are temperature management, insulation of the external wall and exchange of windows (Figure 10). According to experts, over 80% of all public buildings are overheated and can lower their average temperature by 2ºC [25]. Installation of a condensing boiler is the least cost-effective option. The results of this method may be understood in such a way that only the most cost-effective measures should be applied. However, only a holistic approach to retrofit including simultaneous insulation of walls, exchange of windows and renovation of heating systems provides better thermal performance and lower risk of fabric damage [26]. Thus, less cost-effective options should be implemented during the retrofit as well, together with the most cost-effective measures, so that full potential of the applied measures can be achieved. Figure 10 Average supply cost curve for the Hungarian public buildings for space heating 200
Euro/t CO2 150
Condensing boiler
Insulation of basement
100
Roof insulation
50
kt CO2 0 0
100
200
-50
300
Wall insulation in small buildings
400
500
600
700
800
Passive energy standard
-100
Window exchange -150
-200
-250
Wall insulation in large industrialized buildings
Baseline CO2 emissions in 2030: 1524 kt CO2
Temperature management
-300
Performance-based approach The BAU scenario in the performance-based approach assumes that the existing buildings (built until 1990) are retrofitted at the natural rate of retrofit (1% p.a.) either to level of partial retrofit (23% energy savings compared to existing buildings built before 1990; based on [27]) or to the level of the 2006 Building code [28] (50% energy savings relative to the existing buildings, [29]). These assumptions are based on the observation that in Hungary an increasing number of buildings is retrofitted to a low level of retrofit and only part of the renovated buildings are retrofitted to the level of 2006 Building code. However, it is assumed that the share of the 2006 Building code on the total number of retrofitted buildings is increasing over time. All new buildings are assumed to be built according to 2006 Building code. In the mitigation scenario (referred to as Passive accelerated scenario), three levels of energy building performance are considered – 60kWh/(m2.a) level referred to as 2011 standard, 30 kWh/(m2.a) level referred to as low energy standard and 15 kWh/(m2.a) referred to as the passive energy standard. It is assumed that all existing buildings are retrofitted by 2030. The majority of the retrofitted buildings gradually implement passive energy standard by 2020, while the rest (those which cannot be retrofitted to such high level, such as historical buildings, buildings with unsuitable orientation) constitutes of the 2011 standard and low-energy standard. For the new construction it is assumed that all buildings are built to the level of passive energy standard by 2020, assuming a similar transition through the low energy and 2011 standard as in the retrofit. Technical and cost assumptions are based primarily on [27, 28, 29, 30, 31, 32, 33] and other sources. Technology learning is assumed for all mitigation measures (i.e. 60kWh/m2, low-energy and passive standard). 52
The performance-based approach shows that the most cost-effective potential occurs in retrofitting of the social and health care buildings, which belong among the most energy intensive buildings. These are followed by new construction in social and health care sectors (Figure 11 and Figure 12). Figure 11 CO2 mitigation potential in terms of the cost of CO2 reductions for retrofit of existing buildings Passive accelerated scenario: CO2 mitigation potential for retrofit (Euro/t CO2) 0 0
Euro/t CO100 2
200
300
400
500
600
700
800
900
1000 kt CO2
-50
-100 Small administration buildings -150
Large administration buildings
Large educational buildings
Cultural buildings
Small educational buildings Small health care buildings
-200
Large health care buildings
Baseline CO2 emissions for space heating in 2030: 1518 kt CO2
Social buildings
-250
Figure 12 CO2 mitigation potential in terms of the cost of CO2 reductions for new construction Passive accelerated scenario: CO2 mitigation potential for new construction (Euro/t CO2) 350 Euro/t CO2
Large administration buildings
300 250 Small administration buildings
200 150
Cultural buildings
100 50
kt CO2 Large health care buildings
0 0 -50 -100
20 40 Small health care buildings Small educational buildings
-150
60
80
100
120
140
160
180
Large educational buildings
Baseline CO2 emissions for space heating in 2030: 1518 kt CO2
Social buildings -200
Large health care (hospitals and medical centers), large educational (primary, secondary and tertiary education) and social buildings provide the largest potential. 53
Comparison of the component-based and performance-based approach revealed a large gap between these two approaches. While the component-based approach provides approximately 44% energy savings compared to 2030 baseline, the performance-based approach results in 73% energy savings relative to the baseline in 2030 (Figure 13). Figure 13 Comparison of the energy saving potential between the component-based and performance-based modeling approach Comparison of component- and performance-based approach (GWh) 12 000
10 000
GWh/year
8 000
6 000
BAU scenario MIT: Component-based MIT: Passive accelerated
44%
4 000 73%
2 000
20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21 20 22 20 23 20 24 20 25 20 26 20 27 20 28 20 29 20 30
0
The difference in the results of the two approaches is mainly due to difference in the build-up of the two modeling approaches. While in the component-based model only one abatement option is applied at one point in time, in the performance-based model several performance levels may be in place in parallel. The difference can also be explained by the differences in setting the BAU scenario for the existing buildings in the two approaches. In the component-based model the BAU is constructed by applying selected individual measures to the frozen efficiency scenario, while the share and technical parameters of these measures are the same over the projection period. In addition, the technical features of the measures in BAU scenario are the same as in the mitigation scenario except for the condensing boilers and temperature management, and only the rate of retrofit is different from the mitigation scenario. However, the BAU scenario of the performance-based approach is constructed based on the assumption of combination of two performance levels (the prevailing partial retrofit and a retrofit with 50% energy savings – the 2006 Building code) - and thus assumes two different technologies. The two approaches are compared on basis of the performance-based BAU scenario (Figure 13). The analysis showed that the performance-based modeling tools can provide a flexible support tool for the energy and climate policy makers. Its flexibility lies in the possibility to set different performance levels to be implemented with consideration to timing of phase-out of the existing performance levels and gradual phase-in of the new levels. Several performance levels can be set to be implemented to the same building stock in parallel. Although this may be possible in componentbased approach as well, it is very labour intensive (especially in Excel-based model) and lacks flexibility which is often needed in decision making in order to see alternative outcomes given varying assumptions. Thanks to this flexibility, the performance-based approach is used further for the scenario analysis.
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Scenario analysis – different pathways to low-energy future The aim of the scenario analysis is to show the risks of mass application of the suboptimal retrofit in the public building sector. Once the buildings are retrofitted to suboptimal level, they will not be renovated again for several next decades until major renovation is needed again (the renovation cycle in Hungary is about 30-50 years, [29]). This way the energy consumption remains on relatively high level until the next renovation and thus, the emissions are locked-in in the current infrastructure for several next decades. The effect of the lock-in effect can be determined as the difference between the most energy efficient scenario and the suboptimal scenario. In addition to these two scenarios, another scenario is constructed, which aims to show the effect of the gradual phase-in of the passive energy standard applied to only 1% of the existing building stock per year (natural rate of retrofit). Table 4 shows the main assumptions of the considered scenarios. Table 4 Basic assumptions for the scenario analysis Existing buildings BAU scenario
Passive accelerated
Passive 1%
Suboptimal accelerated
•
Natural rate of retrofit (1% p.a.)
•
Partial retrofit and 2006 Building code
•
All existing buildings retrofitted by 2030
•
Gradual phase-in of passive energy standard to majority (85%) of the existing building stock by 2020
•
Natural rate of retrofit (1% p.a.)
•
Gradual phase-in of passive energy standard to majority (85%) of the retrofitted building stock by 2020
•
All existing buildings retrofitted by 2030
•
Partial retrofit only (23% energy savings compared to existing buildings)
New buildings 2006 Building code
Gradual phase-in of passive energy standard to the whole building stock by 2020
Gradual phase-in of passive energy standard to the whole building stock by 2020
Gradual phase-in of passive energy standard to the whole building stock by 2020
The results show that the Passive 1% scenario provides the lowest potential, which is, however, only slightly lower than the Suboptimal accelerated scenario. Passive accelerated scenario provides three times higher potential than either of the two previously mentioned scenarios (
55
Figure 14).
Figure 14 Comparison of BAU and three mitigation scenarios (GWh) Final energy for space heating (GWh) Hungarian public building sector (2005-2030) 12 000
10 000
8 000 GWh/year
20%
22%
6 000
BAU scenario MIT: Passive accelerated
73%
MIT: Passive 1%
4 000 MIT: Suboptimal accelerated 2 000
20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 21 20 22 20 23 20 24 20 25 20 26 20 27 20 28 20 29 20 30
0
The most important message from the scenario analysis is that the energy savings from the suboptimal scenario are only slightly higher than those of the Passive 1% scenario. This is important taking into consideration the effort which is put into retrofitting of the whole building stock (scaffolding, involvement of the work force), i.e. the fixed costs of the retrofit. On the other hand, in the Passive 1% scenario only 1% of the whole existing building stock is retrofitted annually and it has a similar effect as a large-scale partial retrofit. This means that not only the rate of retrofit is deterministic for the total achievable and cost-effective potential but even more important is the level to which the buildings are retrofitted. When buildings are retrofitted to the suboptimal level and even the whole stock is retrofitted the total effect will be similar as if only the part of the stock is gradually retrofitted to passive energy level. However, once the optimal level for retrofit is determined and a feasible timing and transition period is decided, this level of retrofit should be applied to the whole existing building stock. In this case the rate of retrofit can make a large difference – by increasing retrofit rate from 1% p.a. to about 4% p.a. more than 3 times higher energy saving potential can be achieved.
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The difference between the energy savings potential of the Passive accelerated scenario and the Suboptimal accelerated scenario is about 50%. This means that applying the more ambitious scenario can bring additional 50% energy savings relative to 2030 baseline. Other way round, by applying partial retrofit to the whole building stock by 2030 energy saving potential of 50% (relative to 2030 baseline) can be lost. This difference represents the lock-in effect of the suboptimal scenario – the emissions that are locked in the infrastructure until the next renovation cycle. Moreover, the cost analysis shows that the Suboptimal accelerated scenario is not even costeffective, meaning that the energy cost savings do not offset the initial investment for implementation of the applied measures (Table 5). This only supports the argument that partial retrofit should not be applied to the whole building stock, neither that there should be any financial support given for partial retrofit, which would otherwise increase the demand for this kind of retrofit. Both Passive 1% and Passive accelerated scenarios are cost-effective. Due to higher energy savings achieved in the Passive accelerated scenario the financial savings are much higher than the initial investment as compared to Passive 1% scenario. Table 5 Energy savings and CO2 reduction potential in the three mitigation scenarios Energy savings CO2 emissions Energy Energy saving CO2 Business- saving potential CO2 mitigation as-usual potential in year Business- mitigation potential in year in year 2030 (% as-usual potential 2030 (% 2030 2030 of BAU) 2030 2030 of BAU) Scenario/Unit GWh GWh GWh kt CO2 kt CO2 kt CO2 Suboptimal accelerated 7 633 1 667 22% 1 518 331 22% Passive 1% Passive accelerated
Investment vs. savings Cumulative Total energy cumulative cost investment savings (2011(20112030) 2030) Billion Billion Euro Euro 1.82
0.97
7 633
1 518
20%
1 518
302
20%
0.84
0.88
7 633
5 572
73%
1 518
1 108
73%
2.62
3.24
Conclusions Buildings provide large cost-effective potential for deep reductions provided proper measures are taken already today. The aim of the paper is to investigate the extent of cost-effective potential in the public buildigns in Hungary and to quantify the so-called „lock-in effect“. Two modeling approaches are used for calculating of the energy savings potential – a wellestablished component-based and a new performance-based approach. The results show significant difference between the two which can be mainly explained by the method of implementation of the mitigation measures. The performance-based approach shows significantly higher energy savings potential than the component-based. The performance-based model is suitable for modeling several performance levels (i.e. several types of the same measure) at the same point in time. This feature provides a greater flexibility to set assumptions, such as phase-in and phase-out dates, length of the transition period. On the other hand, the designers and planners have to use more sophisticated tools to decide on the right mix of components so that in total the building as a whole does not exceed the required performance level. The performance-based model is used to construct several scenarios. The aim of the scenarios is to quantify the lock-in effect of the suboptimal accelerated retrofit of the existing building stock. The results show that the lock-in effect, the difference between the application of passive energy standard and suboptimal level to the whole existing building stock, is up to 50% of the 2030 baseline energy consumption (or almost 2/3 of the total potential). The energy savings potential of the suboptimal retrofit is only slightly higher than if the passive energy standard is gradually phased-in at only 1% 57
annual retrofit rate by 2030. In addition, unlike both of the passive scenarios, Suboptimal accelerated scenario is not cost-effective. The energy costs savings under the Passive accelerated scenario can bring energy savings costs that are several times higher than the investment costs of its implementation, which means greater benefit for the end-user. The results imply that the retrofit rate is not the most deciding factor for the total and cost-effective potential. More important is the level of performance to which the building is retrofitted. Once the performance is set to the optimal level then the retrofit can be applied to the whole building stock. Subsidies should be applied only to the most ambitious levels, so that the currently applied suboptimal level does not lock-in the high energy use in the existing buildings for several next decades. Implementation of the Passive accelerated scenario requires a strong commitment in form of a longterm strategy, and the plan to phase-in the passive energy standard for both new and existing buildings has to be announced well in advance so that the construction industry can adjust to these new targets. Although there are already plans to phase-in the near-to-zero energy buildings in the recast of the EPBD directive, this is only valid for the new construction [24]. However, most of the potential occurs in the existing buildings. Moreover, large number of existing buildings in Central Europe needs renovation. This offers opportunity to avoid the lock-in effect if passive retrofit is strongly promoted. This scenario can be only realized in an environment with a strong enforcement and incentives for the early uptake of low-carbon technology. As the energy efficiency in municipalities is usually hindered by lack of capital for the initial investment, relevant legislation should be passed to overcome these barriers and suitable financial schemes should be offered to the municipalities. Last but not least, in the transition period, architects, planners and designers should be educated in areas such as integrated design, principles of sustainable energy design, use of optimization programs for selecting the right components fitting the required performance levels, as well as life cycle energy and material use and the related emissions.
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EESI – European Energy Service Initiative: Challenges and Chances for Energy Performance Contracting in Europe Susanne Berger Berliner Energieagentur GmbH
Abstract According to the European Commission, more than 20% of EU’s energy consumption is wasted through inefficiency. A large part of the available energy saving potential lies within buildings. This potential can be effectively targeted using energy services and other energy end-use efficiency measures. Market based instruments are very effective tools to tap large economic saving potentials. Energy Performance Contracting (EPC) is such a tool. In an EPC project, an Energy Service Company (ESCO) provides its know-how and financial resources to implement adequate energy efficiency measures and takes on the performance risk to ensure that the stipulated energy savings are achieved. The investment is refinanced through the savings achieved. Good practice examples such as the Berlin Energy Saving Partnership outline the advantages of EPC. The European Energy Service Initiative (EESI) will broadly promote the implementation of EPC, contributing strongly to the establishment of effective energy service markets in Europe. Results from the current market analysis in selected European countries show the European market for EPC as very heterogeneous. Some countries have well developed markets with several large ESCOs acting in it. Other countries are at a very early stage of development and some can be characterized as emerging markets. This paper discusses challenges for European market development and contains an overview about the future perspectives of advanced EPC.
1. Energy efficiency in Europe According to the European Commission, more than 20% of EU’s energy consumption is wasted through inefficiency. In times of rising energy prices and global climate change this waste of energy is economically, environmentally and socially unjustifiable. The growing energy import dependency, depletion of fossil fuels and the fear of energy shortages foster the need for a considerable increase in energy efficiency. Next to expansion of renewable energies, energy efficiency is the major key for a more sustainable energy supply in the future. An increase in energy efficiency leads to improvements in energy security and to the establishment of future-oriented markets for energy efficient products and technologies. For this reason, the European Parliament and the Council adopted the Directive on Energy End-use Efficiency and Energy Services in 2006. One of the crucial points of the directive is the target of energy end-use reduction of 1 % per year [1]. All member states were required to set up national energy efficiency action plans (NEEAP) to use as a strategy reach saving targets. The directive sets energy saving targets for the Community of 9% until 2016. Parallel to the Directive, the EU published the Action Plan for Energy Efficiency which serves as the strategic framework for tapping energy saving potentials. Energy efficiency is clearly marked as the “key element in Community energy policy” [2]. The realization of energy saving potentials is a cost-efficient way to secure a more sustainable use of energy and reduce carbon emissions. A large part of the available energy saving potential lies within buildings. Energy efficiency in buildings leads to budgetary savings and contributes to climate protection and security of energy supply. For the implementation of energy efficiency, various instruments can be applied. Market based instruments are a very effective tools to tap large economic saving potentials. Energy Performance Contracting (EPC) is such a tool. In an EPC project, an Energy Service Company (ESCO) provides its know-how and financial resources to implement adequate energy efficiency measures and takes on the
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performance risk to ensure that the stipulated energy savings are achieved. The investment is refinanced through the savings achieved.
2. Energy Performance Contracting – cost-efficient energy savings Energy Performance Contracting means operating (and financing) procedures for the provision of building-specific energy services. These procedures aim at saving energy and cutting costs by modernising and optimising necessary functions of building automation installations and entire buildings. Energy Performance contracting (also called energy saving contracting) deals with the optimisation across trades of automation installations in buildings and building operation by a contractor in the form of a co-operation based on partnership. The aim is to achieve the guaranteed improvement of results in particular with regard to economic efficiency, energy saving, net asset value of the buildings and building conditioning. The main distinguishing feature is the financing of the investments via the guaranteed cost savings achieved through improved energy efficiency within the terms of the contract. Performance components of the contractor are financing, planning and installation of components for energy generation, distribution and usage as well as their operation and maintenance. Integration and training of the users are usually part of performance contracting. The remuneration for the services consists of a payment which is determined in dependence on the savings achieved. Fields of application are objects of existing buildings, the most favourable customer group in Europe is the public sector. Several buildings may be combined into a building pool.
3. Market overview and current situation of EPC in selected European countries The European market for EPC is very heterogeneous. Some countries have well developed markets with several large ESCOs acting in it. Other countries are at a very early stage of development and some can be characterized as emerging markets. 3.1 Further developed European EPC markets Within the diverse market situation for energy services, Germany and Austria are certainly the pioneers for Energy Performance Contracting. Both countries have high market standards and a constant market development with a relevant number of ESCOs acting on it. In the last years many successful EPC projects have been implemented. Germany has a growing market for Energy Services and is one of the pioneers for developing the European market for Energy Performance Contracting (EPC). There are already high market standards and consistent market volume and growth for both primary types of contracting – Energy Performance Contracting and Energy Supply Contracting. There is an immense economic usable potential with about 1.4 million buildings or objects for Contracting, but only between 5 – 7 % is currently used. For the future the annual turnover is roughly estimated between €1.8 and €4.5 billion. Public sector remains the most favourable customer group for EPC. The potential of investment volume for EPC in the public building sector is of about €2 billion with an annual saving potential of more than about €200 million. In the same time, Germany encounters some bottlenecks for further development of EPC in the public sector: lack of information, long project duration, the integration of constructional refurbishment measures, transaction costs, mere focus on financial aspects. Further development of EPC models and contracts, standardisation, simplification, transparency, flexibility, and further adaptation of customer needs are challenges for the actors of the energy service market. In the last 10-15 years EPC has become a popular tool Austria to optimise and modernise federal and municipal buildings. Since then, more than 1,000 buildings have been energy-optimised with this tool. Most of these contracts are still active and successful. As of 2006, there were around 30 ESCOs in Austria and the number is still increasing, though only 5 companies cover 70-80% of the total market. The estimates are of €500 million investment opportunity in economically feasible projects for the rationalization of energy use. One remarkable point, however, is that nearly all of these buildings belong to the public (federal and municipal) administration. More effort it is now given to increase the number of ESCO projects in the
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private sector; the building owners and/or users still lack awareness about the opportunities offered by ESCOs. In Sweden some 50-60 municipalities out of 290 have carried out EPC projects. In addition, a number of county councils and regions have carried out EPC projects. A survey of some 20 public property owners who had used EPC, found that the average saving achieved was 22% of energy end-use, although individual projects varied between 17% and 66%. Since only a small percentage of the total area of Swedish public property has been included in EPC, the potential is deemed great in the public sector. The Swedish Association of Local Authorities and Regions takes an active role in authoring guidelines on EPC and advising its members. There are three large EPC providers in Sweden, and a couple of smaller newcomers who have won some contracts. The EPC market in the Czech Republic can be characterized as moderately developed in the sense that the ESCOs have a good knowledge and experience in carrying out EPC. Nevertheless, still the number of projects is not high and there are no rules for EPC implementation in the public sector (namely institutions run directly by the state). So far most projects have been realised in the public sector, more specifically in the education and health care facilities. The first EPC projects were carried out already in 1993. Since then, some 150 to 200 EPC projects have been already realized. In the last years, the average value of projects was ca. € 2 million. The main types of measures under EPC are complex building refurbishments. The savings are typically ca. 20 – 30 %. The main challenges and thus also space for improvement lies in the political framework of EPC. More support on the policy level is needed. Development of standard documents and its dissemination would help in developing the EPC market.
3.2 Less developed and emerging European EPC markets The Norwegian EPC market is immature and small. There have been sporadic occasions of EPC or similar projects over the last 15 years. Various companies have offered versions of “energy saving with guaranteed results”, but the market response has not been high. Some pilot projects on outsourcing or result based contracts have been initiated through an EU/SAVE project, mainly in the private sector, but the contents differ from the EPC concept as defined by EESI. The main barriers are lack of knowledge, time and trust in EPC. Establishment of EPC projects is time demanding Low energy prices over the last few years and expected for the coming years result in low interest in energy measures, and the recent financial crisis has lead to less interest from the banking sector. Focus on climate both in media and in municipalities through Climate plans (not mandatory but strongly encouraged) however leads to focus on energy use in public buildings, where EPC can be a strong tool. Marketing of success stories and templates and training will counteract these, and funding for project establishment would be a strong positive force in developing the market. The Romanian ESCO market is in an “embryonic state”, with few companies willing to enter the market. Currently there are two companies – one specialized in electricity and the other in thermal services – which qualify as private ESCOs that offer pure EPC solutions. In addition, there is one ESCO-type company chiefly working with CHP projects. Today, some EPC is implemented in the industrial sector In spite of efforts, the ESCO market has not been able to get off the ground because of a number of strong barriers. The Belgium market Currently there are only a few (± 5) true EPC projects realized (schools and hospitals) and roughly 6 large and some smaller ESCOs in Belgium. A major step was the creation of FEDESCO in 2005 by the Federal government: a public ESCO focused on energy savings projects in federal buildings, using third party financing; exclusive right to apply third-party financing to federal buildings
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4. Good practices The City of Berlin in partnership with Berlin Energy Agency (BEA) developed in 1996 the so called “Berlin Energy Saving Partnership” (ESP), which offers efficient refurbishment of public buildings with the pivotal advantage to release building owner of any investment costs. Due to releasing building owners from expenses and delivering savings immediately, ESPs are very successful. An Energy Service Company (ESCO), which is to be determined through tendering, finances and implements appropriate energy saving investments to achieve pre-defined energy and cost reductions. In their bids, ESCO’s put together their investments targeted at delivering specified energy savings and respective CO2-reductions. Until today, 1,300 buildings shared on 24 EPC contracts have been upgraded, delivering CO2reductions of nearly 68,000 t/a. With these investments total guaranteed cost savings of about € 11.3 m or 26% of usual energy costs (baseline) were realised. So far, ESCOs have invested about € 49 m to refurbish different hardware components. To this objective, so-called Energy Performance Contracts (EPC) are set up between building owners and ESCOs. In average, ESCOs applying for retrofit tenders agree to realise annual savings in energy costs of 26%. To achieve this target, different hardware components such as automatic control engineering systems, heating control systems, lighting systems, ventilation and air conditioning systems can be installed. A further service is consultancy on consumer behaviour. BEA also assists building owners and ESCOs to decide on terms of repayment to ESCOs. Average payback periods are 8 to 12 years. In Berlin the first EPC contracts have expired and went for a re-tendering. With the experience of the first years EPC has developed to a sustainable and well-established model. With the realisation of successful projects and the presentation of good-practice examples EPC gains more and more attention and interest.
5. Challenges for EPC A large part of the available energy savings potential that exists today lies within buildings. A large share of this potential can be effectively realised using energy services and other energy end-use efficiency measures. It was said before that the cost effective energy savings potential in Europe is 20%. The market for energy services does not show the volume that could be expected based on the available potential. The lack of information and deficits in know-how with respect to EPC are probably the biggest challenges. Many potential customers do not know or mistrust the advantages of EPC. Energy Performance Contracting has a degree of complexity to it that asks for a well-balanced agreement between the customer and the ESCO in order to become a win-win project. It asks for both technical and economic know-how and understanding. Often, interested potential customers do not have enough experience to develop adequate tender documents and specifications in order to get a best offer, or they do not have the staff capacity to do so. The complexity of EPC is often misjudged. The integration of experienced consultants and project developers can help to avoid problems and uncertainties. The experience of some EPC projects shows that support efforts of the customer were often estimated too low. In many projects several single adjustments were necessary. This is a crucial element for the acceptance of EPC projects within the institution. In general, external support by project consultants leads to fewer efforts for the customer and a more transparent view on project tasks. Energy agencies, other experts and mediators can support the building owners in the decision process to start with project preparation for EPC or other TPF model and to give support during preparation and implementation phase. Guidelines, standards, expert events and dissemination activities will support the further market penetration of energy services and the motivation of the building owners. Connected to uncertainties, standardisation is an important element. Standards carry the potential to increase trust on all sides because they increase the procedural transparency. In addition, experience shows that tested standards do help in reducing transaction costs not only on side of the customers, but also for the ESCOs.
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The long project durations and the internal settlement (running costs vs. investment costs) play a mayor role for the initiation of an EPC project in public institutions. Especially the management level opposes contract durations of more than five years. Investments in energy saving measures are always in competition with other investments. Some customers would appreciate a more flexible model. A further aspect is the mere financial focus. Many municipalities perceive the EPC model only as a financing instrument. The measures of the ESCO that exceed the financing of installations and the optimisation of operation management – a major contractual service – are often disregarded. The energy saving guarantee is ignored by the customer assuming that self-realisation is more cost efficient. This assumption is the main reason for small and medium municipalities to decide against EPC projects. Due to bottlenecks in financing and a shortage of qualified personal an internal implementation of energy efficiency measures fails in most cases and saving targets are not met Probably the highest driver for EPC lies in increasing energy prices and the resulting need for energy efficient modernisation. EPC is a low risk and cost efficient way for the refurbishment and optimisation of energy systems in buildings. Not only energy costs but also greenhouse gas emissions can be reduced. This is an important issue with regard to climate protection targets and the role model function of the public sector.
6. Advanced EPC: possible approaches for the extension of EPC Although there are different development stages of classical EPC in Europe, especially countries with existing experiences in EPC start to develop advanced EPC to have a larger variety of the model for special customer needs. EPC plus: Many potential customers have the necessity to integrate building refurbishment measures. Within the classical EPC model measures in thermal insulation are basically excluded (too long payback periods due to high investment costs) and show the missing flexibility of the model. Buildings with a high demand for refurbishment are therefore in most cases not suitable for EPC. The reduction of heat demand of the building would lead to synergies with respect to the smaller dimensioning of technical installations (and hence less investment costs). The combination of building refurbishment and the modernisation of technical installations (EPC plus) leads to maximal energy savings and a short-term implementation of a larger package of refurbishment measures. The costs for the building refurbishment could be paid as building cost subsidy also in combination within public programs for building refurbishment. Green EPC: Beside energy efficiency the use of renewal energy sources is a main element of the EU’s climate protection package 2020. Currently just a very minor part of the measures realized by classical EPC, there is a customer need upcoming to have more REN measures realized within EPC projects. This development is also triggered by legislation such as Renewable Energy Heat Law (EEWärmeG) in Germany. Barriers to realize use of renewable energy in EPC are based on missing economic feasibility but also on missing links between existing subsidy schemes for REN use and the model EPC. Furthermore technical standards and realistic objectives for tenders have to be developed. Another target that will be considered by the development of advanced EPC is a switch from final energy consumption as main basis of the performance guarantee to a guarantee on the reduction of primary energy consumption and environmental aspects, following the idea of EPC as a climate protection instrument. EPC light: Another model containing the main feature of EPC – the performance guarantee - is to combine the operation and energy management optimization of a building with guaranteed saving targets. Within this model no or just short investments in energy efficiency measure are realized. The focus is the operation of the building following the requirements of energy saving. Another part of this model is the integration of customers for energy saving by user motivation. EPC light is an adequate follow-up
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instrument for classical EPC avoiding growing energy use after the EPC contracts duration. It may also be the right model for new buildings with no investment needs but missing personnel and knowhow for efficient energy use.
7. The EESI project and other European projects The European Energy Service Initiative (EESI) will broadly promote the implementation of EPC, thus contributing strongly to the establishment of effective energy service markets in Europe. EESI will make use of existing standards and tools for EPC and other energy services, which were developed and have been successfully tested in earlier European projects such as ClearContract and Eurocontract. Local and regional capacity-building will be achieved through national online-help desks, frequent training events for local authorities, companies, and multipliers, as well as consultancy for applying and advancing EPC-standard procedures and instruments in concrete pilot projects. The promotional campaign will imply the integration of EPC issues in national trade fairs and the high-profile annual awarding events of the “European Energy Service Award”. EESI will make a strong contribution to the further establishment and implementation of standardised EPC models in Europe. This will underline the potential of EPC as a prime instrument for the implementation of the Energy Service Directive, for the respective National Energy Efficiency Action Plans and for the further development of a European Energy Service Market. The main target groups are representatives from public sector real estates and other decision makers in local administrations with respect to communal building stock. These are representatives from the Finance Department, Authorisation Department, Planning and Housing Department, Private real estate companies, and other public building users. In accordance to the schedule of EESI, the key actors of the initiative are differentiated into three groups. The first group is composed of ESCOs, Energy Agencies, and Financial Institutions which are indispensable for an effective implementation of EPC projects. The second group of key actors are policy-makers on national and European policy level who will be addressed with regard to the policy recommendations derived from the national activities. With regard to a wider dissemination and promotion of the project results the third group of key actors are possible multipliers such as Environmental and Climate Networks, National ESCO Associations, Energy Agencies, and Energy Consultants. Expected Results - Intensive information and capacity building of local and regional decision makers for EPC - Model documents for participating countries - EPC help-desks in all partner countries - European Energy Service Award 2009, 2010, 2011 - Further development of the energy performance contracting scheme towards building envelope refurbishment - Implementation of a quality standard for EPC projects - Assistance of 24 EPC pilot projects, including 6 projects with advanced EPC standards - CO2 savings of 12,000 t per year
References [1] [2]
European Commission. Directive 2006/32/EC of the European Parliament and of the Council of 5 April 2006 on energy end-use efficiency and energy services. Official Journal of the European Union L 114/64 European Commission. Action Plan for Energy Efficiency: Realising the Potential. Communication from the Commission. Brussels, 19.10.2006. COM(2006) 545 final.
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Building Portfolio Energy Analysis – Optimization Procedure Samir E. Chidiac1, H. Lynn Perry1, Simon Foo2 and Edward Morofsky2 1 Department of Civil Engineering, McMaster University, Canada 2 Real Property Branch HQ, Public Works & Government Services Canada
Abstract Portfolio Analysis is used by owners of large stocks of buildings to carry out energy assessments on groups of buildings rather than on individual ones. Given that the number of buildings can range from hundreds to tens of thousands when national building portfolios are analyzed, the assessment provides a comparative evaluation of the energy consumption versus energy reduction possibilities on the basis of the buildings’ archetype. This approach provides useful information in a timely manner for planning, goal setting, bidding, funding or approval to proceed to more detailed analyses. Although various tools/models have been developed to analyze in detail the energy consumption of a building, including the impact of implementing energy conservation measures (ECMs), these tools are not effective when considering large stocks of buildings. A screening methodology, consisting of three stages, has been developed to conduct energy audits on office building portfolios. The first component, which is a mathematical model, provides an estimate of the energy consumption of the office buildings based on the buildings’ characteristics. The second stage employs minimization methods to determine the impact of the ECMs on the energy consumption. The third step incorporates cost analysis, which provides an estimate of the present value and payback period to determine the optimum order of selection and implementation of ECMs. The screening methodology is evaluated using five office buildings and twelve ECMs. Results obtained using the EnergyPlus model have shown that the proposed screening methodology produces energy consumption data comparative to those of the EnergyPlus model and an optimal order of ECMs to receive the best return on investment. Keywords: Office building portfolio, Energy consumption, Energy conservation measures, Payback period, Screening
Introduction Energy conservation has increasingly become a focus of the building industry as a means of mitigating the environmental impacts of energy consumption and reducing building operating costs as energy costs escalate. The application of energy conservation measures (ECMs) to existing buildings has potential to lower energy consumption while providing long-term savings to the building owner. Due to the interactive nature of building systems, assessing the impacts of ECMs on building energy consumption requires the aid of energy simulation tools. Various tools and models have been developed to estimate building energy usage and are capable of capturing the effects of ECMs, however are ineffective when considering large stocks of buildings. National building portfolios can range from hundreds to tens of thousands of buildings [1]. Obtaining the detailed information required for energy simulation programs for such a large number of buildings is tedious, time consuming, and may not be possible given the availability of information. In addition, current tools do not allow for the simultaneous analysis of multiple ECMs for multiple buildings, nor do they provide the user with a decision making tool to aid in the optimal selection of ECMs. Portfolio analysis provides owners of large stocks of buildings a means of assessing energy consumption and energy reduction possibilities for a group of buildings based on the buildings’ archetypes [1]. The portfolio analysis methodology presented herein utilizes a mathematical model to predict the energy consumption of buildings based on the buildings’ characteristics. Using variation calculus, the model can be used to determine the impact of ECMs on energy consumption and the optimal order of implementation based on energy savings. Cost analysis methods such as net present
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value and payback period can also be applied to determine the optimal order of implementation of ECMs from a financial perspective. Archetypes During preliminary planning stages not all building characteristics may be known. The use of archetypes allows for preliminary estimates of energy consumption to be made in a timely manner, which is useful for planning, goal setting, bidding, funding, or approval to proceed to more detailed analyses. Three archetypes are defined to represent building characteristics from three eras: Pre1950, 1950-1975, and Post-1975. The time periods selected coincide with significant changes in building codes/standards and changes in typical construction practices [3]. Archetype definitions include building characteristics pertaining to the building envelope, distribution system, electrical system, and natural gas system. The values for the building characteristics associated with each archetype are shown in Table 6. Table 6: Building Archetypes Characteristic Building Envelope Infiltration Rate (ach) Roof U-Values (W/m2·C) - Metal Roof U-Values (W/m2·C) - Concrete Wall U-Values (W/m2·C) - Brick Wall U-Values (W/m2·C) - Curtain-wall Window U-Values (W/m2·C) Distribution System Economizer VAV Turndown Ratio Heat Recovery HVAC and Lighting Lighting (W/m2) Daylighting Chiller COP Natural Gas System Boiler Efficiency
Pre-1950
1950 - 1975
Post 1975
1.0 1.41 1.36 1.21 n/a 6.4
0.75 0.74 0.74 1.21 0.37 3.2
0.5 0.64 0.64 1.16 0.37 2.2
No 1.0 No
No 1.0 No
Yes 0.6 Yes
26 No 1.8
17.8 No 2.5
9.267 No 5.2
0.75
0.75
0.85
Energy Conservation Measures Multiple ECMs are included in the analysis as they will affect buildings with varying characteristics differently. What is an optimal ECM for one building may not be for another. Twelve retrofits which address changes in the building envelope, HVAC and lighting systems, and natural gas system, are applied equally to all archetypes. The list of the ECMs considered is found below in Table 7. Table 7: Energy Conservation Measures ECM # ECM Description Building Envelope 1 Air Infiltration - Seal air leaks in the building envelope to reduce air infiltration 2 Roof - Install additional insulation in the roof 3 Walls - Install additional insulation in the walls 4 Windows - Install double glazed, argon-filled, low emissivity windows 5 Windows - Install triple glazed, argon-filled, low emissivity windows HVAC and Lighting 6 Air Handling Unit - Include an economizer 7 Air Handling Unit - Reduce VAV ratio 8 Air Handling Unit - Include heat recovery unit
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9 Lighting - Upgrade lighting fixtures to T8 10 Daylighting - Include daylighting sensors and shading controls 11 Chiller - Improve chiller COP Natural Gas System 12 Heating / Boiler - Improve boiler efficiency
Representative Buildings The analyses of five representative buildings in the city of Ottawa, Ontario, Canada are included to illustrate the proposed methodology. Each of the three archetypes is applied to the five buildings, excluding non-typical combinations. As curtain-wall buildings were not common prior to 1950 and it is unusual to find a high-rise building of brick construction built after 1975, these buildings have been omitted. Occupancy and building use characteristics, such as equipment loads and occupancy density, are set to reflect current day activity levels. Other common characteristics of the representative buildings include the type of distribution system (air handling unit and pumps), constant fan pressure rise, the use of centrifugal chillers, natural gas hot water boilers, and service hot water provided via electricity. Building characteristics unique to each building, presented in Table 8, include general building size parameters, building envelope type, chiller and boiler capacities, and operational schedules. Table 8: Unique Characteristics of Representative Buildings Characteristic Building 1 Building 2 Building 3 General Information Number of Floors 2 11 + 1 bsmt 11 + 2 bsmt 2 Gross Area (m ) 3,000 18,000 32,500 Gross Volume (m3) 11,250 63,750 115,000 Building Envelope Walls Brick Curtain-wall Brick Built-up Built-up Built-up Roof Metal Metal Metal Windows to Wall (%) 0.5 0.2 0.8 HVAC and Lighting Chiller Capacity 1,503 kW 8,202 kW 13,434 kW Natural Gas System Boiler Capacity 1250 kW 6,352 kW 10,402 kW Occupancy Characteristic Occupancy Schedule 5:00 - 23:00 7:00 - 17:00 5:00 - 23:00 System Setback No Setback 18° Setback No Setback
Building 4
Building 5
20 + 1 bsmt 31,500 111,000
20 + 2 bsmt 52,500 185,000
Curtain-wall Built-up Concrete 0.8
Brick Built-up Metal 0.8
14,467 kW
22,410 kW
11,136 kW
17,177 kW
5:00 - 23:00 No Setback
5:00 - 23:00 No Setback
Proposed Methodology Mathematical Model The proposed portfolio analysis is founded on a mathematical model that is used to provide estimates of the energy consumption of office buildings based on buildings’ characteristics. Without knowing the pre- and post-retrofit energy consumptions, it is impossible to quantify and verify energy savings that result from the implementation of ECMs. The model presented herein allows users to quickly and easily obtain predictions of the energy consumption of buildings and make comparisons between the energy consumption prior to and after the implementation of ECMs. A set of seven equations make up the mathematical model. They have been derived using regression analysis of energy consumption data for a variety of representative office buildings simulated using EnergyPlus software [2][3]. One equation represents each of the following building systems: boiler, chiller, domestic hot water, equipment, fans, lighting, and pumps. Natural gas consumption is found using the boiler consumption equation and total electrical consumption is the sum of the remaining energy consumption equations. The general format of the equations is shown in Equation 1.
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i 2 2 Energy Consumption ≅ • 1 (1/• * (b1*x1 + … + bn*xn + bn+1*x1 + bn+2*x1x2 + … + b2n*xn + (1) 3 2 3 b2n+1*x1 + b2n+2* x1 x2 + … + b3n*xn )) where: b = coefficients i = energy consumption component n = number of variables x = variable • = efficiency
The model uses a set of thirty-three independent variables based on general building characteristics. Variables in the model pertain to the general size of the building, building envelope, distribution systems, HVAC and lighting systems, natural gas system, and occupancy characteristics. A list of all variables is included in Table 9. To allow for the simulation of buildings at various locations, sets of coefficients have been derived for multiple cities within Canada. These cities have been chosen to represent the various climatic conditions found across the country. Table 9: Mathematical Model Variables Variable No. Above Grade Storeys Avg. Floor Area (m2) No. Below Grade Storeys Heating Setback Indicator Summer Setback Heating Temp. (°C) No. Months of Cooling per Year Occupancy Schedule per Day (hr) Occupancy Days per Week HVAC Days per Week Lighting Load (W/m2) 2 Equipment Load (W/m ) 2 Occupancy Density (m /pers) Daylighting Indicator Economizer Indicator VAV Ratio Fan Pressure Rise (Pa) Reheat Indicator
Min. Outside Air Flow Rate (m3/s) Min. Supply Fan Flow Rate (m3/s) Unitary System Indicator Heat Recovery Indicator Infiltration Rate (ACH) Roof U-Value (W/m2C) 2 Wall U-Value (W/m C) Fenestration U-Value (W/m2C) Window/Wall Ratio Max. Supply Fan Flow Rate (m3/s) Boiler Capacity (W) Chiller Capacity (W) Aspect Ratio Orientation (deg) Boiler Efficiency Chiller Coefficient of Performance
Optimization and Ranking of ECMs In order to be useful for a large portfolio of buildings, analysis of the energy consumption data generated from the mathematical model is needed. The second component of the method is a minimization procedure that uses variational calculus applied to the mathematical model equations to determine the impact of ECMs on energy consumption. This procedure is used to determine the change in energy consumption and rank the ECMs based on potential energy savings. By maximizing the energy savings, overall energy consumption is minimized. The change in energy consumption due to an ECM can be computed using a Taylor series approximation as shown in Equation 2. As the mathematical model equations are third order, using the third order Taylor Series expansion provides exact approximations of the change in energy consumption. EC(post
- EC(current) ≅ • EC(current)/• v(ECM)* • v(ECM) + • 2EC(current)/• v(ECM)2* • v(ECM)2/2! + (2) • EC(current)/• v(ECM)3* • v(ECM)3/3!
ECM) 3
72
where: EC = energy consumption v(ECM) = variable associated with the ECM Negative results indicate an energy savings while positive or zero results indicate that there is no benefit and the ECM is not applicable to the building. This calculation is performed for each ECM. Once the savings are calculated the ECMs can be ranked. The ECM with the largest energy savings will be most favorable and should be implemented first. Once an ECM has been implemented, the method is repeated in a step-wise manner using the post-ECM energy consumption as the current energy consumption to determine the second most favorable ECM. In this model, each ECM has one associated variable. The values of these variables are changed within the model to those shown in Table 10 to reflect the implementation of an ECM. Table 10: Variable Values to reflect ECMs ECM #
ECM Description
Building Envelope 1 Air Infiltration (ach) 2 Roof - Insulation (W/m2·C) (Metal) Roof - Insulation (W/m2·C) (Concrete) 3 Walls - Insulation (W/m2·C) (Brick) 2 4 Window U-Value (W/m ·C) - Double Glazed 5 Window U-Value (W/m2·C) - Triple Glazed HVAC and Lighting 6 AHU - Economizer 7 AHU - VAV ratio 8 AHU - Heat Recovery 2 9 Lighting (W/m ) 10 Daylighting 11 Chiller COP Natural Gas System 12 Boiler Efficiency
Pre-1950
ECM Values 1950 - 1975 Post 1975
0.1 0.47 0.47 0.55 2.2 1.2
0.1 0.47 0.47 0.55 2.2 1.2
0.1 0.47 0.47 0.55 2.2
Yes 0.3 Yes 5.6 Yes 6.5
Yes 0.3 Yes 5.6 Yes 6.5
5.6 Yes 6.5
0.96
0.96
0.96
0.3
Cost Analysis Although energy consumption reduction is relevant to building owners, financial implications weigh heavily in the decision making process of building management. The optimization method described above can be extended to a net present value analysis and a simple payback period analysis to determine the optimum order of selection and implementation of ECMs based on the goal of maximizing financial benefits. Although a net present value analysis is always preferred, the payback method is a commonly used indicator. The present value analysis ranks ECMs based on the net present value of costs and savings. Using Equation 3, the net present value of savings due to the ECM is calculated in current dollars taking into account: cost of energy including annual increases, cost of implementation including cost of borrowing, and change in maintenance costs [3][4]. PVsavings = Ce*• ECe*(P/A,ge,if,N) + Cg*• ECg*(P/A,gg,if,N) – CI*(A/P,iL,M)*(P/A,if,M) + • MC(P/A,if,N) where: (A/P,i,N) = Capital recovery factor: [i (1+i)N]/[(1+i)N – 1] (P/A,i,N) = Series present worth factor: [(1+i)N – 1]/[i (1+i)N]
(3)
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(P/A,g,i,N) (1+i°) ]*(1/(1+g)) ACe = ACg = CI = ƒ = ge = gg = i° = if = iL = N = M = • ECe = • ECg = • MC = N
=
Geometric growth series present worth factor: [(1+i°)N – 1]/[i°
Electricity costs ($/kWh) Natural gas costs ($/kWh) Cost of implementation Inflation rate Growth rate of electricity costs Growth rate of natural gas costs Growth adjusted interest rate: [(1+i)/(1+g) – 1] Inflation adjusted interest rate: [(1+i)/(1+ƒ) – 1] Interest rate of loan Number of years Amortization period Annual electrical savings (kWh) Annual natural gas savings (kWh) Annual maintenance cost difference (assumed constant) ($)
A common method of analysis is the payback period analysis. The payback period is defined as the number of years needed to recover the initial capital costs [4]. Equation 4 and 5 show the equations for the present value of costs and present value of savings respectively. Costs include the initial implementation cost of the ECM and the cost of borrowing. The savings include the reduction in energy consumption and the difference in annual maintenance costs. PVcosts = CI*(A/P,iL,M)*(P/A,ƒ,M)
(4)
PVsavings = Ce*• ECe(post-ECM)*(P/A,ge,if,N) + Cg*• ECg(post-ECM)*(P/A,gg,if,N) + • MC(P/A,if,N)
(5)
The number of years over which the cost is calculated is decided by the user and must be the same for each ECM to be able to make equivalent comparisons between retrofit options. Should the lifespan of the ECM be longer than the time period considered, replacement costs should also be incorporated into the equation.
Verification of Model The portfolio analysis has been performed using the representative buildings presented earlier in this paper. Select results are included below to show verification of the model. Comparisons of pre-retrofit and post-retrofit energy consumption, as well as rankings of ECMs are included. Electrical and natural gas energy consumptions using EnergyPlus and the mathematical model are shown in
Figure 15. For both types of consumption the estimates found using the mathematical model are comparable to those of EnergyPlus. It is observed that the mathematical model is capable of providing predictions for buildings of various size, construction, and archetype within an acceptable range of error such that decisions can be made as to the feasibility of ECMs and those that should be considered in further detail can be identified.
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Figure 15: Energy Consumption - EnergyPlus vs. Mathematical Model (Ottawa, Ontario, Canada)
Three ECMs have been selected to illustrate the ability of the mathematical model to predict post-ECM energy consumption results: ECM 2 (Roof Insulation), ECM 4 (Double Glazed Windows), and ECM 10 (Daylighting Controls). Figure 16 through
Figure 18 show the results of EnergyPlus simulations as well as the predicted post-ECM consumption calculated using the mathematical model. The changes in energy consumption have been added to the initial estimates to obtain the post-retrofit values. Again it is observed that the mathematical model produces results comparable to EnergyPlus for various building configurations and decisions made based on model results are consistent with those based on EnergyPlus simulation data.
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Figure 16: Post ECM 2 Energy Consumption – Additional Roof Insulation (Ottawa, Ontario, Canada)
Figure 25: Post ECM 4 Energy Consumption – Double Glazed Windows (Ottawa, Ontario, Canada)
Figure 18: Post ECM 10 Energy Consumption – Daylighting Controls (Ottawa, Ontario, Canada)
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Rankings of the ECMs based on energy savings are shown in Table 11. For the representative buildings, ECM 7 (Reduction of VAV ratio) is seen to be the retrofit that maximizes energy savings for all buildings for each archetype. Similarities in the ranking of the ECMs between buildings is also observed, however they are not identical. This illustrates the need to analyze buildings on an individual basis rather than making general assumptions as to the effectiveness of ECMs for all buildings. Table 11: Ranking of ECMs Based on Change in Energy Consumption (Ottawa, Ontario, Canada) ECM 1
2
3
4
5
6
7
8
9
10
11
12
Building 1 Building 3
3 3
10 10
9 8
5 5
4 4
12 12
1 1
11 9
8 11
7 7
2 2
6 6
Building 5 1950-1975
2
10
9
5
4
12
1
8
11
7
3
6
Building 1 Building 2 Building 3 Building 4
3 2 2 2
9 8 10 7
10
6
4
8
6
4
12 9 12 9
1 1 1 1
11 6 9 5
8 7 11 8
7 5 7 6
2 3 3 3
5 4 5 4
Building 5 Post 1975 Building 1 Building 2
2
10
9
7
4
12
1
6
11
8
3
5
2 2 2
8 7 7
9
5 4 5
7 6 6
4 3 4
6 5 3
Pre 1950
Building 4
3
1 1 1
Discussion The proposed portfolio analysis methodology provides users with a simple and efficient means of obtaining estimates of energy consumption and analysis of the results generated. A strong advantage of the mathematical model over the use of energy simulation programs such as EnergyPlus is the time needed for processing. The portfolio analysis procedure can be run within hours or even minutes. Comparing this time frame to the time needed for the same number of EnergyPlus simulations, which can be days if not weeks depending upon the complexity of the buildings, the efficiency of the mathematical model based procedure is clear. A strength of the portfolio analysis also lies in the completeness of the model and inclusion of data analysis. Energy consumption data as well as
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evaluation of ECMs is readily presented to the user in the output, eliminating the need for further evaluation of the results as is necessary with energy models such as EnergyPlus.
Conclusions The portfolio analysis methodology presented allows users to obtain information for large stocks of buildings with regards to the optimal order of implementation of ECMs that will maximize either energy or cost savings in an efficient and timely manner. Energy consumption predictions at early stages of planning are possible through use of the mathematical model and building archetypes. It is shown that the model is capable of predicting electrical and natural gas consumptions for buildings of various archetypes based on a set of variables defined by the buildings’ characteristics. In order to accurately assess energy savings resulting from ECM implementation, the model must contain sufficient detail and representation of the building systems. This is seen to be true as the model is equally capable of predicting the post-ECM energy consumption of the representative buildings similar to the results of EnergyPlus. Furthermore, the optimal order of implementation of ECMs is presented to the user through rankings based on energy saving potential. In this way, overall post-ECM energy consumption is minimized. The methodology is easily extended to maximize cost savings over a set time period of building use through adjustment of the mathematical model equations to include cost calculations. The choice of using net present value or the simple payback period analysis is dependent upon user preference. The goal of the optimization procedure is decided by the user. Should environmental effects be of primary concern, energy savings can be maximized. It is further suggested that there is potential for the optimization procedure to be extended to include minimization of green house gas emissions due to energy consumption. Pending development of a suitable equation relating GHG emissions to energy consumption of buildings, the optimization procedure can easily be adapted. This is an important note as the reduction of greenhouse gases is a target for many energy management programs. Overall, portfolio analysis is an important tool for building managers to successfully focus efforts to mitigate environmental effects of energy consumption and effectively allocate financial resources.
Acknowledgments This research was partially funded by Public Works and Government Services Canada and McMaster University Center for Effective Design of Structures.
References [1] IEA ECBCS Programme Annex 46. (2009). Energy & process assessment protocol. United States of America: International Energy Agency: Energy Conservation in Buildings and Community Systems Programme, Annex 46. [2] Lawrence Berkley National Laboratory. EnergyPlus (Version 1.4.0.025) [Software]. Available from: http://www.eere.energy.gov/buildings/energyplus/ [3] Chidiac, S. E., Catania, E. J. C., Morofsky, E., & Foo, S. (2009). A screening methodology for implementing cost effective energy retrofit measures in Canadian office buildings. Submitted to Energy and Buildings. [4] Fraser, N. M. (2000). Engineering economics in Canada (2nd ed.). Scarborough, Ont.: Prentice Hall Canada.
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Legislative Framework of Building Sector Energy Efficiency in Turkey Ebru Acuner, Sermin Onaygil, Emre Erkin Energy Planning and Management Division, Energy Institute, Istanbul Technical University
Abstract Although there exist some periods of stagnation due to economical problems, annual increase rates of energy and electric consumptions of Turkey are approximately 4-5% and 7-8%, respectively. These values are about two times greater than that the world averages. For this reason, the basic target for Turkish energy sector can be stated as sufficient, reliable and economical supply of energy demand. Among all end-use sectors, the building sector is one of the important players in Turkey, which has a share of 30% and 43% in total energy and electrical energy consumptions, respectively. For the building sector with approximately 30% energy saving potential, constitution of legal framework was started at 2007. In this scope, the first driving force is as the Law on Energy Efficiency. Afterwards, regulations on efficient utilization of energy sources and energy, building energy performance and heat sharing were published under the framework of the Law. Regulation on Building Energy Performance, prepared by Ministry of Public Works and Settlement on the basis of related EU directive, had been published in 5 December 2008 and comprises provisions on the minimum performance criteria of architectural design, mechanical, electrical as well as lighting installations and appliances that are used in the buildings, the methods of calculating energy performances and the way of preparing energy certificates of the existing or newly constructed residential, commercial and 2 governmental buildings with useful floor area of 1000 m or higher. This regulation was enforced in 5 December 2009. In this paper, it is aimed to describe the current legal situation in Turkey about the studies, such as energy audits, management systems and managers, on improvement of energy efficiency in the building sector, especially considering commercial ones, as well as to give some recommendations for the future studies in Turkey by considering not only the successful implementations but also problems that were faced during the implementations in other similar countries.
Introduction Within the last 35-40 years, energy efficiency has become more important due to fast degradation of fossil fuels as a primary energy source, difficulties in both the control of increasing energy prices and supplying sustainable energy as well as increase in the dependence on imported energy sources. Energy efficiency can be defined as a decrease in the energy used for producing either a product or a service without reducing the quality and the performance. In whole over the world, it is accepted that energy saving achieved consequently after the efficient usage is stated the cheapest energy source. Moreover, energy efficiency has a strategic importance to mitigate compulsion of energy costs on the economy as well as adverse impacts of energy consumption on the environment. In order to continue her development, Turkey needs energy. Although there have been several periods of stagnation due to economical problems, Turkish energy demand and consumption experience an increase in the rate. Annual increase rates of energy and electric consumption in Turkey are approximately 4-5% and 7-8%, respectively. These values are about two times greater than that the world averages. Moreover, in Turkey, it is stated that about 500 $ is spent on energy imports per capita [1]. For this reason, the basic target for Turkish energy sector, having limited possibilities considering energy sources, is a sufficient, reliable and economical supply of energy and from this point of view, energy efficiency can be stated as a one of the main instruments in energy production, transmission, distribution and consumption. In case of consumption, among all end-use sectors (industry, building, transportation), the building sector is one of the important players in Turkey, which has a share of 30% and 43% in total energy and electrical energy consumptions, respectively [2].
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The industrialization and welfare of any country has a strong relationship with not only energy consumption but also using energy efficiently. In Turkey, studies for the industry sector regarding energy efficiency have been conducted since 1980s. On the other hand, for the building sector with approximately 30% energy saving potential [3], studies started after the constitution of legal framework at 2007. In this scope, the first driving force can be stated as the Law on Energy Efficiency (hereafter EVK). Afterwards, regulations on efficient utilization of energy sources and energy, building energy performance and heat sharing were published under the framework of the Law. In this paper, it is aimed to describe the current legal situation about the studies, such as energy audits, management systems and managers, on improvement of energy efficiency in the building sector, concerning commercial ones, on the basis of implementations stated in these regulations as well as to give some recommendations for the future studies.
Energy Efficiency in Building Sector In this section, current legislative framework and proposed implementations on energy efficiency with regard to the building sector are explained. Current legislative framework Figure 1 represents up-to-date regulations and standards related to the building sector within the framework of EVK with their enforcement dates. Figure 1. Current legislative framework on energy efficiency in Turkish building sector
EVK was enforced on 2 May 2007 (Official Journal Number: 26510).The fundamental aims of the Law are to use energy and its main sources efficiently, to reduce energy losses, as well as its costs that affect the national economy adversely and to protect the environment. Considering these aims, the scope of the Law comprises energy efficiency related activities and implementations for energy production, transmission, distribution and consumption sectors [4]. Previously, energy efficiency activities which concern especially end-use sectors were conducted by only the General Directorate of Energy Sources Survey and Development Administration (EIE) under the supervision of the Ministry of Energy and Natural Resources (MENR). After EVK, in order to conduct such activities the new administrative structure has been constructed (Figure 2).
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Figure 2. New administrative structure related to energy efficiency after EVK in Turkey
In this new administrative structure, the authorization with regard to organizing energy manager courses can be given to both universities and specified chambers of engineers (hereafter authorized institutions) by EIE, which acts as a secretariat under the supervision of Energy Efficiency Coordination Board (EECB). In addition, either EIE or authorized institutions can give authorizations related to training, auditing, consulting and implementation activities to energy service companies (ESCOs) and these institutions should provide required laboratory infrastructure especially for the trainings, which will be organized by ESCOs [4]. In order to explain energy efficiency activities and implementations regarding the building sector, which will be conducted on the basis of this new administrative structure, the prepared regulations are listed below in the order of their enforcement dates: • • •
Regulation on Sharing the Expenses of Centralized Heating and Hot Water, Regulation on Efficient Utilization of Energy Sources and Energy, Regulation on Building Energy Performance.
Regulation on “Sharing the Expenses of Centralized Heating and Hot Water” (hereafter heat sharing), which is the first regulation, prepared after the Law, was published on 14 April 2008 (Official Journal Number: 26847). The aim of this regulation is to state provisions and implementations considering the share of heating and hot water expenses among the independent consumers in the existing or newly constructed buildings with centralized or regional heating and hot water facilities. In this scope, the main implementation is the installation and usage of thermostatic radiator valves. The related standard, namely TS EN 215, prepared in 2007, should be taken into consideration for the proper implementations [5]. In line with the aim of EVK, regulation on “Efficient Utilization of Energy Sources and Energy” (in Turkish the short name is En-Ver), published on 25 October 2008 (Official Journal Number: 27035), comprises provisions and implementations for efficient usage of energy in not only end-use sectors (industry, building, transportation) but also production, transmission and distribution sectors to prevent waste of energy, to reduce the adverse impacts of energy costs on the national economy and to protect the environment [6]. For detail explanations of implementations, the Notice entitled “Provisions and Principals Regarding Authorization, Certification, Reporting and Project Development on the basis of EVK” was published on 6 February 2009 (Official Journal Number: 27133) [7].
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The last but not the least regulation namely “Building Energy Performance” (hereafter BEP) was enforced on 5 December 2008 (Official Journal Number: 27075). The major aims of BEP are as follows: • • • • • • •
to state the calculation procedures for the evaluation of energy consumption of any building considering outside weather, inside comfort and all local conditions as well as cost effectiveness, to determine the energy consumption and CO2 emission classes of the building, to set minimum energy performance requirements for the existing buildings that will be renovated, to evaluate the possible applications of renewable energy sources to meet the energy requirements of the buildings, to control both heating, cooling, ventilation, lighting and electrical systems, to put restriction on the green house gas emissions, to decide the energy related performance criteria for the buildings [8].
Under the framework of BEP, the main standards that were prepared can be listed as “TS 825 Building Heat Insulation” (revised in 2008), “TS 378 Cooling Systems and Heat Pumps” (chain standards between 2001 and 2007), “TS EN 14336 Heating Systems: The establishment and operation of water based heating systems for buildings” (2007), “TS EN 832 Thermal Performance of Buildings: Calculation of energy required for heating purposes in the houses” (2007) and “TS EN 15193 Building Energy Performance: Energy requirements for lighting” (2008). All other related standards with their conjugate European ones are mentioned in BEP and it is stated that if there exists any requirement, the original European standards can be used for the implementation. In addition, in BEP it is pointed out that the performance calculation procedures for the energy systems of the buildings should be prepared until 5 December 2009 and for this reason, related studies regarding building energy performance calculation were already finished and the certification of the buildings shall be started in July 2010. Implementations under related regulations In this section, implementations concerning specifically the commercial buildings were summarized and explained on the basis of En-Ver and BEP regulations. En-Ver Regulation En-Ver was prepared by EIE. The scope of this regulation comprises detail information, of which the framework was explained in EVK, about authorization of universities, chambers of engineers (mainly mechanical and electrical) and ESCOs in order to spread the energy efficiency related activities to all over the country, energy management implementations, energy managers with their responsibilities, energy efficiency audits and incentives regarding energy efficiency projects for all end-use sectors. Considering this wide-range scope, the implementations as well as responsibilities of shareholders in the building sector are summarized in Table 1. As can be seen from the Table 1, the buildings owners that are obliged to authorize energy managers must send the name(s) of the energy manager(s) to EIE until May 2009. Unfortunately this process cannot be completed. Furthermore, energy consumption information, requested by EIE from these types of buildings, must be reported by March every year. Table 1. Provisions for Turkish building sector stated in En-Ver
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1. Assignments of energy managers:
Implementations
a) Commercial and service buildings having either 20 000 m2 or more construction area or 500 ton oil equivalent (toe) or more total energy consumption annually and governmental buildings with either 10 000 m2 or more construction area or 250 ton oil equivalent (toe) or more total energy consumption annually are responsible. b) The time period for authorization energy managers by building owners or administrative body: - For existing buildings by 2 May 2009, - For buildings that will be newly constructed within 90 days after obtaining the building usage permission license. c) Required educational background to be an energy manager: - Person with mechanical, electrical or electrical/electronical engineering degree or mechanical or electrical technicians from technical education faculties, - Member of related chamber in case of being an engineer. 2. Energy Audits and Projects for increasing efficiency: - Performing energy efficiency audits in terms of heat insulation, heating, cooling, hot water and lighting systems within 3 years after enforcement of this regulation, - Preparing projects that are for implementation of the determined measures after the audits.
Responsibilities
Reporting all energy related consumption information to EIE by the end of March every year.
In addition, in order to increase energy efficiency in the governmental buildings, the major measures considering thermal, electrical and general energy usage, stated in En-Ver, is as follows: (1) Usage of thermal energy; a) Within the winter; the indoor temperatures should be arranged in such a way that it does not exceed 22 oC. b) When buying new buildings, air conditioners with A or higher energy classes should be preferred. o Cooling systems should not be used if the outside temperatures are below 30 C and they should be o adjusted that the inside temperature should not be below 24 C. c) Heat insulation plates should be placed behind the radiators and to prevent heat losses the above and front sides of them should be kept open. d) Windows insulation should be utilized to prevent the air leakages. e) Before every winter period, the regular inspections of the heating systems including proper calibration of burner settings on the basis of flue gas measurements should be performed. (2) Usage of electrical energy; a) In case of lighting, compact fluorescent lamps and high efficiency fluorescent lamps with electronic ballasts or light-emitting diodes (LEDs) should be used instead of incandescent lamps and fluorescent lamps with magnetic ballasts, respectively. b) Control systems with thermal, movement and light sensors should be used in the rooms which are rarely used. c) To achieve more efficiency, the luminaires that have reflectors with high reflection factors should be used instead of the form that does not let all light pass through it. d) In the indoor lightings, within the building section having more than one luminaire, for each of them or for the parts obtaining daylight, the proper grouping should be arranged and manual or automatically daylight control systems should be utilized. e) Computers, printers, photocopy machines and all similar electrical appliances should be selected among the ones with “Energy Star” labels and/or with minimum efficiency criteria that comply with the related standards. (3) General energy usage:
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a) Control and optimization of burning, recovery of waste heat, returning condensate, insulation of heat transfer surfaces and reduction of blow-off losses should be conducted within the boilers. b) Piping systems and valves should be insulated in heat energy distribution systems and they should be checked regularly. Also, heat should be distributed by adjusting the minimum values of pressure and temperature within the piping system. Steam traps that exist in the distribution system should be inspected regularly. c) Heating batteries should be kept clean in the ventilation systems and unwanted air leakages should be reduced. BEP Regulation This regulation, prepared by MoPS, comprises provisions on the minimum performance criteria of architectural design, mechanical, electrical as well as lighting installations and appliances that are used in buildings, the methods of calculating energy performances and the way of preparing energy certificates of the existing or newly constructed residential, commercial and governmental buildings with 1000 m2 or higher usage area. Table 2 represents the main implementations stated in BEP. The responsible bodies are defined as the institutions with the authorization of preparing energy certificate, investment companies, owners or managers or energy managers of the building, employers or their representatives, architects or engineers in charge of the design, consultants or projects controllers that works in the construction and usage of the building and inspection companies according to the type of the buildings. Table 2. Provisions for Turkish building sector stated in BEP regulation
Architectural project design and implementations
Heat insulation, minimum air circulation and leak proofing
(1) Project design: a) Prevention of unwanted heat gains and losses on the basis of meteorological conditions by means of architectural measures, b) Designing in such a way that living areas can have a chance to get maximum sun light as well as heat so that natural ventilation can be the utilized, c) Evaluating alternative design opportunities for using renewables, if possible. (2) Implementations: a) Using TS 825 standard for determining heat transmission coefficients of all external surfaces that loose heat, b) Using thermal and sun controlled glasses in the buildings that have mechanical air conditioning to prevent unwanted heat gains. (1) Determining heat insulation principles according to TS 825 standard, (2) Calculating heat losses due to thermal bridges on the basis of TS EN ISO 10211-1, TS EN ISO 10211-2, TS EN ISO 14683 or TS EN ISO 6946 standards and using these values in annual heat requirement calculation, (3) Requesting “heat insulation project” together with “installation projects” before issuing the license, (4) Insulating all mechanical installations that will be used in the heating, cooling and ventilation systems by proper insulation materials, (5) Proper materials for leak proofing in the places through which air circulation can be used.
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Heating systems
and
cooling
Ventilation and air conditioning systems
Hot water production and distribution systems
Automatic control
Electrical installations and lighting systems
Energy certificate
1) Performing design calculations for heating systems by means of TS 2164, (2) Preferring central heating in new buildings if they have 1 000 m2 or bigger usage area, (3) Using heating system with condensation in central heating as well as individual systems with 250 m2 or more usage area, (4) Using control devices for arranging inside temperature on the basis of outside one in central heating systems, (5) Selecting pumps with pressure, flow rate or time based inverter control, (6) Using calorimeters or heat meters for sharing of expenses among the consumers properly in the central heating systems, (7) Designing central cooling systems for commercial and service buildings with 500 kw or greater cooling requirement and/or 2000 m2 or more total usage area, (8) Selecting cooling fluid on the basis of TS EN 378, (9) Performing periodical inspections of heating and cooling systems, (10) Improving or replacing boilers older than 15 or 20 years for the ones using solid fuel or liquid/gas fuel, respectively, (11) Improving or replacing cooling systems older than 20 years. (1) Designing ventilation and air conditioning systems on the basis of TS 3419 and also related EU standards, (2) Determining criteria for improvement of energy performances and comfort conditions by means of EN 7730 and TS 2164, (3) Determining heat transmission coefficient of air conditioning systems according to EN 1886, (4) Following the rules stated in TS 5895 for the operation and maintenance of ventilation and air conditioning systems, (5) Following the rules in TS 3420 as well as related EU standards for placing these systems. (1)Calculating annual energy requirement of hot water systems on the basis of prEN 15316-1 which is under preparation, (1)Designing central hot water systems for hotels, hospitals, dormitories and sport centers with 1 000 m2 or more usage area, (3) Calculating the thermal performance of individual and central hot water systems according to TS EN 26 and TS EN 89, respectively. (1) Using automatic control systems for heating, cooling, ventilation systems considering specified values of these systems, if any, (2) Controlling lighting systems in all types of buildings except residential ones by time, daylight or usage based control systems, (3) Constructing energy monitoring systems in new buildings so that measurement of individual energy consumptions of lighting, heating, cooling and air conditioning systems by the help of energy analyzers. (1) Calculating the share of lighting system energy usage by using the method stated in EN 15193, (2) Avoiding unnecessary artificial lighting to get maximum benefit from the daylight, (3) Preferring tubular fluorescent lamps with electronic ballasts, compact fluorescent and sodium vapor lamps. (1) Preparing energy certificate which will be valid for 10 years according to EN 15217, (2) Requesting “energy certificate” for all new buildings in all selling and renting procedures, (3) Preparing energy efficiency coefficient of all related systems as an annex to calculate building energy performance value.
Within the framework of BEP, energy certificate must be prepared for both existing and newly constructed buildings and it shall be valid for 10 years. On the other hand, within first 3 years all
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related measurement and calculations required for energy certification will be performed again in order to check the energy and environmental state of the building and afterwards, every 2 years, regular inspections shall be conducted. This means that if it is considered necessary, energy certificate will not be valid for 10 years; hence the new certificate should be issued after applying measures, determined by these regular inspections. Moreover according to BEP, non fossil-fuel energy systems using renewable energy sources, such as hydraulic, wind, sun, geothermal, biomass, biogas, waves should be considered as an alternative solutions for heating, cooling, air conditioning, hot water, electrical and lighting energy systems within the buildings. Also it is mentioned in BEP that the Ministry of Public Works and Settlement shall prepare notification for heating and cooling annual energy requirements. For lighting and hot water energy requirements, TS standards that are issued by Turkish Standard Institute (TSI) shall be taken as a guide. If they are not issued, related EU standards for lighting and hot water energy requirements shall be used. The total annual energy requirements of any building can be calculated by adding heating, cooling, lighting and hot water requirements. In the annexes of BEP; minimum insulation thickness of heating and hot water installations, the proper light sources for lighting systems, the structure of energy certificate, reference values and emission coefficients related to primary energy and greenhouse gases depending on heating regions that are determined within Turkey, energy classes on the basis of primary energy consumptions, heat insulation details and all relevant Turkish and EU standards are explained. On the other hand, Turkish standards require some improvements as far as new technological developments are concerned in these fields. In addition to these required revisions, studies with regard to building energy performance calculation procedures are carried on under the supervision of the Ministry of Public Works and Settlement.
Conclusion and Recommendation The primary concerns for Turkish building sector that has second place after industry sector conceiving total energy consumption are stated below: • • • • •
for existing buildings, renovating or replacing old heating and cooling systems with the new ones and also changing the lighting system appliances with more efficient and technological ones, besides commercial and service sector buildings, giving primary attention to governmental ones which are in very poor conditions in terms of energy performances , with appropriate appliances and system designs usage of energy efficiently, especially for heating and cooling system, preferring central applications, if possible, evaluation of domestic and renewable energy sources possibilities.
For the existing buildings, all aforementioned regulations will be compulsory within the period of 10 years after the enforcement of EVK. This period may seem to rather long as compared to other countries. On the other hand, Turkey is a very wide country having different climatic conditions and there are various types of buildings and construction methods. In other words, right now, already two years passed. If it is figured out that only in Istanbul, which is the most crowded city in Turkey, approximately 65% of the buildings does not have any construction license, this transition period seems appropriate. Since the energy consumption for the heating systems of the buildings is two or three times greater than the EU buildings, the priority has been given to these systems as well as the insulation subject in Turkish legislation [9]. On the other hand, due to climate change issue, the load of cooling systems has been increasing and this creates negative impacts on electric networks. For this reason, the required legislative arrangements are started to be prepared by EU. In parallel to this progress, Turkey should follow this new legislation and prepare its own regulation considering national conditions, as well. It is very obvious that related regulations and standards on electrical installations and lighting systems should also be prepared on the basis of unit cost increase in electrical energy prices and the import dependence. In addition, adverse impacts of power factor values and harmonics, created by the electrical appliances that are used in the buildings should be taken into consideration in terms of energy quality.
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As mentioned before, annexes of BEP regulation comprise technical details regarding system installations, proper appliances that will be utilized for efficiency improvements (i.e lamps, luminaries, etc.) and reference values, required to calculate energy consumption and CO2 emission classes of the building. However, these are not satisfactory enough; hence, they should be revised according to the new technological improvements. In BEP, it is explained that energy certificate classification system will be issued for whole building including all the systems. On the other hand, in order to specify the conditions and problems, if any, for each energy consuming system, separate classifications should be considered. All energy consuming systems within any building may have an effect on each other. For example, wrong usage of light sources causes an increase in the load on cooling systems. Hence, it is always thought that these systems should be considered together. As can be understood from the abovementioned remarks, although energy efficiency studies for building sector was started at 2007, this can be evaluated as an advantage since Turkey has a chance to do benchmarking concerning the best practices in EU member states having similar national conditions with regard to energy, economical, technical, environmental and social issues. This point is very crucial especially for the successful implementation of the building energy performance calculation methodology to realize huge energy saving potential in building sector. For instance in Turkey, when the electrical energy consumption ratios are investigated between1992-2008, it can be observed that the share of commercial buildings reaches up to 14.8% in 2008 from 6.1% in 1992 [10] and it can be estimated that the total number of commercial buildings is approximately 1200000 [11]. Because of the variety and complexity of energy systems within these buildings, the requirement of interdisciplinary studies and the intersection of responsibilities of related governmental institutions, there exists a need for very broad organizational structure. Up to now, eleven companies are authorized by EIE as an ESCO for organizing energy manager courses and conducting energy audits in the building sector. In addition, energy certification of these buildings shall be started in July 2010 and the potential institutions or companies, such as ESCOs, which are willing to prepare these certificates should be selected carefully as well as educated well mainly considering the proper formation of the ESCO market, which can be stated as a tool for wide spreading the energy efficiency studies in the country, and energy audits which are crucial for ESCOs to determine real energy saving potentials in such buildings. Only by this way, 30% energy saving potential in this sector shall be realized for Turkey.
References [1]
MENR. Ministry of Energy and Natural Resources. Energy Statistics 2007.Can be downloaded from: www.enerji.gov.tr/EKLENTI_VIEW/index.php/raporlar/detayGoster/40863.
[2]
Kilic N. Report on Efficient Utilization of Energy Sources and Energy Regulation. Chamber of Izmir Trade. Research and Development Journal. (Izmir, December 2008).
[3]
EIE.General Directorate of General Directorate of Energy Sources Survey and Development Administration. Energy Efficiency Legislation and Implementations. Energy Efficiency and Quality Symposium. Chambers of Electrical Engineers. (Kocaeli, 21-22 May 2009).
[4]
EIE. General Directorate of Energy Sources Survey and Development Administration. Law on Energy Efficiency. (Ankara, 2007). Can be downloaded from: www.eie.gov.tr/duyurular/EV/EV_kanunu/EnVerKanunu_Temmuz2008.pdf.
[5]
MoPS. Ministry of Public Works and Settlement. Regulation on Sharing the Expenses of Centralized Heating and Hot Water. (Ankara, 2008). Can be downloaded from: www.mevzuat.adalet.gov.tr/html/27881.html.
[6]
EIE. General Directorate of Energy Sources Survey and Development Administration. Regulation on Efficient Utilization of Energy Sources and Energy. (Ankara, 2008). Can be downloaded from: www.eie.gov.tr/duyurular/EV/EV_kanunu/EV_yonetmelik/EV_yonetmelik.html.
[7]
EIE. General Directorate of Energy Sources Survey and Development Administration. Notice on Provisions and Principals Regarding Authorization, Certification, Reporting and Project
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Development on the basis of EVK. (Ankara, 2009).Can www.eie.gov.tr/duyurular/EV/EV_kanunu-teblig_200901.html.
be
downloaded
from:
[8]
MoP. Ministry of Public Works and Settlement. Regulation on Building Energy Performance, (Ankara, 2008). Can be downloaded from: www.binaisletimi.com/2008/12/binalarda-enerjiperformansi-yonetmeligi.
[9]
MoPS. Ministry of Public Works and Settlement. Regulations Related with Building Sector in Turkey. DG of Construction Works together with Association of Construction Materials Manufacturers. (Ankara, 2009). Can be ordered from: www.imsad.org.
[10]
TEDAS. Turkish Electric Distribution Company. Turkish Electric Distribution and Consumption Statistics 2008. Can be downloaded from: www.tedas.gov.tr
[11]
Cornut B. Key figures on buildings 2007. Can be downloaded from: www.eie.gov.tr/turkce/en_tasarrufu/uetm/twinning/sunular/bina_11temmuz
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IEECB'10 - Barriers, Financing & Risk Analysis
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A Framework for Estimating and Communicating the Financial Performance of Energy Efficiency Improvements in Existing Commercial Buildings While Considering Risk and Uncertainty Alireza Bozorgi, MArch, MSc Ph.D. Candidate in Design Research | MBA College of Architecture and Urban Studies | Pamplin College of Business Virginia Polytechnic Institute and State University James R. Jones, Ph.D. Associate Professor of Architecture College of Architecture and Urban Studies Virginia Polytechnic Institute and State University
Abstract There is substantial evidence suggesting that property professionals, such as owners, investors and lenders who are involved in the investment decision-making process are increasingly interested in energy efficiency improvements (EEIs). One of the primary barriers to EEI is a lack of clear information regarding the true value, both revenue and risk, of EEI investments. EEI investments often include many non-quantifiable benefits as well as risks that current energy performance assessment tools and methods do not simultaneously incorporate. Nor are the outcomes typically presented in appropriate terms to be understood and utilized in the investment decision-making process. In this paper, an analytical method and systematic framework is proposed to evaluate the financial performance of EEI alternatives in existing commercial buildings, while simultaneously addressing the risks and uncertainties associated with the process. The framework is a robust valuation process that takes EEI alternatives, uses current energy simulation programs to forecast estimates of the energy efficiency outcomes, links the predicted building performance to financial model inputs, and derives ranges/distributions of their bottom line financial performances. A Monte Carlo simulation model, based on the Discounted Cash Flow approach, is suggested for modeling the uncertainties of valuation process and estimating the financial performance. It is the objective of this study to create a single platform to bridge the gap between the design and investment communities and translate the technical language to financial language in order to present more reliable and understandable information regarding EEI’s return on investment and its associated risk and uncertainty.
Introduction With rising energy costs, climate change and global warming, property professionals, such as owners, investors, real estate developers, asset managers, lenders and bankers who are involved in the investment decision-making process have become more interested in investing and financing energy efficiency. The property industry is now mature enough that portfolio and asset managers understand the economic and marketing benefits of improving energy efficiency across their portfolio of real estate. Historically, investor-owners have less of an incentive to invest in improvement for their properties rather than owner-occupiers who tend to have a longer outlook on their real estate holdings. Investor-owners have until recently received little or no additional monetary reward for the improvements incurred from the marketplace [1]. Today, investors-owners have found that sustainability is a necessary and appropriate defensive strategy for preserving occupancy, particularly for owners of older office buildings and shopping centers most at risk of losing tenants to newer, greener buildings coming into the market [2]. Improvement or green retrofits today are recognized as excellent investment opportunities among the investors and owners of existing property. The recent shift towards achieving LEED for Existing Building Certification among the investor-owners proves their increased awareness of potential returns inherent in improvement investment.
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However, despite the increased general awareness of property professionals of positive financial performance and prediction of future growing demand, the magnitude of EEI investment is much lower than what it was expected to be. Real estate investors, owners, and managers still do not feel confident in investing and selecting the EEI alternatives. Essentially, these professionals need to ensure that their investment will generate a reasonable and competitive rate of return in the market with the lowest possible risk; they need to know if the risks associated with their investment are adequately compensated by expected returns generated. The authors believe that the process of investment decision making for selection of EEI for major retrofits is not different from typical property investment decision making from the perspective of risk and revenue. Thus, real estate professionals need to thoroughly recognize the market value, both revenue and risk, added by EEI in their financial analysis. There is also a significant amount of uncertainty associated with achieving the expected outcomes in EEI investment that needs to be explicitly taken into account in the investment decision making process. Simultaneous consideration of potential revenues, risks and uncertainties, which factor in the full scope of costs and benefits of EEI, will enable final decision makers to understand true financial performance of EEI, make more informed decisions about investing in energy efficiency and select the best possible EEI alternatives for major retrofitting of their existing building. The existing tools and techniques primarily used by design professionals do not suffice in providing final decision makers with the comprehensive and reliable financial information they need for their investment decision making process. Accordingly, there is a need to explicitly connect building performance estimates from the design professionals to the more sophisticated financial tools used by property professionals to measure the financial impact of EEI alternatives and represent them in a language that can be understood and utilized in the investment decision making process. This is the deficiency that we aim to address throughout this paper.
Existing Energy Tools Used for Evaluating EEI In the last two decades, design professionals such as architects, engineers, construction consultants, and facility managers have been widely using building energy simulation programs, not only in designing and planning a new building but also in evaluating the energy performance of an existing building. These technical tools primarily provide users with forecasts of the impacts of design decisions on energy performance indicators such as electricity or gas usage. Some of them also perform simple financial evaluations primarily based on simple payback and simple return on investment approaches. They take the building systems and strategies as inputs, and evaluate and project the building performance or simple financial performance as outputs. Currently, many minor and major retrofitting decisions are made based on the outcomes of these tools. The models help decision makers explore the potential energy saving by each EEI alternative, compare them, and select the most effective options. However, there are two major problems with using energy simulation programs for making major EEI investment decisions: 1) Communication between Technical and Financial Decision Makers: these technical tools have been primarily designed to model and analyze the energy performance indicators of interactive energy related systems and their outcomes are described in technical language. Therefore, due to their technical outcomes rather than financial outcomes, these tools are not able to communicate the overall energy performance to the investment decision makers in the way they can understand and directly utilize in their investment decision making process. Although many of the financial performances are the result of non-financial factors of the EEI alternatives employed in the buildings, investors are more concerned with the final performance in financial language and not as much with the technical details associated with the building performance outcomes. Most of the current tools are well developed to deal with the complexity and dynamic interactions of building systems performance in evaluating the energy performance, but fail to properly link energy to financial performance and do not translate the technical language to financial language. 2) Simplistic Financial Analysis: the financial analyses that some of these tools perform are based on the initial cost and operational cost saving. Simple financial techniques, such as Simple Payback (PB), Simple Return on Investment (ROI) and Life Cycle Analysis (LCC), are utilized as the primary methods in these analyses. Traditionally, due to their simplicity, these types of financial techniques are used very often by decision makers for assessing the energy efficiency investment and selecting the best EEI alternative. However, they ignore many costs, benefits, and positive and negative risks of 92
energy efficiency investment, as well as uncertainties associated with the process of achieving those benefits. The full costs and benefits of energy efficiency are beyond the operational cost saving and traditional financial analysis; and ignoring them, may undervalue the investments and exclude many profitable investment opportunities from consideration, which ultimately would lead to underinvestment in EEI. For example, investment in energy efficiency in a non-green office building will decrease energy cost but at the same time may increase the benefits such as access to incentives, improve worker health and productivity, reduce electricity consumption volatility, achieving energy certification, etc. The available incentives may pay for a significant portion of the investment costs and therefore should be considered in the investment analysis. Improved worker health and productivity in an office building may contribute to the significant cost savings for employers because of lower absenteeism and recruiting costs, and also increase the ability to meet evolving tenant demand, which would lead to lower turnover rate. Reducing electricity consumption volatility would reduce the risk of budgeting and cash flow management by increasing the predictability of energy consumption. Achieving energy certification, such as EnergyStar, or contributing to achieving sustainability certification, such as LEED, would increase the reputation and marketability of the subject building, which would lead to higher absorption rates. These are examples of the types of benefits that are ignored when making investment decision solely based on the results of energy simulation programs. Accordingly, the current energy assessment tools do not simultaneously incorporate all of the costs, benefits, risks and uncertainties of EEI investment, nor represent them in appropriate terms to be understood and utilized in the investment decision-making process. None of them on their own are sufficient to rely upon for making high-quality investment decisions for major EEI [5]. Relying solely on their simulation results often undervalue the energy efficiency and therefore, many EEI profitable opportunities may be excluded from investment consideration. Below is list of some of the potential energy efficiency benefits that might impact the property market value after EEI, true return on investment of EEI, and ultimately EEI investment decisions [6]. They are typically ignored in current energy assessment models: • • • • • • • • • •
Access to utility incentives, state agency incentives or federal government incentives; Tax saving benefits; Insurance saving benefits; Better financing options; Expedited Permits benefits; Reduce the carbon emission; Contributing to achieving sustainability or energy certification, such as LEED or EnergyStar; Improve worker health and productivity; Increase property reputation and marketability; and Increase asset value or revenue due to improved appeal to regulators, space users and investors, which would lead to higher rent, higher occupancy, lower turnover rate, higher absorption rate, etc.
Some of the potential positive risks include: • • • • • • • •
Reduce the risk of losing value due to functional obsolesce; Reduce the risk of losing tenants due to availability of energy efficient buildings in the future markets; Reduce the risk of inaccuracy of projected building performance [7]; Reduce the risk of energy price volatility; Reduce electricity consumption volatility; Reduce the risk of budgeting and cash flow management by increasing the predictability of energy consumption; Reduced liquidity risk; and Reduced legislative risk.
Some of the uncertainties inherent in the EEI valuation process include: 93
• • • • • • •
Uncertainty associated with forecasting energy performance by energy simulation tools; Uncertainty associated with achieving any certification or energy label; Uncertainty associated with improving health and productivity; Uncertainty associated with achieving the expected rents, occupancy, etc. Uncertainty associated with future cost of oil or energy price; Uncertainty associated with future interest rates and inflation rate; and Uncertainty associated with future utility rates.
Energy Performance Evaluation Many valuation experts have argued that evaluating the actual building performance is the best way to determine the financial performance of a property. The actual building performance can be understood by looking at the utility bills such as electricity or water. The problem with this approach is that in new construction or major retrofits the investment decisions need to be made when measuring the actual performance is not possible, when the building systems are not yet installed and operation data are not available. In these situations the energy simulation software tools we discussed previously are the forecasting tools for the building performance. Evidence shows that actual energy performance may differ from what was forecasted by energy simulation models such as e-Quest or Energy-Plus. Energy forecasting models, while generally considered fairly accurate, are subject to some level of intrinsic error ranging from 10% to 20% or more [8]. Therefore, there is always a certain amount of uncertainty associated with projecting the energy use based on design assumptions. It is critical for decision makers to consider the inaccuracy/error of modeling forecasts to avoid overestimating or underestimating the building performance when making decisions based on the actual performance. In this paper, we suggest introducing ranges and distributions for reporting the building performance outcomes with the mean of modeled forecasts in order to incorporate the risks inherent in modeling projections. Another important issue in evaluating the outcomes of energy efficiency systems is that most of the energy-related systems and strategies, which are typically employed in retrofitting existing buildings, have more benefits than just lowering energy consumption. For example: employing a new energy efficient HVAC system may reduce the energy consumption but at the same time may improve the ventilation rate, reduce the air pollution, reduce the noise level and therefore, improve indoor environmental quality. Also, they might have opposite results. For example, utilizing an insulating strategy may perform well for energy efficiency but badly for moisture. Implementing a bad daylighting strategy may improve the energy efficiency but increase glare and thereby, lower the user’s satisfaction. Unfortunately, today most of the energy efficiency evaluations are based on the simulation of energy-related systems in a single energy simulation program, such as DOE 2, and therefore, their other potential impacts on performance, such as indoor air quality, thermal comfort, vision performance, acoustic performance, etc. are ignored. Thus, energy-related systems’ and strategies’ contribution to performance are beyond the direct energy cost savings, they do impact on other building performance mandates. Later, we have explained that these indirect-impacts on building performance or “non energy cost saving” could play a direct role in the financial performance of a building and therefore, are important to be considered in performance valuation. Depending on the level of the accuracy and sophistication of energy performance valuation that is required by final decision makers, energy consultants could do the followings: Model the EEI with a energy simulation program, do research from available data and studies about other potential costsbenefits of that EEI and adjust their finding for their specific buildings. Or, they could model an EEI with multiple Building Simulation Programs (BSPs) to understand the range of impacts on other performance mandates. BPSs, which are widely used by design professionals to model and analyze building performance outcomes, are capable of dealing with the complexity and dynamic interactions of building performance. Each program has advantages and disadvantages in evaluating the specific indicators. A BPS might be a great tool for predicting the monthly energy consumption, but a poor estimator of building ventilation. For example, DOE-2 is widely used in the U.S. for calculating energy consumption, and CFD tools are generally accepted for the study of building ventilation, indoor air quality, or thermal comfort. To date, no program has been developed to evaluate all the performance indicators simultaneously. “It is a common fact nowadays that for any given problem there is usually more than one BSP that can meet the requirements.” [9]. Due to the costs of software and modeling personnel, users usually model a building with a single simulation tool, and judge the building 94
performance based on the results of this tool. In some cases, this would lead decision makers to make poor decisions. Therefore, for a thorough energy efficiency valuation we encourage users to model an EEI with more than one simulation program.
The Financial Model for EEI Valuation: Discounted Cash Flow Approach One of the most common and powerful financial models currently used and widely accepted in real estate as the basis for investment decision making is the Discounted Cash Flow method (DCF). The DCF technique evaluates the present value of the projected future cash inflow and outflow over the holding period (generally a term of ten years for commercial office buildings). DCF inputs include rent, occupancy, operation costs, tax and capital costs, absorption rate, depreciation, holding period, discount and capitalization rate, etc. The DCF model makes explicit the assumptions on model inputs, projects the revenue over the holding period, and estimates the financial performance indicators such as Net Present Value (NPV) and Internal Rate of Return (IRR). The DCF model is able to deal with the complexity of various factors involved in real estate valuation and to incorporate its related expenses, revenues, and risks simultaneously. For example, one of the most important assumptions in a DCF model is the discount rate that is used to calculate the present value of all future cash flow streams. The discount rate reflects the risk associated with receiving the projected cash flows. The discount rate, which is estimated using the Capital Asset Pricing Model (CAPM) method, is the sum of the rate of return of a risk free asset and a risk premium. The risk premium represents the additional return that the investor requires as compensation for taking on the additional risk of this particular investment. Thus, the discount rate on an asset is positively related to its risk, that means investing in a property with lower investment risk will result in lower risk premium and thereby a lower discount rate will be selected for that investment. This is how risk is taken into account in DCF modeling. The result of a study by Bowman and Wills (2008) has confirmed DCF as the most suitable method for assessing the valuation of green buildings. “Even though hard data is limited, the DCF approach allows valuers to factor in assumptions about the future shifts in value of Green Star buildings” [11]. “It [DCF analysis] provides the means to translate the “intermediate” sustainable property cost and benefit outcomes like health or productivity benefits, expedited permitting, or lower operating costs into financial measures like rate of return or net present value traditionally used by real estate capital providers” [8]. Thus, we encourage decision makers to use the concept of the DCF approach in lieu of simple PB, simple ROI, or LCC for estimating the financial performance of EEI alternatives. With the DCF method, potential direct and indirect costs, benefits and risks associated with energy efficiency investment, outlined previously, could be considered in generating the investment’s revenue.
Reporting Risk and Uncertainty of EEI Valuation: Monte Carlo Simulation Risk and Uncertainty “Risk and uncertainty relate to situations in which the performance measures have more than one possible outcome and the outcome is not known in advance”[12]. Risk is defined as a situation in which alternative outcomes and their probability of occurrence are known, where as uncertainty is a situation where information about future outcomes and their probability are not known. “Uncertainty is anything that is not known about the outcome of a valuation at the date of the valuation, whereas risk is the measurement of the value not being as estimated” [10]. Although, by definition, risk is a different from uncertainty, they are commonly used interchangeably in the context of property investment analysis. Uncertainty refers to the lack of knowledge of future events, which can lead to risk, whether it is a threat or an opportunity; and managing risk is really about managing uncertainty [22]. In the context of investment, risk is defined “as the extent to which the actual outcome of an action or decision may diverge from the expected outcome” [13]—the probability of not receiving the expected return. The variability of the expected return about its mean (the range of possible outcomes) is used as a description of risk, and the most popular measures of variability is variance—the spread of a probability distribution. Standard deviation is commonly used as a measure of spread. Risk and Uncertainty in the Valuation Process There is general agreement that there are risks and uncertainties associated with all valuation procedures which need to be identified, assessed, and reported in a way that can be understood and 95
analyzed by investors or end users. For example, the uncertainty associated with DCF inputs (assumptions about future factors) and risk of not achieving value or rate of return as predicted in DCF (estimation of DCF outputs). “Risk and uncertainty are inherent parts of the valuation process as often the valuer is unable to specify and price accurately all current and future influences on the value of the asset” [14]. “Uncertainty is a universal fact of property valuation. All valuations, by their nature, are uncertain” [10] and the acknowledgement of this fact would provide investors with useful information about the level of confidence in receiving their expected return and therefore, a key insight into of desirability of proceeding. “Risk is recognised as an inherent element within the valuation process and in the absence of perfect data across the property market it is likely that this situation will pertain to varying degrees. If risk cannot be eliminated the valuer is required to manage the analysis of risk within the valuation process so that its impact is minimised and the end user of the valuation can have confidence in the value estimate” [14]. The lack of consideration of risk and uncertainty inherent in valuation model such as DCF analysis requires a more sophisticated quantitative approach for the valuation process. Reporting Uncertainty “Despite the unquestioned necessity for reporting a single point estimate of market value for particular valuation assignments (e.g. financial reporting, financial performance measurement, court valuations, etc.) valuers should not proceed in reporting this figure only and in ignoring elements of risk and uncertainty. Valuers cannot be expected to predict the future but they can be expected to be transparent with regard to their assumptions even if they are (by nature) subjective, highly uncertain and maybe wrong from an omniscient observers’ perspective” [16]. “This identification of the most probable value and a range of values gives the client a measure of risk in the estimation of value. It translates the uncertainty in the key input variables into the final figures” [15]. Therefore, risk and uncertainty need to be measured and considered simultaneously with other issues of the valuation process; otherwise the outcomes of the valuation process may be overestimated or even underestimated, and may lead to inappropriate investment decisions. Accounting for uncertainties inherent in the valuation process and risks associated with achieving final financial performance indicators will improve the reliability of outcomes and also the confidence level of decision-makers in their decision-making process. This will impact the future reputation of valuers or consultants. In the proposed EEI valuation process, probability distributions are used for articulating risk and uncertainty. Probability distributions are the primary quantitative vehicle used for explaining risk or Value at Risk (VaR) in the risk management analysis methods. The probability distribution describes a range of possible values and the probability of any value within any subset of that range. All variables that are uncertain could be represented with probability distribution, and their associated risks could be estimated using statistical approaches based on specifications of a range of most likely values or extreme values. Monte Carlo Simulation “Monte Carlo analysis is a widely used numerical computational analysis tool that draws information from input probability distributions, applies the data in a process, and generates an outcome distribution” [4]. This technique is able to account for uncertainties by allowing for a range for each input and their correlations at the same time, perform a random probabilistic sensitivity analysis and model a range of possible outcomes. In the Monte Carlo simulation data is processed and ranges of final outputs are estimated through the base model which describes the relationship between inputs and outputs. The output will express the likelihood of the inputs’ and outputs’ occurrence along with their values’ probability distribution. The results—whether shown graphically or reported numerically with summary of statistics, such as mean, variance, standard deviation, skewness, etc.— would allow decision makers to better analyze and interpret uncertainty and would provide them with more reliable information than a few discrete scenarios. “Monte Carlo simulation provides a structured approach that explicitly incorporates uncertainty into decision-making models” [17].
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The Monte Carlo simulation technique has been suggested by many valuation experts to measure and express various risks and uncertainties in the valuation process by describing the range of possible values instead of a single-point estimate of value in the DCF model. Cash flows generated by Monte Carlo simulation provide more robust valuations than “traditional DCF valuations, permit the user to estimate the portfolio’s price distribution for any time horizon, [and] facilitate Values-at-Risk (VaR) computations”— estimation and presentation of risk with reference to the holding period and a confidence level [18]. In this paper, the Monte Carlo simulation is suggested for estimating the final financial performance indicators of EEI alternatives. The base model for this simulation, which describes the relationship between inputs and outputs, is built based the DCF approach. This probabilistic model takes and analyzes the same DCF inputs, such as rent, occupancy and tenant retention, and outputs, such as NPV and IRR, but replaces single estimate points with appropriate ranges and probability distributions. The Monte Carlo simulation incorporates the uncertainties of achieving the DCF inputs and articulates the risk related to receiving these outcomes by looking at various combinations of inputs across their different distributions, performing multiple simulations (random sensitivity analysis), and generating a distribution of financial outputs.
New EEI Valuation Framework Approach As stated previously, while the best way for understanding the financial performance of green systems in existing buildings is measuring their actual building performance, it is not possible for major retrofits analysis. It is the responsibility of valuers or energy consultants (who aim to estimate the value of energy efficiency) to use the available tools and data to project the building performance, analyze the market’s response to the forecasted performance, and select the financial model inputs. Therefore, understanding the bottom line financial performance of green systems mainly depends on the decision makers’ predictions about the building performance and market response to these predictions. However, most of the current studies in the area of green/energy-efficient buildings performance focus on the assessment of the systems performance and building performance outcomes, and would not directly tie them to financial performance. Muldavin (2009) has developed a “Green Building Finance Consortium (GBFC) Sustainable Property Performance Framework” which links the building performance to the financial performance through the assessment of market performance [8]. The proposed EEI valuation framework in this paper generally follows the process shown in Figure 1—adapted from the “GBFC Sustainable Property Performance Framework”—to derive the bottom line financial performance of each EEI alternative: Market Response
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Monte Carlo Simulation Final Report to Decision Makers
Figure 1: An EEI Valuation Process for Deriving the Financial Performance of EEI Alternatives This process is a path that decision makers, either technical people (design community) or property professionals (investment community) should go through in order to fully understand the effect of their selection of EEI alternatives on the building financial performance at the pre-development stage. It 97
translates the EEI impacts into the financial language to be included in a financial model and communicates the final financial performance indicators to the end users in reliable and understandable terms. The proposed framework takes an EEI alternative as a input, estimates its related outcomes, projects the new building performance resulting from new EEI investment, links the building performance to the DCF inputs by evaluating the market’s responses to the building performance, and finally, analyzes those inputs in the Monte Carlo model to derive financial performance indicators of the subject existing building. •
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EEI Alternatives: green systems or strategies that could result in greater energy efficiency including high-efficiency HVAC systems, lighting systems, daylighting, green roof, under-floor ventilation, motion sensors, high-performance windows, solar hot water heating, operable windows, wind turbine, energy control systems, building commissioning, etc. Energy Efficiency Outcomes: full potential impacts of EEI investment that could directly and indirectly influence building performance and ultimately, financial performance of EEI alternatives. These include electricity or gas consumption, indoor air quality, thermal comfort, CO2 emissions, air pollution, solar shading, natural ventilation, lighting, noise level, moisture transport, temperature and humidity distribution, air flow, glare, illumination, etc. Building Performance: includes both green building performance and non-green building performance. Green building performance, which are the factors related to the energy efficiency retrofits or EEI, include development costs (hard/soft costs, timing , tax savings grants and financing costs), resource use, occupant satisfaction, health, productivity, contribution to green or energy certifications, achievable government incentives, reputation, marketability, public benefits, development and cash flow risks, etc. Non-green building performance, which are the critical factors in valuation of a property and not related to the retrofits, include location, access, age, size, security, market condition, etc. Financial Model Inputs: the financial model suggested for this process for estimating the financial performance is a traditional Discounted Cash Flow (DCF) model. The inputs of the DCF model for estimating the revenue of the building include: market rental rate, annual rental growth, building costs (such as operation cost, leasing expenses, tax and capital cost), occupancy, absorption rate, tenant retention, discounted rate and capitalization rate. Financial Performance: contains factors that people from investment communities are primarily concerned with when making decisions. These include revenue, IRR, NPV, etc.
The Process Steps, Methods and Considerations As shown in Figure 1, there are four main steps in the proposed process that decision makers need to follow in order to understand the financial performance of the selected EEI. It should be noted that in this paper we do not aim to provide any detailed information or guideline about data estimation, collection or forecast in each step of the proposed process. The primary goal here is to provide professionals who are involved in energy efficiency consulting or decision making with a new framework for evaluating the EEI alternatives. Below, the four main steps are presented: Step 1: Building Modeling As stated previously, energy-related systems’ and strategies’ may contribute to other performance mandates such as indoor air quality or thermal comfort. Their impacts are beyond the direct energy cost savings but important to be considered in valuation. The reason that these indirect-impacts on building performance mandates or “non energy cost saving” are important in valuation is that any building performance indicator that is of interest to occupants could play a role in the financial performance of a building. Several studies have confirmed that the outcomes such as thermal comfort, indoor air quality, or acoustical performance would affect the occupant performance, such as occupant satisfaction, health and productivity. These factors potentially increase demand, influence the financial model inputs such as absorption rate, vacancy rate, etc., and ultimately improve the bottom line financial performance. Thus, it is important to realize that there are other building performance outcomes beyond energy conservation or direct energy costs savings that impact the financial performance of a building. We encourage users to model the existing building with each new EEI with more than one simulation program for a thorough valuation. The users need to identify the potential outcomes of EEI they are 98
interested in evaluating, carefully assess the capability of available modeling tools, and ultimately select the most appropriate tools that match their requirements. For example, if the users are only looking at evaluating energy consumption, they might use eQuest or EnergyPlus, but if they feel that the EEI might have impacts on indoor air quality or daylighting quality, they might need to model the building with a Computational Fluid Dynamics (CFD) modeling tool or Radiance Interface. The U.S. Department of Energy has suggested a list of “whole building simulation” tools [3] that users could go through these lists and select the appropriate tools based on the types of the decisions, building systems (inputs) and building performance (outputs) they are interested in evaluating. Step 2: Building Performance Forecasting Green building performance includes factors that could be influenced by the energy efficiency investment. When evaluating a specific property, development and operation costs, resource use, possible achievable certifications and incentives, can be estimated relatively easily based on available data, guidelines, regulations, and modeling tools. However, factors such as users’ satisfaction, and health and productivity are more difficult to measure precisely. Currently, establishing the precise quantitative relationship between performance outcomes, health/productivity and market value seems to be almost impossible, due to limited data and difficulty in obtaining required information in a way that can be used directly in property level decision making. However, in the real estate investment world, perfect science or exact knowledge about the potential health/ productivity benefits of sustainable property is not required. What is required is appropriate caution in the use of health and productivity studies so as not to mislead decision-makers based on incorrect or incomplete presentation of results and caveats [8]. Therefore, it is particularly important that decision makers acknowledge the potential benefits to occupants and consider the occupants’ response to those benefits that result from EEI investment, even if the exact quantitative data is not available. Step 3: Financial Model Inputs The traditional DCF approach is suggested to build up the base model for estimating the financial performance of the existing building with new EEI alternatives. This approach is able to thoroughly incorporate the potential direct and indirect costs, benefits and risks associated with energy efficiency/green building investment in generating the investment’s revenue. This step is a translation from technical to financial language. In this step, all the technical details concerning energy efficiency outcomes and information about building performance are translated to DCF inputs such as rents, occupancy, absorption rate, operation and financing costs, etc. There are two important challenges in determining the DCF inputs: One is the nature of this analysis, which requires a simultaneous consideration of many factors, both green and non-green, in order to determine the DCF inputs to ultimately derive the property value (revenue and risk). In fact, the impact of green factors on the financial model inputs are typically limited when compared with the non-green factors and therefore, improvement or decline in financial performance of a green building could be primarily due to other non-green factors. The good news for existing buildings is that all non-green factors do not change after implementation of the green/energy retrofits. Having considered all nongreen factors being equal in property valuation, all changes in the projected cash flow will be related to the DCF assumptions that are influenced by the selected EEI alternatives. Therefore, the procedure will measure and numerically communicate the market value added by investing on those selected EEI alternatives in the subject existing building. Another challenge is related to the valuation process of all building types, either green or non-green: that is a consideration of both quantitative data and qualitative judgment in determination of DCF inputs. In order to select financial inputs, for each specific property the real estate valuers (underwriters, appraisers, due diligence persons) have to do as much research as possible in order to collect all related quantitative results, as well as other qualitative information. They must consider all the results and information simultaneously and assess the expected behavior of regulators, investors and space users (key driver of property value) for that particular market. “While the impact of green strategies may be clear in one market, it is the valuer’s responsibility to determine the market environment for high performance green features on a case-by-case basis” [19]. Adair & Hutchison (2005) also pointed out that “while the final single point estimate of value may become a statement of fact in the minds of the users of the valuation it nevertheless remains the opinion of an expert [valuer]” 99
[14]. It is not possible to develop a robust tool in order to perform this translation and produce the final financial inputs, such as a rent, to be directly included in the DCF model. Data has to go through a qualitative filter. Valuers are the ones who do this translation from technical language to financial language by integrating quantitative data from simulation tools or other assessment techniques with other qualitative information about specific subject property, and evaluating market response to the data and information in a specific situation. Step 4: Uncertainties modeling and financial performance estimating It is widely accepted that all forecasts about the future involve a certain amount of uncertainty. In the proposed valuation process, in each step all estimations and outcomes are based on projection, either objective, such as energy modeling, or subjective, such as DCF inputs selection. Therefore, there is a certain amount of uncertainty associated with measuring the outcomes of each step in the valuation process. Some of these uncertainties include: Uncertainty in Step 1: The degree of uncertainty associated with forecasting the potential energy efficiency outcomes. Uncertainty in Step 2: The degree of uncertainty in determining the building performance, such as health and productivity based on projected outcomes, such as ventilation rate, level of noise, lighting, etc. Uncertainty in Step 3: The degree of uncertainty about forecasting the financial model inputs due to limited sales data and absence of a robust pricing model on green buildings as well as the difficulty of precisely determining the impact of green investment on a property value. These are examples of the types of uncertainty associated with the energy efficiency valuation process that need to be considered in order to communicate reliable outputs to final decision-makers. Thus, we suggest specifying a probability distribution for all variables that are uncertain. A schematic diagram demonstrating the function of the proposed valuation process is shown in Figure 2. We suggest Monte Carlo model to estimate the final financial performance of EEI alternatives, while simultaneously incorporate and articulate uncertainties of the valuation process. This model will apply and measure various uncertainties in the valuation process by ascribing the range of possible outcomes, in order to communicate how the selection of EEI impacts the range of possible expected value with its confidence interval.
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Figure 2: A Schematic Diagram for Demonstrating the Function of the EEI Valuation Process 100
The resulting ranges and the shape of distributions would reflect the uncertainty related to the estimation of simulation inputs (DCF inputs) and articulate the risks related to achieving the simulation outcomes (DCF outputs), which ultimately assist final users to make a better investment decision. For example, the tighter distribution of outcome with smaller standard deviation represents the lower risk and uncertainty and therefore the higher level of confidence that investors will receive the predicted outcome (mean). Flat distribution with large standard deviation denotes the great degree of risk and uncertainty and therefore, less confidence investors could be in achieving the expected outcomes. Final Statement for the Decision Makers Finally, the results of the process will be reported to decision makers in the form of a more simple and understandable statement. The simulation results, along with a description of alternative outcomes and their probability of occurrence, will be presented either in simple matrices or clear graphics. This final statement must be very clear and easy to understand for end users. The details of the development of the input data and simulation processes do not need to be included in the report for investment decision-makers. As mentioned previously, investment communities are more concerned with the final key financial indicators as opposed to the technical details in the process. However, the details would be available to the decision makers if they would like to check the assumptions used in the valuation process to increase their level of confidence.
Conclusion The current energy simulation tools, widely used by decision makers, do not simultaneously incorporate all of the costs, benefits, risks and uncertainties of EEI investment, nor represent them in appropriate terms to be understood and utilized in the investment decision-making process. None of them on their own are sufficient to rely upon for making high-quality investment decisions for major EEI. Relying solely on their simulation results often undervalue the energy efficiency and therefore, many EEI profitable investment opportunities may be excluded from consideration. In this paper, a robust valuation process is suggested to connect building performance estimates from the design professionals to the more sophisticated financial tools used by property professionals to measure the financial impact of EEI alternatives and represent them in a reliable and understandable language. Its final outputs would provide decision-makers with a much more comprehensive view of investment outcomes, as opposed to traditional single-point estimates of conservative simple PB or ROI, and a clearer idea about inherent risks and uncertainties in the valuation process. The proposed process is a systematic framework that final users, both design and investment communities, could follow to better understand the true value-added by each EEI alternative as well as risk and uncertainty associated with achieving their possible additional returns on investment. They could compare the final market value of a building with different EEI alternatives and select the best possible EEI alternative for greening their buildings. In summary, the following principles are suggested throughout this paper for evaluating energy efficiency investment and also considered in development of the proposed valuation framework: 1.
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There is inaccuracy/error inherent in building modeling forecasts. The actual building performance may differ from what was projected by BSPs. It is critical for decision makers to consider this inaccuracy/error to avoid overestimating or underestimating the building performance when making decisions based on the actual performance. Any building performance outcome that is of interest to occupants could play a direct role in the financial performance of a building and therefore, are important to be considered in energy performance valuation. It is not just energy cost saving that matters. We suggest modeling the existing building through different modeling tools in order to evaluate as many performance outcomes as possible that might have impacts on occupant performance. Simple cost-based financial methods, such as simple PB, simple ROI or LCC, fail to address the true value of energy efficiency investment, both revenue and risk, and therefore, ignore many energy efficiency costs and benefits. Instead, we suggest to utilize the concept of DCF approach for the estimating the financial performance of EEI alternatives. With the DCF method, potential direct and indirect costs, benefits and risks associated with energy efficiency investment could be considered in generating the investment’s revenue. 101
4.
5.
There is a degree of uncertainty associated with the forecasts in each step of EEI valuation process. Careful consideration of uncertainty is of vital importance in providing more reliable data to decision makers. We suggest introducing ranges and distributions for reporting the forecasted factors in order to incorporate and articulate the risks and uncertainties inherent in the EEI valuation process. We propose the Monte Carlo simulation to estimate the final financial performance indicators of EEI alternatives. The base model for this simulation, which describes the relationship between inputs and outputs, is built based on the DCF approach. This probabilistic model takes and analyzes the same DCF input and outputs, but replaces single estimate points with appropriate ranges and probability distributions.
Reference [1]
Ciochetti, B. A., & McGowan, M. D., Energy Efficiency Improvements: Do they Pay? Cambridge, MA: MIT Center for Real Estate, 2009.
[2]
Nelson, A. J., How Green a Recession? – Sustainability Prospects in the US Real Estate Industry San Francisco RREEF Research, 2009.
[3]
DOE, Energy Efficiency and Renewable Energy: Building Energy Software Tools Directory, 2009, from http://apps1.eere.energy.gov/buildings/tools_directory/subjects_sub.cfm
[4]
Jackson, J., Energy Budgets at Risk (EBaR): a risk management approach to energy purchase and efficiency choices: John Wily & Sons, Inc, 2008.
[5]
The simple financial outcomes of these modeling tools might be good enough to address minor investment decisions, such as minor retrofit or making decisions among competing HVAC systems, or window products, but are not sufficient for major retrofits or acquisition decisions.
[6]
This paper is primarily concerned about EEI costs-benefits from perspective of private sector.
[7]
The results of few studies have shown that buildings with higher level of green certification had higher inaccuracy in their projections.
[8]
Muldavin, S., Underwriting Sustainable Property Investment: Green Building Finance Consortium, 2009.
[9]
Hong, T., Chou, S. K., & Bong, T. Y., Building simulation: an overview of developments and information sources. Building and Environment, 2000, 35(4), 347-361.
[10]
French, N., & Gabrielli, L., Discounted Cash Flow: Accounting for Uncertainty, Journal of Property Investment & Finance, 2005, 23(1), 76-89.
[11]
Bowman, R., & Wills, J., Valuing Green: How Green Buildings Affect Property Values And Getting The Valuation Method Right.: The Green Building Council of Australia, 2008.
[12]
Aven, T., Foundations of Risk Analysis: A Knowledge and Decision-Oriented Perspective (1st ed.): John Wiley & Sons, Ltd., 2003.
[13]
Hargitay, S., & Yu, S.-M., Property Investment Decisions: A quantitative approach (1st ed.): Taylor & Francis, 1993.
[14]
Adair, A., & Hutchison, N., The Reporting of Risk in Real Estate Appraisal Property Risk Scoring. Journal of Property Investment & Finance, 2005, 23(3), 254-268.
[15]
Boyd, T., Property Cash Flow Studies: Focusing on Model Consistency and Data Accuracy. CRC Construction Innovation, Project 11 – 5, 2002.
[16]
Lorenz, D., Trück, S., & Lützkendorf, T., Addressing risk and uncertainty in property valuations: a viewpoint from Germany. Journal of Property Investment & Finance, 2006, 24(5), 400-433. 102
[17]
Kelliher, C. F., & Mahoney, L. S., Using Monte Carlo simulation to improve long-term investment decisions. The Appraisal Journal, 2000, 68(1), 44-56.
[18]
Baroni, M., Barthélémy, F., & Mokrane, M., Monte Carlo Simulations versus DCF in Real Estate Portfolio Valuation, 2006.
[19]
Chappell, T. W., & Corps, C., High Performance Green Building: What’s it Worth? Washington State Department of Ecology, 2009.
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Calculating life cycle cost in the early design phase to encourage energy efficient and sustainable buildings Gerhard Hofer1, Bernhard Herzog2, Margot Grim1 1 2 e7 Energie Markt Analyse GmbH, M.O.O.CON GmbH
Abstract Consideration of Life Cycle Costs (LCC) during the planning phases of buildings is insufficient. The reasons for this are that on the one hand, the focus of clients for whom a building is being built most often remains on the initial investment costs. On the other hand, available software tools are complex and the data needed to use them properly is vague during the early design phase – the phase where cost minimising can be most efficient. Thus, on the basis of various existing Life Cycle Cost tools, a method and tool has been developed so that detailed forecasts of expected Life Cycle Costs can be made during early planning phases. The new method can illustrate the characteristic values of space efficiency, energy efficiency, and cost efficiency of the investment and operation while presenting an overview of Life Cycle Costs. This is facilitated through: • • •
aggregated building elements with investment costs and operating costs in varying levels of detail; a virtual building model for entry of space allocation and function programs as well as architectural concepts; and an energy calculation tool.
In this way the long-term economic impact of energy efficient buildings can be illustrated.
Introduction Current methods in construction show that in most cases investment cost is still a decisive factor in the construction of a building. However, increasingly it can be seen that the sustainability of a building plays an ever more important role. Currently, there is a high demand for buildings with low operation costs and sustainable building certification that is more detailed than a standard due diligence because of the current real estate market crisis and a changing buyers market. Life Cycle Cost is included as a specific criterion in both the German Sustainable Building Council’s certification (Deutsche Gesellschaft für Nachhalitges Bauen (DGNB)) [1] as well as in the Austrian certification for a Total Quality Building [2]. At the international level the International Organization for Standardization (ISO) has developed a standard for the calculation of LCC. With use of ISO 15686-5 [3] LCC can be calculated. Still, values for important parameters like system boundaries, periods of analysis and cost structure are not defined by this standard. In order to improve competition in the field of sustainable construction the European Committee for Standardization (CEN) commissioned the preparation of a standard method for the calculation of LCC for buildings. The final report [4] delineates a generally applicable process for the calculation of LCC. The European Commission is attempting to develop criteria for standardizing the measurement of sustainable construction, in order to develop a uniform European-wide evaluation method. Standardization proposals are being developed by CEN’s Technical Committee 350. Workgroup 4 of the committee is working on Standard EN 15643-4 [5] for the assessment of economic performance. LCC are a significant indicator for the economic sustainability. After all, the impact of LCC plays an important role in the value of the real estate. As part of the 104
European project IMMOVALUE [6], research and analysis was conducted on energy efficiency (based on the energy certificate), LCC and property value. Findings gathered through interviews [7] showed that sustainable buildings have a higher marketability. At the same time, a clear correlation can be seen between lower operating costs and higher net rent revenues. This shows that consideration is given to the inclusion of operation costs in rental costs. International research [8] has shown that sustainable buildings generate higher rent revenues and incur shorter vacancy periods. These various factors and activities show the growing interest for the methodology of LCC observation both at the political level and in the field of construction. This method allows for the operating costs of a building to be taken into account at the time of initial investment. Additional information about future operating costs can already be ascertained during early planning phases, thereby creating a better basis of available data for planning sustainable buildings. Today it is common that the projected investment and operating costs of buildings are based on benchmarks of existing buildings (eg. BKI [9], Oscar [10]). Top-down approaches do not exist in sufficient detail to be used in the early planning phases of a building, when different types of building systems with altering costs have to be compared. These approaches are based on categories such as: air-conditioned or non-air-conditioned office buildings without taking into account the particulars of the building design or technical equipment in use in the building. Furthermore, concepts for energy efficient office buildings or those that implement alternative energy systems are not taken into consideration, or insufficiently so. Since specifications are relevant to the past, naturally they cannot be representative of current sustainable building designs. Existing software tools for calculation of LCC (e.g. Legep [11], BUBI [12], Baulocc [13] available on the German-language market) are based on the bottom-up approach, which makes it necessary to enter itemized data (i.e. lime cement plaster, or type of paint coating/finish of paint). On the one hand this requires a great deal of data entry while on the other, the data is simply not available at the required level of detail in the initiation and early planning phases. A quick simulation of different variations, as it is necessary in an iteration process with an integral planning approach, is only possible by spending a lot of time and effort. INITIATION PHASE
CONCEPT PLANNING PHASE
DESIGN PHASE
TOP DOWN APPROACH
BOTTOM UP APPROACH
Oscar, BKI,
35% LCC
CONSTRUCTION PHASE
Legep, Bubi, Baulocc,...
40% LCC
NEW LCC APPROACH
CLIENT‘S BRIEF
OPTIMIZATION OF BUILDING CONCEPT
OPTIMIZATION OF BUILDING COMPONENTS
Figure 1: Influence on costs and fields of application for existing tools (Source: original illustration) Likewise, there are countless software programs which calculate economic efficiency or programs for calculating LCC (e.g. LCProfit), that do not come with any cost data pre-sets. Therefore, in order to calculate LCC the first task is to determine construction and operating costs of the building which again, requires extensive time and effort in the early planning phases. 105
It is exactly in the initial planning phase, that taking the long-term economical implications into account is most decisive. Approximately 80% of all investment and operating costs are determined in the initial and early planning phases [14]. Therefore, it is of the utmost importance to optimize systems in these first phases.
Research Objectives Level of building elements in decision making process The goal of the project was to develop a method of calculating LCC in order to provide clients for whom a building is built with a well-founded basis for decision making in order to: • optimize requirements during programming and setting up the brief, and • select the correct systems in preliminary designs and drafts during the planning phases. Through the integration of this method into a software-based tool with an acceptable input of time and effort, it should be possible to make reliable statements on prospective investment and operating costs of the building and thereby accelerate the realization of sustainable and energy efficient construction concepts.
Methodological Structure In order to combine the advantage of the fast cost estimation of the top-down method with the advantage of the accuracy of the bottom-up method it was necessary to take on a new approach. At the same time, the decision-making process in the planning phase was incorporated into the method with great detail. In general, decisions are made mainly at the strategic and system levels during the phase before the construction of a building [15.]
Level of decision in Initiation & Design Phase
Figure 2: Levels in the decision-making process (Source: Life Cycle Costs in Construction [15]) The goal of the newly developed method was to model the building in such a way that LCC could already be calculated in the early planning phases. Even, at a point of time when no design for the 106
building is yet available. To this end both tools for generating the space allocation program and volume program for the building, as well as data for construction costs and operating costs are necessary on an aggregated level. This allows for entries to be made at the beginning of planning. In addition, an energy calculation tool should illustrate the interdependency between the building design, the facade, and the building equipment system. In this way, no additional calculation tool is needed. The method and the tools should be designed so that LCC analysis can be carried out well into the detailed design phase, i.e. when preparing detailed information for construction. INITIATION PHASE
CONCEPT PLANNING PHASE
DETAILED DESIGN PHASE
CONSTRUCTION PHASE
REQUIREMENTS
Check
Check
DEFINITION OF REQUIREMENTS
DESIGN SOLUTION
OPTIMIZATION OF BUILDING CONCEPT
OPTIMIZATION OF BUILDING COMPONENTS
Figure 3: Areas of application of the LCC tool from initiation through to the detailed design phase (Source: original illustration) Option 1: General building data via virtual building model For the modelling of the building, a virtual building model was developed. This virtual building model is based on the experience of the company M.O.O.CON acquired as part of their client consulting on office buildings. Based on the requirements of the client’s brief, the virtual building model can calculate the approximate volume and surface area of the building at a time where no design drafts for the building have been put forward. Apart from the calculation of volume and surface area this tool can also optimize usable floor space. Optimising the use of floor space is a powerful lever for the reduction of construction and operating costs. Through the reduction of conditioned volume, energy costs can also be reduced. In this process office spaces and other special areas in the building are combined in different design variations into floors and building cores and the gross floor space is calculated. Thus, it is possible to optimize the floor space even at this point of time, which in turn leads to lower follow-up costs (see figure below).
Figure 4: Output of floor space values per building sector and number of cores. (Source: M.O.O.CON) Option 2: General building data by using architectural concept With the introduction of an architectural concept, the data in the virtual building model is changed in accordance with the significant geometrical dimensions (essential building area data, facade, building 107
orientation). With minimal additional effort for data entry the existing data can be optimally used. Relevant areas in office buildings in the decision making process Concerning the building, the impact of the various usage areas on cost is investigated. Here the focus is to outline the effect of special areas on cost compared with main usage “office” spaces. The primary utilization of an office building, as the names suggest, is for office and administrative use. The main usage areas are complimented by decentralized spaces such as staircases, elevators, restrooms, as well as centralized special usage areas such as conference rooms, the lobby, cafeteria(s), storage areas or carports. The essential system decisions are made based on the main usage which also generates the main source of costs. Consequently, the building elements for the main usage areas (“office” spaces) need to be provided at a different level of detail than for the special usage areas. Based on cost analysis, buildings elements were defined at different levels of detail. Depending on the influence of the usage, aggregation of the building elements was carried out at a different level. For the main usage area, “office”, cost relevant issues are compiled at the level of elements (as defined by Austrian Standard ÖNÖRM B 1801-1[16]), for less cost relevant issues or building elements in less cost relevant usage areas at the level of cost ranges (as defined by ÖNORM B 18011).
Main core
Side core
Office area
Office area
Conference (special area)
Lobby, restaurant (special area)
Garage (special area)
Store room (special area)
Garage (special area)
Technikfläche (special area)
n Area with high standardisation (office): o element / quality n Special areas/ categorization in: o simple standard o middle standard o high standard
Figure 5: Structure of costs for the main usage “office” space and special usage space (Source: original illustration) The building elements were consequently compiled from bottom-up aggregated items for the relevant cost drivers in the office areas (i.e. type of floor, type of heating system). For less relevant costs ranges and usages in special areas, they were bottom-up aggregated and tested against top-down benchmarks, as a certain imprecision can be tolerated. Thus the number of elements and consequently the amount of data entry is reduced significantly. Calculation costs for defined building elements Different sources were referred to for an estimate of the investment cost. These sources included the experiences of the large Austrian construction company Allgemeine Baugesellschaft - A. Porr Aktiengesellschaft, and the analysis of their AVA software as well as the experiences of the large Austrian building equipment supplier Axima Gebäudetechnik GmbH and the engineering office Allplan GmbH. For an assessment of the operating costs the database of Axima Gebäudetechnik GmbH,also the largest building management company in Austria, was analysed. These figures were integrated into a database that was specially developed for this method. In order to ascertain the total cost of the elements comprehensive building data is necessary. This can be gathered based on the virtual building model or the architectural concept. As with the aggregation of the building elements, it was also necessary to keep the amount of required data to a minimum for the calculation of comprehensive building data. Calculation of Life Cycle Costs 108
Again the results of the analysis of the cost drivers were referred to and an attempt was made to incorporate only a few significant parameters from the plans. All other data should be calculated by algorithms based on these entries. The algorithms are derived from planning regulations for office buildings, fire safety regulations, work space regulations and years of experience of various projects of M.O.O.CON. The significant parameters for the efficient use of space such as width and structure of building could be easily entered and changed. The data entry is done through a space allocation and function program used by M.O.O.CON in the initiation phase. Common measurements of architectural plans provided at this time are used as a basis during the early planning phases. Building elements could be defined and associated with investment and operating costs based on the structure of the usage area as well as significant system decisions, which contribute to the comfort of the interior (acoustics, visual comfort). For a usage area such as a cafeteria, this meant the definition of different building elements for different standards at a level of costs ranges (such as “high quality cafeteria”). For the office areas building elements for flooring, floor construction, office partitions, hallway dividing walls, noise insulation, etc. were defined. (e.g. office area, flooring, carpeting, high quality). For the building itself, building elements such as facade, HVAC and many more had to be defined. Based on the virtual building model of selected building elements and user specified comfort guidelines, it is now possible to calculate energy consumption based on the calculation for the energy certificate complemented by several significant factors such as: the influence of thermal mass, different usage areas, the taking into account of daylight, the actual energy consumption of different utilities like lighting, cooling, heating and ventilation. Thanks to years of experience of the employees of e7 Energie Markt Analyse GmbH very realistic energy usage scenarios could be compiled. Through the programming of a software interface the entry of the virtual building model and of the building elements could be directly linked to the energy cost calculation, making any additional step unnecessary. The linking of the building elements to the use of energy calculation allows for an additional correlation between building design and heating and cooling load of the building’s central equipment system. Heating and cooling loads are calculated through the entry of the buildings volume and facade design. These loads are indicators for the selection of the dimension of the building equipment systems for heating and cooling. An improved insulation of the facade contributes directly to lower investment and operating costs of the building equipment systems. The chosen method of calculating the energy costs also allows for the selection of alternative energy systems such as heat pumps, photo-voltaic and thermal solar systems. Based on investment and operating costs provided on a per-element basis (originating from the building elements) as well as building specific calculated energy costs it is now possible to calculate LCC using the net present value method or the method of complete financial plans. By changing significant parameters (inflation, construction cost index, energy cost index, depreciation period and financing options, etc.) their effect can be simulated. Sensitivity analysis can be done by changing the entered value for calculations. Cost parameter of the building can be varied in Excel allowing for a risk analysis of individual parameters to be carried out.
Realization of a LCC Software tool The different elements are connected to form a complete, functioning tool in the form of software that was developed by Alpha Carinae KEG in Austria. An array of factors influences the relationships and recognizes the impact of hi-tech, large, complex system components on one another. These interdependencies were derived on the basis of expert interviews with those providing the data. The software user interface incorporates the use of several Excel tools and a costs database.
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Figure 6: User interface of the LCC tool (Source: original illustration) The set-up and follow-up costs of the aggregated building elements are deposited in a database that can be used and maintained independently from the LCC software.
Figure 7: User interface of the costs database (Source: original illustration) The software provides results with different degrees of aggregation so that, depending on the required aspect of optimization, all of the data is available for viewing in various well-sorted overviews and illustrated with graphics. Significant expenditures are: • Construction costs (total/ by cost areas/ by building elements) • Operational costs (total/ by type of costs/ by building elements and cost catagories) • Gross floor area (total/ by utilization areas/ by space) • Energy consumption (total/ by causer (cooling, heating, lighting, work equipment, other) • A graph of LCC It is possible to compare different variants with each other; specific values of other projects can be taken up for comparison as well.
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Figure 8: Aggregated output of the LCC Tool (Source: original illustration)
Results In the final test phases investment cost and operating cost data, derived from completed and operating buildings, were compared with corresponding results generated by the tool. Through this data it was possible to test the programmed algorithms and the cost estimates and make any necessary change. After the testing phase was complete, it was possible to confirm, that the chosen approach lead to extremely short data entry times. At the same time the cost reliability achievable in this early planning phase remained within the margins of +/- 10 to +/- 20% for all simulated projects. Thus, it could be shown that with sufficient knowledge of significant cost drivers the simulation effort can be minimised without compromising on data reliability.
Future Prospects After first applications of the method where results with high cost reliability for existing buildings were achieved, it is now implemented for the planning of new office buildings. Nevertheless, there are also other possible areas of application where the developed LCC method could be implemented: renovation of office buildings, other categories of buildings such as schools, nursing homes, or residential buildings. In addition, other indicators will be incorporated into the tool: the rating of ecological materials, comfort, etc. The method and the software will be gradually expanded over the next years, so that a complete sustainability assessment will be possible in the early planning phases with minimal effort.
References [1]
Deutsche Gesellschaft für Nachhaltiges Bauen e.V., Deutsches Gütesiegel für Nachhaltiges Bauen, Aufbau – Anwendung – Kriterien. Issue 3/2009. Stuttgart, 2009.
[2]
Lechner, Robert: TOTAL QUALITY BAUEN: Ergänzung und Erweiterung des bestehenden Gebäudebewertungssystems, Wien, 2009. 111
[3]
ISO 15686-5:2008 06 15: Buildings and constructed assets -- Service-life planning -- Part 5: Life-cycle costing, Genf, 2008. Can be ordered from www.iso.org
[4]
Davis Langdon Management Consulting: Life Cycle Costing (LCC) as a contribution to sustainable construction: a common methodology, London, 2007.
[5]
prEN 15643-4:2009-12-31 (working draft): Sustainability of construction works — Sustainability assessment of buildings — Part 4: Framework for the assessment of economic performance, Brussels, 2009.
[6]
IMMOVALUE, Improving the market impact of energy certification by introducing energy efficiency and life-cycle costs into property valuation practice, IEE/07/553, www.immovalue.org.
[7]
Bienert, Sven et al.: Integration of energy efficiency and LCC into property valuation practice, paper for the 15th PRRES Conference, January 2009, Sydney. Download at www.immovalue.org.
[8]
Fuerst, Franz; McAllister, Patrick: Green Noise or Green Value, Measuring the Price Effects of Environmental Certification in Commercial Buildings, Reading, 2008.
[9]
Baukosteninformationszentrum Deutscher Architekten: Statistische Kostenkennwerte für Gebäude, www.baukosten.de.
[10]
John Lang Lassalle: Büronebenkostenanalyse OSCAR 2008, Berlin, 2009. Can be ordered from www.joneslanglasalle.de
[11]
LEGEP Software GmbH: LEGEP Bausoftware, bauen berechnen betreiben; Ein Werkzeug für die integrierte Lebenszyklusanalyse, www.legep.de.
[12]
Riegel, Gert Wolfgang: Ein softwaregestütztes Berechnungsverfahren zur Prognose und Beurteilung der Nutzungskosten von Bürogebäuden, Darmstadt, 2004.
[130] Herzog, Kati: Life Cycle Costvon Baukonstruktionen – Entwickl. eines Modells u. einer Softwarekomponenten zur ökonomische Analyse und Nachhaltigkeitsbeurteilung von Gebäuden, Darmstadt, 2005. [14]
Statsbyggs: LCProfit, www.lcprofit.com.
[15]
European Comission, DG Enterprise and Industry: Task Group 4: Life Cycle Costs in Construction, Brussels, 2003.
[16]
ÖNORM B 1801-1:2009 06 01: Bauprojekt- und Objektmanagement - Teil 1: Objekterrichtung, Wien, 2009.
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Economic barriers to low-carbon office refurbishments Giuseppe Pellegrini-Masini1, Dr David Jenkins1, Gary McLaren2, Dr Graeme Bowles1, Ross Buchan2 1 Heriot-Watt University, 2Thomson Bethune Keywords Carbon emissions, offices, life-cycle costs, refurbishment
Abstract Much research exists on the technical potential of different carbon-saving measures in the nondomestic building stock. However, it is clear that the carbon-saving targets for retrofit projects are extremely challenging, largely due to the practical and economic constraints related to such a scale of change. The Tarbase project has looked at carbon-saving technologies across the non-domestic and domestic stock in the UK. Included in this work is a wide-ranging analysis of technologies suited to the office sector, both related to demand-side and supply-side measures. This paper will present the economic analysis of some of these measures, which are designed to achieve carbon savings of 50% or more. Several virtual, modelled case-studies will be used as examples of carbon-saving packages that might be suitable for UK offices (relating to previous project outputs). Developed quantity surveying tools are then used to cost these measures based on a range of assumptions relating to installation, operation and maintenance. A whole-life cycle costing approach using Net Present Value calculations is adopted over a 30-year period. The results are discussed in relation with the findings of a qualitative survey of stakeholders of the UK office market. This survey suggests what the main drivers and barriers might be behind the uptake of energy efficiency measures in office buildings. Particularly it has emerged that stakeholders are motivated towards reducing carbon emissions in offices mainly for corporate social responsibility reasons, which can influence their public image and their attractiveness towards clients, employees and investors. Nevertheless occupiers show a lack of willingness to pay higher rental rates for energy efficient offices. It is concluded that, for occupiers, overcoming the hurdle of high capital costs for carbon-saving technologies with long, or non-existent, payback periods is not likely to be viable in current market conditions. In some cases, the capital cost alone might be enough to dissuade occupiers from purchasing a technology, regardless of any future effect on energy bill savings. Equally, it is unlikely for investors to undertake the risk of costly refurbishments in a market where higher values are not recognized for energy efficient office buildings.
Introduction A multi-sector approach throughout the UK [1] will arguably be needed to meet the legally binding target of reducing carbon dioxide emissions by 80 percent by 2050, set by the government with the Climate Change Act [2].In 2008 workplaces were responsible for about 12% of UK greenhouse gas emissions [2]. Looking for the potential of carbon abatement in the business sector, the Carbon Trust [3] found that with exception of the energy-intensive industries, the main potential of cost effective abatement was within energy use in buildings, whose projected growth is the most rapid. If we look more closely at the commercial office buildings context, two figures are particularly significant. First, a survey by CABE and BCO [4] found that mechanical and electrical (M&E) running and maintenance costs’ of a building amount to only 4% of the total costs of a business, while the salaries of the staff hosted in the building amount to 85%. Thus, on the basis of business costs alone, high carbon emitting activities are unlikely to pose any significant financial burden to businesses. To compound this problem, building occupiers are rarely faced with the financial costs of high carbon emitting activities (M&E related costs) in a direct manner. In the UK, M&E running and maintenance costs are simply a component subsumed within the service charge of a building. A leading argument is that the service charge represents a relatively low element of overall building occupation costs for office occupiers, rent being the major cost and hence at the forefront of occupiers’ concerns. At the beginning of 2007 the average rental rates for London in the City area (prime sector), were £62.5 per square foot (psf) [5] while in 2007 the average service charge for an air conditioned (AC) office was, in the same location, £ 7.54 psf [6]. In 2009 (third quarter) the average rent for offices in the City (prime sector) is lower than in 2007: £42 psf [7]; nevertheless even with this lower rental value and considering the average service charge unvaried from 2007, the service charge would represent no
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more than 15% of rental occupancy costs and an even a smaller proportion of total occupancy costs (including rates – commercial property taxation on occupiers). Furthermore, in 2007 it was found that electricity and gas costs combined accounted for an average of approximately 20% of the whole service charge for AC City office (prime sector) [6]. So the total energy costs for an air conditioned office would amount to just 3% of occupancy costs in the case mentioned above (London, City area, prime sector). Therefore, it is apparent that there is a very limited financial incentive for businesses to reduce energy consumption in the United Kingdom office sector. Given that this is the case, it could be argued that a cost effective investment in energy efficient technology would be difficult to achieve unless the capital cost of these technologies were sufficiently low. It could be postulated that the 2008-2009 economic crisis has made corporate estate managers more cautious about investing in the, nonetheless, popular cause of business sustainability. A global survey of corporate estate executives by Jones Lang LaSalle [8] found that 74% of them are willing to pay a premium to retrofit energy efficient technologies in owned office space but principally with a cost saving perspective in mind. Also, 42% of them said that they would not pay higher rental rates for rented office space and 21% that they would, but only if these were offset by lower operating costs. If these findings were universal, in a market which is largely made of rented office space, this might dampen the interest of investors in paying more to acquire, in their portfolios, energy efficient buildings. Nevertheless, the short term perspective of higher rental rates might be just one of the factors driving more investment in sustainable offices, with long term asset value [9] and building pressure of shareholders two more factors sustaining investors’ demand [9-11]. Within this context, this paper will assess the economic performance, in terms of capital and whole lifecycle costs, of various carbon-saving measures for an office building based on output from the Tarbase project [12]. The results are designed to inform the understanding of drivers and barriers of carbon-saving refurbishments of existing non-domestic buildings.
Description of methodology Whole life cost (WLC) method In this market context, we consider relevant and significant a quantitative appraisal of whole life costs of energy efficient interventions suitable for reducing office building greenhouse gas emissions. Cost effectiveness is likely to be a significant criterion for corporate managers and property investors, so it is therefore essential to clarify the financial terms of office building retrofitting of energy efficient technology. We have focused on the built stock because given the low rate of turnover of the building stock: only 30% of the building stock is estimated to be replaced in 2050 [13]. In this context refurbishment of existing office buildings becomes a key action to diminish carbon dioxide emissions in the sector. WLC may be applied at the whole building, element or system level, through to the selection and specification of individual products or components. Most attention to the application of WLC has been on new-build construction, or is generic and unspecified, but the Tarbase project specifically deals with evaluating the cost and impact on carbon performance of retrofit work to existing building variants (i.e. simulation models of buildings that are indicative of parts of the building stock, see Jenkins et al [14]), for comparison with the ‘do nothing’ option. WLC forecasting is arguably gaining a wider application in green building design [15, 16], but its limitations are well known and detailed in literature [17]. Several critical aspects are relevant to the study; the reliability of information provided by suppliers is often discussed: Cole and Sterner (2000, p.372) point that “...one of the critical issues in green design is the use of innovative environmental materials and technologies for which experience and life-cycle performance information is, for the main part, completely speculative.” Energy costs can also be volatile, as current experience in international energy markets shows, making long term cost predictions difficult: the non-domestic electricity price (including Climate Change Levy) for medium sized consumers in the United Kingdom increased by about 97% between 2004 and 2008 from 3.84 to 7.54 p/kWh and non-domestic gas price for medium consumers increased by around 89% over the same period [18]. An application of WLC forecasting is to assess the financial performance of design options which are increasingly likely to include energy-saving interventions (Ashworth 2004). Horsley et al. (2003, p.350)
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recognise explicitly that “Life cycle costing is an intrinsic part of the decision to adopt or reject an energy efficiency strategy. The requirement is for a holistic assessment of the cost of adopting a particular energy efficiency measure or technology, against a reference case, which is based on either building regulations’ minimum acceptable standard, or a ‘do-nothing’ approach, depending on the nature of the strategy.” Simulated case-study building Using data from the Tarbase project, an office building case-study is adopted for this analysis, with characteristics shown in Table 1. The office has walls consisting of concrete panels with mineral fibre insulation, a flat, felt, insulated roof and double glazing, with U-values also in Table 1. Further details (including the carbon-saving intervention sets) can be found in Jenkins et al [14] and Jenkins et al [19]. Table 1 – Building characteristics of office variant Total height (m) Length (m) Breadth (m) Number of occupants Glazing ratio (% external wall) Wall construction U-value U-values Floor construction U-value 2 (W/m K) Roof construction U-value Glazing U-value Infiltration rate (ac/h) Ventilation rate (l/s/person) Lighting efficacy (lm/W)
14.8 40 25 286 40 0.65 0.27 0.87 2.75 1 10 70
The building was chosen with the office building stock in mind: the total floor area is similar to 20% of stock and the construction age 9% of the stock, using categories defined elsewhere [20]. This variant was then simulated for a London, urban climate based on a Test Reference Year for 2005 [21] for the described baseline scenario to estimate the energy consumption, and associated carbon emissions, that such a building might have. The simulation also used a detailed description of the office activity, namely small power, occupants and lighting. In a UK office, such factors are essential for adequately describing the energy use of the building, particularly as the internal heat gains generated from these three sources will have a profound effect on the heating and cooling requirements. This is further explored, and detailed, in the aforementioned references. Carbon-saving interventions With the above baseline established, for a 2005 climate, a series of future scenarios were defined to estimate the energy consumption of the building following energy-saving refurbishments. For simplicity, and ease of simulation, these refurbishments were described in intervention packages consisting of, at times, several technology changes. While this can limit the analysis of individual technologies it does show a step-by-step progression of reduced energy consumption as different packages are installed. The order of interventions were chosen using the classic engineering approach of reducing the demand and then supplying this demand (be it thermal or electric) through low-carbon solutions. The packages are applied cumulatively, so the described order of interventions will be important in both the energy and economic analyses. Table 2 summarises the intervention packages and Figure 1 shows the effect on the building carbon dioxide emissions. The technologies are grouped into six packages, as listed in the table and quantified in Figure 1. Carbon intensities of gas and electric are assumed at 0.19kgCO2/kWh and 0.52kgCO2/kWh respectively.
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Table 2 – Summary of intervention technologies and corresponding package number Intervention
Description
Personal Computers Monitors Copying/Printing/Faxing Server Lighting Climate change Fabric changes Glazing Condensing boiler Mechanical ventilation heat re covery Adaptive comfort Solar thermal panels Sola r photovoltaics Onsite w ind generation
Intervention no.
Slight improvement in PC "on" power draw (70W to 60W). PC goes into low power mode when not being used and switched off overnight and at weekends Radical technology change from CRT to cholesteric LCD (61W to 7W "on" power draw). Power management as above All copiers replaced with multifunction machine with lower power draw (1354W to 720W). Machine also performs all scanning/faxing and replaces printers reduced (from 96No. to 81) 8% of non-essential servers switched off T12 lighting replaced with LED lighting (70 to 150lm/W). 10% of lighting left on overnight rather than 50% External effect of assumed change in climate by 2030 External insulation (EPS) for walls; EPS replacing mineral wool in floor/roof; Infiltration rate reduced from 1ac/h to 0.5ac/h Triple-glazed, argon filled replacing conventional double glazing Replacement of "high efficiency" boiler with "condensing boiler" Heat wheel added to existing ventilation system, with heat recovery efficiency modelled every hour (based on climate and internal temperatures) Adaptation comfort used to control cooling setpoint (rather than static 23degC) Sized to meet 50% of the hot water demand (approx. output of 21,000kWh/yr) 27kW mono-crystalline panels (approx. output of 26,000kWh/yr) 10No. 1.5kW turbines on roof (approx. total output of 4100kWh/yr, with average urban wind speed)
1* 1* 1* 1* 1 2 2 2 2 3 3 4 5 6
*IT-related measures are zero-cost as they are assumed to occur through regular upgrades that would occur regardless of intervention advice (though choice may be different)
Figure 1 – Simulated carbon dioxide emissions of different intervention scenarios for office variant
Annual carbon dioxide emissions (kg/m2)
80 70 60 50 40 Elec
30
Gas
20 10 0 Baseline
1
2
3
4
5
6
Intervention package Prior to onsite generation (i.e. up to package 3), the interventions have reduced carbon emissions by 66%, though a large component of this saving is due to improved IT equipment and lighting improvements, i.e. relating to the internal activity rather than the building fabric or services. IT equipment tends to be a technology that is upgraded every few years for most offices, so promoting the purchase of energy-saving IT equipment over existing choices could be argued as being costneutral. Adding the onsite generation packages results in a total carbon saving of 72% compared to the original baseline, a modest improvement even for the relatively large systems modelled.
Economic analysis of intervention sets A full cost analysis of the described technologies requires, firstly, estimating the capital costs of the specific measures, including the installation and preliminary costs. This can then be compared to the operational energy costs over time in the whole life cycle cost analysis. The costs have been estimated by quantity surveyors Thomson Bethune of Edinburgh, using manufacturers’ data and standard methodologies for costing real building projects. Capital costs Table 3 shows the capital costs of the identified measures. This includes all installation costs, builders work and preliminaries – this is therefore the total capital cost that a business or organisation might have to pay for the measures as specified.
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Table 3 – Capital costs of individual measures for office variant Rate (£ Running Total (£) Description Unit Quantity per unit) Amount (£) 100 lux m² 460 49 22,540 Lighting 150 lux m² 120 63 7,560 Replacing existing 500 lux m² 3,420 216 738,720 fluorescent lighting with Builderswork inc. LED installation Preliminaries sum 1 7,035 7,035 TOTAL 775,855 2 5,504 11,008 Fabric and Boiler Cost of Installation nr Builderswork nr 2 200 400 Replace existing boiler Preliminaries sum 1 372 372 with condensing boiler TOTAL (2Nr 147kW boilers) 11,780 Cost of Installation m² 4,000 1 4,400 Draught strip all openings Builderswork inc. (reduce infiltration rate Preliminaries sum 1 292 292 from 1ac/h to 0.5ac/h) TOTAL 4,692 Cost of Installation m² 760 460 349,600 Replace double glazing Builderswork m² 760 50 38,000 with argon-filled triple Preliminaries sum 1 12,592 12,592 glazing TOTAL 400,192 Cost of Installation m² 1,154 80 92,320 150mm EPS insulation to Builderswork m² 1,154 inc. external face of wall with Preliminaries sum 1 22,278 22,278 13mm concrete render TOTAL 114,598 Installation m² 1,000 5 5,000 Replace mineral wool Cost ofBuilderswork m² 1,000 90 90,000 insulation in floor with Preliminaries sum 1 14,440 14,440 100mm EPS TOTAL 109,440 Cost of Installation m² 1,000 10 10,000 Replace mineral wool Builderswork m² 1,000 2 2,000 insulation in flat roof with Preliminaries sum 1 3,110 3,110 200mm EPS TOTAL 15,110 1 3,350 3,350 Heat recovery* Cost of Installation item Builderswork item 1 1,500 1,500 Preliminaries sum 1 1,460 1,460 TOTAL 6,310 1 115,000 115,000 Solar photovoltaic Cost of Installation item Builderswork item 1 1,500 1,500 system Preliminaries sum 1 850 850 TOTAL 117,350 10 6,500 65,000 Wind turbines Cost of Installation Nr Builderswork Nr 10 inc. Preliminaries sum 1 1,500 1,500 TOTAL 66,500 1 69,000 69,000 Solar thermal panels Cost of Installation item Builderswork item 1 2,000 2,000 Preliminaries sum 1 1,500 1,500 TOTAL 72,500 1,694,327 FINAL TOTAL (£) One of the issues of costing such measures, particularly for future scenarios (where the Tarbase project is using 2030 as a future timeline), is that capital costs of immature technologies are likely to change dramatically as they achieve higher market penetrations. This is likely to be true for LED lighting, where current costs have been used in Table 3. However, if the assumption is made that LED lighting will become (at least) as competitively priced as current best-practice office lighting (such as T5 fluorescent lighting), the £775,855 figure in Table 3 for lighting is calculated as dropping to £255,400, giving a total cost of all refurbishments of £1,173,880. This lower total will be used for the subsequent WLC analysis. Whole-life cycle cost estimates Table 4 presents the results of a whole life cycle cost analysis of all six intervention sets, using the metric of Net Present Value (NPV).
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Table 4 – Net Present Value of intervention sets
Difference in Difference in NPV from previous Intervention Cumulative Cumulative NPV from no. capital cost (£) NPV (£) baseline (£) package (£) Base 1 2 3 4 5 6 0
-1,370,814
-
-
255,400
-1,308,579
62,235.00
62, 235.00
-352,325.00
911,212
-1,660,904
-290,090.00
917,522
-1,644,122
-273,308.00
16, 781.00
990,022
-1,696,577
-325,763.00
-52,454.00
1, 107,372
-1,763,351
-392,536.00
-66,774.00
1, 173,872
-1,820,900
-450,086.00
-57,550.00
The main assumptions used in the analysis are: • All WLC estimates are relative to the base case. The lifetime costs associated with this base case assumes carbon saving technologies have not been implemented • Existing boilers will need to be replaced within 10 years of the project start • Windows are to be replaced within 20 years of the project start •
Existing windows will be timber framed and will require re-painting on a regular basis
•
Existing boilers are to be serviced on an annual basis. This cost is expected to be greater than the cost of maintaining the new condensing boilers For the base case, it is assumed that the existing lighting system will be replaced with T5 fluorescent lighting within 20 years of the project start. The lighting interventions for the refurbishment scenarios assume LED lights (at 150lm/W) being cost-competitive with T5 fluorescent lights (lumen for lumen) It is assumed that fluorescent tubes and starters are replaced in every light fitting at 2 year intervals Energy costs have been fixed at current prices (dated April 2009) Discount rate is assumed at 3.5% per annum Inflation rate is assumed at an average of 2% per annum over a thirty year time period (in line with Bank of England targets) Energy price volatility over time is not accounted for outside the above assumptions All costs are exclusive of VAT
•
• • • • • •
It emerges that the only intervention package which provides a financial case over the 30 year duration period of our WLC analysis is intervention package 1, when compared to the original baseline. This is consistent with the idea that modest carbon savings can be made in a cost-effective way, but larger-scale carbon reductions have increasing capital costs that might become difficult to justify for many businesses and organisations in terms of financial payback through energy bills. It is useful to compare this scale of cost with other types of renovations that office buildings might experience. If we take package 4, with all the technologies preceding it, the total refurbishment cost equates to £229/m2 total floor area (increasing to £293/m2 for package 6). Renovations of buildings can take many forms, and so costs will naturally vary considerably. However Rawlinson and Wilkes [22] give figures of £300-825/m2 (using gross, rather than total, internal floor area) for a minor refurbishment, with a “category A” major refurbishment costing £1,450-2,100/m2. While such refurbishments include a range of improvements not considered in the Tarbase analysis (such as carpets/flooring, stairwell and other aesthetic improvements), these figures do provide an indication as to the expected cost of making a major change to a building. It also gives credence to the idea, touched upon in the Introduction, that carbon-saving refurbishments might be more successfully promoted if other, non-energy, benefits were highlighted for carrying out a major refurbishment; very large sums of money are already spent on building renovations that are not expected to pay back through improved “building performance”, but rather have added value to the image and running of that particular organisation.
Discussion and context with qualitative study In the current economic crisis, it is plausible to think that businesses might have a limited availability of finances to spend on paying a premium for a rented building. Organisational slack, in terms of
119
availability of funds and time of employees and managers, was positively related to green innovations [23, 24]; therefore in a time of diminished profits and shrinking organizations it is plausible to assume that this might hinder the progress towards more energy efficient buildings. This was also confirmed by two surveys: one found a limited availability of corporate property executives for paying a premium for sustainable rented space [8] and the other [25] found that the majority of small to medium enterprises (SMEs) surveyed don’t have funds (62%) or time (61%) to invest in energy efficiency. On the basis of the limited contribution of energy costs on overall business costs, it is certainly possible that companies might refrain from actively seeking an energy efficient building if the rental rates are higher than in more traditional buildings. Conversely, there might be an expectation of rapidly rising energy costs, which would rest on the evidence of a long term trend: between the year 1995 and the year 2008 the price of electricity rose approximately 84% [26]. On a shorter term, the increase between 2004 and 2008 was 97% [26]. This expectation is reasonable and was confirmed by the Npower [25] survey of British SMEs and major energy users (MEUs) which reports that the majority of the sample, 300 British businesses surveyed, expected energy prices to increase. Businesses could therefore be more enticed into achieving energy savings because of this expected energy price increase. Nevertheless, the extent of this price increase is uncertain and energy forecasts have often been considered deficient [27, 28], providing information of little use for a reliable WLC analysis. As a result of the combination of these pressures on businesses we could expect to see the effort to curb energy consumption resting mainly on low-cost strategies, such as behavioural change and optimisation of facilities. This seems to be confirmed by the Npower survey. Despite these general economic arguments appearing reasonable, other intangible benefits in choosing a sustainable office should not be underestimated, at least for large and visible businesses. In a survey carried out in 2007 for the Tarbase project [29] it was found that a further significant factor influencing positively companies’ interest in sustainability was the reputational gain deriving from adopting sustainable business policies. This is not in itself surprising; the presence of increased business opportunities for those engaged in Corporate Social Responsibility (CSR) and Sustainability has been an object of research for many years [30]. Research has made clear that not all companies are equally exposed to such benefits (and costs): close to consumers companies [31, 32] and larger businesses [30, 33-35] show to be particularly affected positively or negatively by reputational gains or losses. The Tarbase survey of office market stakeholders [29] presented an analysis of the factors influencing business decision-making with regards to the pursuit of energy efficient office space. In July 2007 twenty-one interviewees were surveyed through sixteen semi-structured interviews held in London, Glasgow and Edinburgh. The interviewees were: ten surveyors (eight based in London and two in Glasgow) and two technical consultants based in London (one the head of the facilities management department of an international consultancy firm). The remaining respondents were members of businesses and office occupiers based in Glasgow, with the exception of one respondent based in Edinburgh. Office occupier respondents were: an operations and property manager, a CSR officer, two environmental officers, three facility managers and a facility manager assistant. The interviews were chiefly conducted with letting surveyors because of their privileged position in the market which mediates between the demand and the offer of office space. While the full extent of the theoretical background and the findings of the survey are presented elsewhere [29] we wish to report here some of the main findings. Firstly, all the subjects surveyed showed an awareness and sensitivity to energy efficiency. There was also a broad consensus about the general awareness of market actors and a growing demand of energy efficiency was reported. Nevertheless interviewees reported a lack of willingness to pay more for energy efficient rented offices: this finding is coherent with the 2009 survey of Jones Lang LaSalle [8]. Despite this, interviewees pointed to the growing importance of reputational drives which would be influencing investors and large occupiers towards an increased pursuit of energy efficient office space. Reputational benefits would influence occupiers positively, attracting both customers and investors. Furthermore, it was found that employees in some cases had promoted their own energy saving behavioural initiatives. This is consistent with the widespread pro-environmental attitudes which surveys have repeatedly found within the British public [36, 37]. This might be hinting to the reason why it has been found in research that “corporate greening” increases organizational commitment [38] and attractiveness of skilled jobseekers [39, 40]: an issue that was also reported by respondents in the Tarbase survey of office market stakeholders.
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Tarbase survey respondents considered investors as being under pressure from their shareholders, who might request a CSR agenda for the investing institution and who also might see sustainable buildings as better value investment in the long term: these issues also emerged in British [9, 41] American [11] and Australian [10] surveys. Despite the combining forces on investors and occupiers conducive to increased energy efficient offices, the Tarbase survey found that occupiers lack the willingness to spend more for sustainable offices, and this fact might have been even reinforced by the 2008-2009 economic crisis. If this is indeed the case, it could be difficult for investors to give in to the pressures of shareholders and stakeholders. Nevertheless, recent research on the US building stock [42-45] has found that energy efficient offices return a rental premium in comparison with non-energy efficient buildings. It is difficult to say if the British market will follow, or already is following, the American trends. Certainly the scale of the investment required to abate emissions in office buildings might be regarded as significant for owner-occupiers which are dealing with the crisis. It is perhaps more likely that investor-owners will be the actors leading the change, possibly investing in energy efficient technology when they have to refurbish the buildings of their portfolios. The necessary refurbishment might be an opportunity to reduce the costs of installation and it might generate a total cost which is generated mainly by the difference between current conventional technologies, which during a refurbishment need to be installed anyway, and energy efficient solutions. This idea is supported by the estimations in section on Economic Analysis of Intervention Sets: a relatively ambitious carbon-saving refurbishment package might be, from a capital cost perspective, within the range that a company might expect to pay for a renovation. The value of that renovation to the company then becomes both about reducing energy bills and also about the non-energy benefits that the organisation might realise.
Conclusions The need for large-scale refurbishments to reduce carbon emissions in the UK non-domestic building stock is clear. Conventional approaches to promote the described technologies have tended to rely on payback mechanisms, i.e. the length of time that it might take for a specific measure to repay the capital cost expenditure. This study has used an individual case-study building to calculate capital and whole-life cycle costs to explore how these modelled results compare with qualitative surveys of building professionals, and their motivations for installing such measures. It is calculated that most measures, beyond those associated with lowering the small power and lighting electrical demand, are not justified on purely economic grounds. However, this approach (and similar, conventional attitudes to the value of green refurbishments) misses several important points. Firstly, to achieve challenging targets (such as 50% or greater) it is often necessary to look at relatively immature technologies that, with a high capital cost, are unlikely to pay for themselves within a period that is attractive to a potential purchaser. Secondly, even if attractive payback periods are predicted (either due to mass, and cheap, production of the measure or grant assistance) it is not necessarily true that this will make the product a “no-brainer” for all organisations: energy bills for many organisations are relatively small compared to other running and service costs. For such an organisation, the decision might therefore be “should we spend a large amount of money, upfront, to make a small bill slightly smaller?”. While green mortgages and other grant/loan schemes might be designed to improve the response to this question (and thus reduce the large cost that will appear on the balance sheet that year if the measures are purchased), there is also the fact that organisations will, and do, spend very large sums on improving their buildings through “conventional” renovations. If the added value of green renovations, which would appear from this study to be within a similar cost range as conventional renovations (adding, at the most, £300/m2 to the total costs), could be further highlighted and investigated, it is possible that a large market for such measures will emerge. If owners are willing to carry out renovations on their buildings accepting a relatively small additional cost, £300/ m2 or less, then perhaps the existing refurbishment market can be exploited to increase the installation of carbon-saving technologies in the non-domestic sector. For other organisations, particularly those looking at installing smaller-scale measures, the use of payback metrics might still be relevant, such as an organisation with a large energy bill from manufacturing or processing activities. However, the full range of drivers that affect the decision-
121
makers in an organisation should be addressed to increase the market share (and, indeed, create new markets) of large-scale green retrofits. In this context there is space for non-financial policy interventions, which might be of particular value at a time of constrained public budget. As suggested elsewhere [29] the intangible reputational benefit could be made more salient and therefore efficacious in driving change. Currently the main policy instrument which exploits such a benefit is the introduction of Energy Performance Certificates (EPCs) which are mandatorily provided during the purchase or a lease of a building. The natural progression of this policy should be to demand visibly displayed EPCs in all non-domestic buildings. However, a clear opportunity for emphasising the visibility of energy-saving buildings would be the mandatory use of Display Energy Certificates in non-domestic buildings. With the use of real energy data, this would provide a clearer picture to all stakeholders in a building as to the effectiveness of the technologies and energy management in the building, as well as removing the reliance on the model predictions of EPCs (with their large uncertainties). The government ‘Carbon Reduction Commitment’ (CRC) programme, starting in 2010 [2], will provide both an economic incentive for companies as well as making public a ranking of the performance in carbon emissions reduction of major energy users in non energy intensive industries, which will possibly impact on the reputation of businesses. Other metrics representing the carbon emissions of a company could be formulated (for comparing with similar organisations), reduced to a performance indicator that is both intuitive and comprehensible. Such metrics could be mandatorily displayed on the web site and on the marketing material of a company. The reputational consequence of this could result in a more concerted effort from organisations to reduce not only their buildings’ emissions but also their general carbon footprint.
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The importance and the impact of economic, organizational, cultural and social goals of companies and institutions for commercial buildings Martin Pongratz, Thorsten Speer M.O.O.CON
Abstract In order to fulfil their missions in an environment of constantly changing markets, companies, organizations or public institutions need to adapt and optimize their organizational structures and work processes regularly. Such adaptations are triggered and organized by the organization’s executive management functions. For tackling these tasks executives use to devise strategies, set up and rank goals and strive for their effective implementation. Whilst the main goals of organizations, by definition, focus on core business issues, managers nevertheless must also define goals for activities and issues within the organization that are only indirectly linked to the core business. For example goals related to facilities, i.e. facility management issues as for instance energy efficiency and sustainability, are issues that contribute only indirectly to the organization’s success. To which extent company managers or executives of organizations in general focus on goals that have to do with facilities, facility management, energy efficiency etc.? Do executive managers acknowledge the impact such matters have on their organizations? How would they prioritize such goals? These were questions the M.O.O.CON team (formerly bene Consulting), a consultancy practice that is advising organizations in space planning and building development projects, wanted to investigate in more detail. For this purpose a market research study was set up wherein directors and managers of 150 companies and institutions from both Germany and Austria were interviewed about the organizational goals with regard to facilities and facility management aspects. The survey shows that although economic goals are clearly ranked higher than other goal categories, managers are quite aware of the necessity to deal with green and sustainable building measures.
1. Introduction Experience shows that in their efforts to fulfil their missions corporate companies and public institutions pursue diverse strategies which define very distinct sets of goals the organizations are set to achieve. Apart from the main goals that are directly related to the core business and the core activities of an organization, a well managed organization must, in addition to that, strive for the implementation of goals that relate to issues that have a less apparent ,link to the core business. All objectives linked to facilities and facilities management etc. are such goals with indirect effects on the core business. How well are the facilities moulded to the genuine needs of the functions the organization’s staff are executing? To which extent facility operating cost are taken into consideration when taking core activity decisions? How aware are executive managers of the effects their facilities and its management do have on core business? As a company specializing in the organizational planning and brief making of building projects, M.O.O.CON wanted to know more about the attitudes executive managers would have towards these issues. Indeed, as a “facility usage” specialist M.O.O.CON has gathered project experience that shows
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that timely integration and coordination of facilities’ issues into the overall core business goals definition process makes not only sense but also may contribute to higher staff performance and a decrease of overhead costs. How aware executives would be of such phenomena and opportunities? M.O.O.CON’s idea was to ask a significant quantity of general managers of different types of organizations, what kind of objectives they would consider regarding their facilities, whether these objectives had changed with the general shift in the global economy and how they would weigh the importance of several goal categories and their impact on the core activity. For this purpose the Gallup market research institute was assigned to roll out a survey wherein directors and general managers of 150 companies and institutions with more than 50 staff working in office functions were interviewed.
2. Market survey’s methodology The poll was rolled out in April/May 2009. A standard questionnaire for a telephone poll was worked out and prior to engaging into the interview the professional interviewers were instructed to check with the help of some key questions whether the interview partner belonged to the target group. The sample consists of 75 organizations located in Germany and 75 organizations from Austria. Companies and organizations were randomly chosen, however, they were only retained for interviews if they had more than 50 staff in office functions. Also, the aim was to create two more or less even subgroups of organizations with 50-250 employees and organizations employing more than 250 people: the final sample consisted of 46% interviewed organizations employing up to 250 staff. 54% were companies with more than 250 employees. Furthermore, the survey’s aim was to focus on office facilities. Therefore only companies using a significant amount of office space were chosenfor the poll: 60% of the organizations questioned were organizations employing between 50-150 office staff and 40% were organizations with more than 150 people in office functions. 72% of the sample occupied a facility entirely by their own organization whereas 28% of the organizations shared office areas within a greater facility with some other organizations. The sample consisted of a fair mix of different industries: Finance Services (28%), Industrial products (23%), public services & institutions (17%), retail & trade (11%), Training & education (6%), other services (15%). In preparation of the interviews a list of possible organizational goals with regard to office facilities was compiled by M.O.O.CON consultants. The goals were gathered from project experiences and had been raised by a variety of clients in different projects. In order to allow a more differentiated ranking, goals were clustered into 4 chapters, i.e. “economic”, “organizational”, “social” and “cultural” goals. The clustering process was inspired by the seven basic aspects that determine an organization according to Glasl/Lievegoed1: The goals defined as “cultural” goals are goals that relate to the aspects described by Glasl/Lievegoed as “identity related” and “policy/strategy related”. The goals defined as “organizational” relate to the organizational aspects Glasl/Lievegoed declare as “structural related”, “single function and task related” and “process related”. The goals defined as “social” are those that relate to Glasl/Lievegoed’s aspects described as “people,group and relationship related”. Eventually, the goals clustered among the chapter “economic” are those that relate to Glasl/Lievegoed’s aspect “physical and material resources related”. At the interview each manager was first introduced to each chapter and then asked to rate the goal between 1 and 4 (1= very important ; 2= rather unimportant; 3= rather not important; 4: no importance at all). At the end of the interview the managers were asked to weigh the importance of the four different goal categories themselves by giving percentage quotes.
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3. Results in a nutshell The results of the survey show that a significant majority of company managers are quite clearly aware of office facilities being cost factors. It also became clear that managers indeed understand that office facilities have an influence on core activities through a variety of aspects. Moreover, it became apparent that the general sensitivity for ecological issues and their connection with commercial facilities has reached the executive management levels: In the overall ranking of office facility goals, three of the top five goals had a direct connection with environmental issues. Furthermore, the results demonstrate that organizational leaders see clearly the link between corporate buildings and the corporate responsibility for the environment and the society as a whole. Eventually, a significant fraction understands that office facilities can improve working culture and work efficiency. However, only a limited number of organizations see and understand the true potential of using their premises as a tool for improving brand awareness, corporate culture or the general image of their organization.
4. Results in more detail and some conclusions 4.1. The sensitivity for operating costs of facilities has clearly increased Objectives such as reducing a facility’s energy costs and operating costs as a whole were considered by 92% resp. 91% of all interviewed managers to be “very important” or “rather important” (henceforth written as very/rather important). The cluster of all objectives focusing on building operating expenditures (OPEX) in more general terms was still considered by 89,3 % of the managers as very/ rather important, whereas the focus on capital expenditure (CAPEX) was considered by 64,8% of managers as very/rather important. In 2005, in a comparable study, it had been rather the other way round: operational costs had been clearly ranked lower, whereas investment and capital expenditure had been considered most important. Moreover, the importance of considering a premises and its cost over its whole lifecycle is accepted by 69% of all managers. All this indicates that the sensitivity for acknowledging the relative importance of OPEX versus CAPEX over the whole lifecycle of a building is increasing. An clear majority of executive managers are aware that operating costs represent a considerable overhead that needs to be monitored and managed. Viewed from the industries’ angle, retail & trade related businesses seen to be particularly aware of the operating cost issue (average mark of all indudtries together: 1,51 ; retail mark: 1,24). This is probably due to the fact that retail is a very cost conscious business that moreover intensely deals with premises and real estate issues within the frame of its core business activities. 4.2. The office facility as an instrument for increasing the organization’s productivity 82% of the interviewed managers state that the goal of improving communication and team culture among staff by developing satisfactory layouts and infrastructure, is considered to be very/rather important. 77% declare that the appropriate transposition of organizational units into the floor footprints would be very/rather important, too. This shows that a clear majority of executive management is aware that work flow as well as work and communication processes within the office area depend on the spatial frame, i.e. its geometry, footprint and design. A well designed infrastructure helps the organization to communicate, i.e. to perform, better. However, it also shows that a lot of companies and premises have deficits in that respect, because otherwise managers would not attribute such importance to the issue and would not declare it to be an important goal for improvement in the future. In this context, it makes sense that, also, approximately half of the persons interviewed that attribute importance to spatial design and productivity, do envisage to raise their staffs productivity through changing the premises: this can be interpreted as the consequence of the management’s analysis that better communication among staff would need better and adequate spatial infrastructure. 4.3. Executives readiness to assume social responsibility The poll shows that 82% of the interviewed managers consider it very/rather important to assume social responsibility. They accept the concept that choosing premises that would be less energy consuming, less polluting with a lower ecological footprint etc. would help global efforts of mitigating
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global warming etc. and that this decision of contributing or not lies with the executive taking this decision. Hence, executives are conscious of the fact that there is a link between improving environmental quality and choosing the right office premises. Whether this attitude translates into concrete decisions, however, remains to be seen. A significant number of decision makers say in the interviews that they would consider changing premises. As a consequence one could interprete this as a certain disposition of executives to opt for more energy saving and sustainable premises concepts. However, it is not clear whether such a “preparedness” would actually materialize: On the one hand the implementation of such an increased sensitivity depends on the availability of adequate facilities on the facilities’ market that would fulfil the expectation. In fact, executive choices can only be made in favour of a more socially responsible and environmentally friendly direction, if the market actually offers such facility solutions. On the other hand, chapter 4.6 points out that economic criteria have still an important weight and may outweigh the “sympathy” for a socially more responsible solution. 4.4. Limited awareness of cultural impact facilities can produce Only 50,2 % of the interviewed persons said that they would use their premises to strengthen the corporate image or increase brand awareness. Undoubtedly, facilities bear the potential of “conveying” messages, moods or statements into the society. A very simple message may be a visible positioning of some brand signage. A more comprehensive and complex cultural statement might be a building of a particularly outstanding iconic landmark design that people immediately would associate with the company name or brand. But even without being a landmark, buildings can nevertheless quite clearly convey a philosophy or a value statement in more subtler ways. Some clients of M.O.O.CON such as the Swiss Re that realized 3, a new headquarters project in Munich or for the Helvetia Insurance Group for example, communicate through their facilities both a spirit of quality consciousness and a consequent striving for stable, long lasting sustainable solutions. By the very fact that their facilities have been designed and built with a product and building philosophy that followed a policy of precisely choosing solid, long lasting, high quality, sustainable building and fit-out solutions, the Helvetia Group wants to demonstrate that it strives –in any issue- to be a partner that believes in solidity, trust, high quality and long lasting business relations. The building process and its resulting facility is so to say “staged” as an example and a proof for the business policy and values the Helvetia Group stands for. The building, therefore, becomes and really acts as a “value and brand messenger” conveying the corporate brand message to any visitor or passerby. Companies such as Helvetia are convinced of the positive impact this “built brand & value message policy” achieves. They are convinced that a passerby or a visitor has the capacity of “sensing” and perceiving the spirit such a building “radiates” if a gifted architect is given the opportunity to create a building embodying the corporate values via an adequate architectural and artistic design “language”. As the poll shows, 50,2% of the persons interviewed may tend to share and follow these exemplary concepts explained with regard to the Helvetia case. 49,8% however do not share this opinion. Hence, the potential of seeing in buildings tools that would strengthen the organizations brand or image is not as wide spread yet, as the aspects developed in the previous chapters. Also, only a minority of f the interviewed persons did actually pronounce a clear statement that such a goal would be “very important”. Yet, especially seen from the environmental and energy saving perspective, this option of using the organization’s premises as a policy statement bears some potential: By choosing or creating one’s premises as a building that is visibly more environment-friendly than standard buildings and by communicating it (e.g. Leeds or DGNB certificates visibly displayed; mentioning it in public relation occasions, etc.), an organization can obviously support and spin its image and marketing efforts in a certain direction that may be beneficial for for the core business… 4.5. Strong awareness that commercial buildings and environmental goals are interlinked In the list of the goals related to their facilities, managers consider unanimously environmental topics as being very important. 88% of all persons interviewed replied that it would be a very/rather important goal to care for minimization of CO2 emissions during the design and implementation process of new office buildings. Also, 3 out of the 5 top ranked goals of the poll are goals which have an environmental impact (i.e. minimization of energy consumption: 92%; minimization of operating cost: 91%; minimization of CO2 emissions: 88%). Undoubtedly, this is a sign that managers have become aware that corporate facilities and other commercial buildings play a substantial part in environmental issues and that changing conditions of operating and creating commercial facilities would clearly contribute to reducing global energy consumption and pollution. What remains to be found out is to
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which extent this awareness would be reflected in decisions that would indeed produce commercial buildings with a more environmentally friendly profile.
4.6. Non-economic goals have a significant importance for decision makers As explained further above the interviewed managers weighed various goals that had been structured for the interview in different chapters. In one chapter, the “economic" goals chapter, all economic goals were clustered which were interlinked with office buildings. In another chapter all goals that were focusing on organizational issues were grouped and eventually there were two more chapters where social and cultural goals had been listed. At the end of the interview the executives were asked how they would weigh these 4 chapters, amongst one another and give them a percentage they felt would correspond to the weight this chapter would have in the overall decision making process. The interviewed executives ranked them as follows: 1. Economic goals: 39% 2 : 2. Social goals: 21,5% 1 : 3. Organizational goals: 22% 1 : 4. Cultural goals: 17,5% 1
Obviously, decision makers clearly prioritize the economic aspects of facilities. This means that e.g. the optimization of energy consumption within commercial facilities is considered by executives clearly as the prime important and decisive criteria for their premises’ decisions. Indeed, economic goals are approximately double as important as the goals of the other categories. However, it is remarkable that the other goal categories still have significant weighting factors. According to the poll the weight relations are roughly 2:1:1:1. They could have been easily 3:1:1:1 or 4:1:1:1 but they are not. Actually when viewed together, the sum of organizational, cultural and social goals even outweigh purely economic goals. This means that economic considerations alone will not automatically prevail under any circumstances. Depending on the mix of goals a company would have in the different categories, a strategic corporate facility policy can indeed be determined rather by more organizational, cultural or social drivers than only economic ones. Hence, the organizational, cultural and social facility goals do have a significant influence on a buildings’ quality and physical characteristics.
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5. Conclusion: Necessity to refine real estate decision making processes The results of the survey show that decision makers are aware that commercial facilities are instruments that may have positive impacts both on the cost and on the asset side of their core business. The survey indicates that an important part of executives have developed a sensitivity that decisions with regard to facilities have a direct influence on their organizations work processes and the core business. Also, it can be seen that although purely economic arguments have an important influence on decision making they do not automatically prevail. What lacks, as a next step, is a clear-cut vision of how such awareness can be systematically transposed into real decision making and implementation of such more comprehensive and integrated facility solutions. The question remains how executive management can proceed in order to successfully create corporate facilities solutions that would meet their expectations for real and not just on paper. For this purpose, M.O.O.CON has elaborated a strategic decision making procedure that systematically compiles first the catalogue of corporate business goals. All business goals that can be supported by architectural and space organizational solutions are systematically transcribed into a catalogue of corporate infrastructural goals. With these goals in mind, all architects and designer briefs for the premises creation or search process are formulated. A systematic multi-level monitoring and reporting procedure ensures that any technical engineering solution at the most detailed level still stays in line with the original strategic business guidelines. Hence, this procedure, which integrates the DGNB certifying procedure as a by-product, allows the management of the executive level to pursue their goals up to the final fit-out and operation aspects of the new facility.
6. Main results in graphical form (German)
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References [1] [2] [3]
Friedrich Glasl/ Bernard Lievegoed. Dynamische Unternehmensentwicklung – Grundlagen für nachhaltiges Management, 3.,überarbeitete und erweiterte Auflage, Haupt-Verlag/Freies Geistesleben (D), 2004. ISBN 3-258-06698-1. Friedrich Glasl. Professionelle Prozessberatung, Haupt-Verlag (D), 2005. Sebastiano Brandolini (editor). Helvetia – Costruire Building Bauen, Helvetia (I), via G.B.Cassinis 21, 20139 Milano, 2007.
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How to overcome the socio-economic obstacles for efficient energy use in Smart buildings – and opportunities to save energy through efficient interoperability with the Smart grid Volker Dragon Siemens Switzerland Ltd.
Abstract This outline describes how a successfully implemented Smart grid / Smart Building technology supported by regulators, legislators, vendors, utilities, and academia can benefit the entire society in terms of making efficient use of primary energy and environmental protection. We propose the thesis that Smart grid / Smart Building technology could prove to be a cost-effective infrastructure investment if the system is designed to maximize energy saving as well as energy efficiency in a close co-operation with all stakeholders involved. In his speech Andreas Schierenbeck will outline how rapid market penetration for Smart grid / Smart building technology can be created if consumers are aware of how the Smart grid / Smart building can provide benefits to them in each of their key value areas such as improved reliability, security, economics, efficiency, environmental friendliness, and safety and how the EU Parliament as well as country-specific regulators and legislators can help to encourage Smart grid / Smart building projects trough a well-coordinated financing and incentive framework In her speech and showcase Cathy Yang will outline how she and her management team will make TAIPEI 101 to be a paragon in the energy-saving global architecture industry and how she plans to overcome the economic and social obstacles to arouse people’s awareness in our environment. Taipei 101 is planning to invest approximately US$2 million and make more than 100 modifications to turn itself into the world’s tallest environmentally friendly building within 18 months. The Taipei tower is the second tallest building in the world after the Burj Kalifa skyscraper in the United Arab Emirates. While this session focuses on discernable or suspected movements, we also recognize that other influences, more sudden and less predictable, have also had significant impacts on energy use and efficiency in the past. "Out of the box" thinkers who come to this session will be encouraged to remind the rest of us of past surprises and to expect future ones. Cities consume 75% of global energy The development of new cities and the re-development of existing cities are taking place at a moment when environmental sustainability is a major consideration for national and local governments. However cities have become the worst offenders when it comes to greenhouse gas emissions. Today cities cover 1% of the earth's surface where over 50% of global population reside and work. The result is cities consume 75% of global energy and produce 80% of GHG emissions. Around 40% of this energy is consumed in Buildings which account for in 21% of GHG emissions. Big Cities pay attention to ensuring energy efficiency in buildings While cars have had to meet increasingly strict fuel efficiency standards, buildings for the most part have gotten off easy. Surprisingly little attention has been paid to ensuring energy efficiency in buildings, despite the tremendous impact buildings have on energy costs and the environment. That oversight is starting to be addressed. A combination of higher energy prices, skyrocketing demand for electricity and deepening environmental concerns has pushed cities to a tipping point with regard to energy efficiency in buildings. Simply put, business as usual threatens the continued prosperity of cities all over the world. The economics are powerful, promising quick paybacks on investments for building developers and their tenants. The economic case is equally strong for governments, which are furiously building power
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plants in an attempt to keep up with surging demand from new buildings and their often inefficient Building automation systems and lighting. The environmental case is every bit as strong as the economic one. The authoritative Intergovernmental Panel on Climate Change in its most recent report noted: It is often more cost-effective to invest in end-use energy-efficiency improvement than in increasing energy supply to satisfy demand for energy services. Efficiency improvement has a positive affect on energy security, local and regional air pollution abatement and employment. [1] Greater efficiency means consumers can enjoy the same level of comfort but use less energy. And when it comes to efficiency, improvements in buildings offer the quickest and most cost-effective way to reduce energy use and greenhouse gas emissions. Four of the five most cost-effective measures taken to reduce greenhouse-gas emissions involve building efficiency. The McKinsey Global Institute, which has studied the issue on a worldwide basis, estimates that four of the five most cost-effective measures taken to reduce greenhouse-gas emissions involve building efficiency. The measures are building insulation, lighting systems, air conditioning and water heating and cooling. For instance the single biggest possible lever for CO2 reduction in London is a basic one - better insulation. This on its own could take 4.5 Mt, or 10%, out of the city’s annual carbon output by 2025. It could also save the investors about €150m per year in energy costs net of investment by 2025. Measures relating to more efficient heating of buildings, such as condensing boilers, the recovery of heat and an optimization of controls, could add another 2.7 Mt of reductions, saving almost €400m for the investors by 2025. Similarly, energy-efficient lighting could eliminate 1.4 Mt per year, and save money for the investors (around €170m annually by 2025). Replacing old appliances with more energy-efficient ones in homes and offices could cut a further 1.3 Mt of CO2 emissions Incredibly, these measures result in net savings for building owners and their tenants, because their cost is so cheap compared to the savings [2]. Turn Buildings into a source of energy Building sustainable buildings and making old ones energy efficient alone is not going to solve problems. The impulse for building energy efficiency is not only about turning down the air condition or turning off the lights - it is about doing more with less. A major part of the solution is Smart Building Technology. This is one of the quickest and cheapest ways to turn Buildings into a source of energy. The technology integrates and optimizes the physical and digital infrastructures of commercial used buildings and groups of buildings. This enables the facility to react on price signals from the grid and shift or reduces energy consumption in high tariff times. More over they are used as storage for electrical energy and generate electricity for own usage and act as electricity provider to the grid. Commissioned Smart Buildings that work properly will be able to take advantage of Smart Grid infrastructure. To accomplish energy savings, building technologies must function well and be controllable in total. This means interoperability of the Smart Grid with all building technology systems (HVAC, lighting, electronic security fire detection and related metering) via a central building management function is imperative, because energy management systems in buildings will have to become autonomous systems able to respond to economic signals from the grid, including predictions about future prices. Furthermore in the future buildings will have a mix of distributed energy resources (e.g. wind, solar) as well as energy storage technologies (e. g. thermal, hydrogen, E-cars). This can arguably result in 20% efficiency gains - for each renewable energy source - without requiring new technology. Furthermore this is the first step towards net zero energy buildings. Investment and motivation Besides the governmental intention of energy efficiency in buildings economic incentives must be great enough to spur investment because currently there is low incentive for investment in smart building technology:
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1 2 3 4 5 6 7 8 9 10 11 12
Investors do not always have interest in energy efficiency buildings Architects focus normally on aesthetic and less on energy efficiency General contractors are not responsible for the energy consumption in the building Planner have little motivation to develop energy efficiency buildings Owner / Operator of commercial buildings simply pass the energy costs to the tenants Tenants have little motivation to invest in the improvement of energy efficiency of the building Owners invest, but the tenants benefit Rental premises with lower utility costs cannot command a higher rental rate Current utility tariff offers little motivation to save energy. Many processes in the buildings are not based on actual demands Economic considerations are not part of the HVAC control algorithms Technical and economic benefits do not automatically lead to maximum utilization and rational approach
The Role of Government In its Report “Energy Efficiency in Buildings the World Business Council on Sustainable Development (WBCSD) postulate: Appropriate policies and regulations are essential to achieve market changes. Climate change was described as “the greatest and widest ranging market failure ever seen” by Sir Nicholas Stern in his 2006 review for the UK government. He concluded that several types of interventions by governments are necessary to correct this market failure: 1 • Establishing a carbon price, through tax, trading or regulation 2 • Technology policy to support low-carbon innovation 3 • Removal of barriers to behavioral change, for example through information and standard setting. Businesses in the building industry need a supportive policy and regulatory framework to achieve dramatic improvements in energy efficiency. This is supported by the project’s research findings on industry leadership, which reveal that many building industry professionals only adopt new practices if they are required by regulation (see figure below.)
Governments need to concentrate on the most efficient and cost-effective approaches. Research for the UNEP Sustainable Buildings and Construction Initiative (SBCI) found that the most effective instruments achieve net savings for society and that packages of measures combining different elements are desirable. The study identified policies that were both successful in reducing emissions
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and cost-effective. Table 1 shows the most successful instruments in each of four categories. Governments in the countries covered by this project have introduced building codes and other relevant policies, as Table below illustrates [3].
But more needs to be done to encourage improved energy performance. It is not the role of this paper to define policy details but to identify key areas where policy initiatives can help influence holistic design, financial decision-making and behavior. Conclusion As we can see, efficient use of energy in commercial buildings – and opportunities to save energy through efficient technologies and practices – are influenced by many trends both within and outside the realm of either the buildings sector. We propose the thesis that Smart Grid / Smart Building technology could prove to be a cost-effective infrastructure investment for utilities as well as building owners only if the systems are designed to maximize energy saving as well as energy efficiency in a close co-operation because electric energy loads in buildings represent the most significant potential to maximize energy savings with the Smart Grid. Especially if different energy sources become well balanced and the building owners are able to trade with the energy generated by their own. More over as building automation systems (BAS) that control heat, air conditioning, lighting and other building systems get smarter, they're converging with traditional IT infrastructures. Emerging standards are enabling data sharing between building systems as well as with other business applications, improving efficiency and real-time control over building operating costs Beside that it makes financial sense for businesses to monitor, respond, and lead the trend toward greater building energy efficiency. For building developers, smart design techniques and highefficiency building components are the key to maximizing energy efficiency. The starting point for operators and occupants is to make energy management a business priority. More generally, looking at total costs over the life-cycle of a structure should underpin decision-making for everyone involved in a building. Industry associations, to date, have not played a significant role in this change, leaving initiatives largely to government. This trend differs from the U.S. and Europe where industry initiatives are one of
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the driving forces behind a market-led transformation toward greater efficiency and sustainability in the built environment. As the global movement towards more sustainable growth gains momentum that would have surprised many people even five years ago, business and governments will have to re-think their assumptions and chart new ground. References [1]
Barcelona Climate Change Talks 2009 - IPCC Side Event "Scientific knowledge to meet the challenge of climate change: the most policy-relevant scientific findings to be highlighted by leading IPCC experts" - Barcelona, Spain, 3 November 2009 http://www.ipcc.ch/presentations_and_speeches/presentations_and_speeches_presentations.ht m#2
[2]
Sustainable Urban Infrastructure London http://www.mckinsey.com/mgi/publications/
[3]
World Business Council on Sustainable Development (WBCSD) Energy Efficiency in Buildings Business realities and opportunities www.wbcsd.org
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The Impact of Stakeholder Decision Criteria on Global Carbon Abatement in the Building Sector Kevin Otto1, Christian Kornevall2, William Sisson3 2 Robust Systems and Strategy LLC, The World Business Council for Sustainable Development, 3 United Technologies Corporation
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Abstract Looking to 2050, the IEA has projected scenarios with various carbon reduction levels, where the “Blue Map” scenario achieves carbon stabilization levels. The carbon abatement cost curve depicts costs versus carbon abated for a rank ordered set of abatement strategies. A carbon cost of $300/ton for all aggregated sectors will bring about the Blue Map result. However, these scenario analyses estimate the total cost to society, total investments less costs and savings. The estimates do not consider who pays these costs and who receives the benefits. The analysis implicitly suggests that the lowest negative cost options will happen and can thereby pay for more costly abatement measures. For example, improved insulation levels result in a net negative carbon abatement cost, which could pay for the implementation of more costly renewable energy supply. A common misunderstanding of the carbon abatement curve interprets it as defining the carbon price needed to bring about the stated efficiency levels. Rather, we find substantial price insensitivity to carbon and correspondingly much higher carbon prices are needed to influence building sector decision making for energy efficiency measures. To determine this, the WBCSD Energy Efficiency in Buildings project (EEB project) created a model of building stock turnover to compute energy efficient technology adoption levels based on micro-economic investor stakeholder decisions. Rather than an unacceptably high market carbon price to foster change, we found that only a set of aggressive policy measures implemented together to influence decision making would bring about building sector transformation to the levels needed.
Background A key issue in carbon emission projections into the future is the spectrum of capital investment choices that will be made by investors or owners, and the impact on energy consumption of these choices. These decisions are micro-economic, considering available capital, changes in operating expenses, payback, and changes in non-economic criteria such as image and altruistic motives. Very different future outcomes can occur depending on how such choices are made (WBCSD 2007). Unfortunately, most scenario projections ignore the micro-economic decision made by stakeholders on energy efficiency improvements. Rather, marginal carbon abatement “cost to society” is the macroeconomics considered to compare effectiveness of various measures. While appropriate for macro-economic cost assessments, this approach will substantially mask the real costs experienced by various capitalexpenditure decision-makers and what incentives are necessary to entice or push them into more energy efficient actions. A key sector is buildings, representing 40% of energy consumption globally. In this paper, we present a system of models the EEB project constructed to show how the building stock in a submarket will change over time based on different technologies. The newly adopted technologies are microeconomically preferred for the stock under construction or renovation in any given year, due to different prices and efficiencies (WBCSD 2009). The results are used to consider the carbon costs necessary to motivate the buildings industry stakeholders. In the next section we discuss related work and scenario projections. We then present the EEB project’s building stock decision making model. We end by presenting projection results for different submarkets under different scenarios, and we can conclude what incentives and programs are effective at motivating radical transformation of the building stock. Scenarios and Global Carbon Reductions Global carbon emission future scenarios have been created through extensive data collection and model based projection analysis by various well established entities including the International Energy Agency (IEA). There are various notable projections (IEA 2008), including the Baseline, or Business 138
As Usual (BAU) projection, which takes current energy consumption trends and projects them to 2050, resulting in an unsustainable 62 Gt of CO2 emissions and 550 ppm carbon concentration. Another scenario is the Accelerated Technology (ACT) projection, which includes sufficient capital investments in energy efficiency and renewable to achieve carbon stabilization by 2050 at 28 Gt of CO2 emissions and 485 ppm carbon concentration. Lastly, the Blue Map (BLUE) projection, which includes sufficient capital investments in energy efficiency and renewable to achieve carbon reductions by 2050 at 14 Gt of Cow emissions and a 445 ppm carbon concentration, the level stated by IPCC as necessary to stabilize projected global warming (IPCC 2007). These different scenarios and all between require an increasing set of measures to achieve the increasing levels of carbon reductions. As others before, the IEA has estimated overall cost to society of these measures, and depicted the maps on an carbon abatement marginal cost curve chart, shown in Figure 1. This curve, complete with an uncertainty range on costs, depicts the overall marginal carbon abatement cost to society when implementing an increasing number of measures, rank ordered from left to right on cost. Moving to the right as more CO2 emissions are curbed through an increasing set of measures, the cost to society increases. Figure 1: IEA Carbon Abatement Cost (IEA 2010).
This assessment by IEA makes clear the marginal cost of carbon to society as a whole. To achieve global temperature stabilization as the BLUE Map scenario, the cost is between $200 and $500 per tonne of CO2. The marginal cost of carbon is correct to consider for entire societal cost. It is misleading, however, to use this as a figure of what carbon price is needed to motivate the various measures shown. For example, the first 15 Gt CO2 have a net negative marginal cost. This is entirely correct, the cost savings over the life of energy efficient equipment often more than pays for the increased cost. But for equipment with a 20 year life, this implies purchases with a 20 year payback. This is not how micro-economic decisions are made, and the actual carbon price needed to motivate the measures can be substantially higher. In this paper, we explore this carbon price and other measures that can motivate the building sector to adopt these end-use efficiency measures. Related Work The IEA has completed several series of well researched reports on sector carbon emissions, trends, technology opportunities, and projections. The World Energy Outlook (IEA 2009) presents current demand trends. The Energy Technology Perspectives report (IEA 2008) resents global energy and carbon projections. These works provide the foundation for our EEB project work on refined costs for sector stakeholders. Underlying the IEA projections is the MARKAL modeling framework (IEA 2010), used internationally by many groups. The United States uses a different but similar modeling framework to project energy demands (EIA 2009). All represent the generation, transmission, conversion and end use of energy.
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Each of these functions has alternative technologies for which the MARKAL model makes economically optimal choices, given macro-economic scenarios such as carbon pricing, etc. All these works represent building efficiency choices as simple savings versus first cost decisions, considering each efficiency improvement as additive. This is sufficient for energy analysis of many sectors, but insufficient for energy analysis within the building sector as it ignores the interactions that exist between choices. We incorporate synergies between efficiency improvement interactions as well as their impact on economic decision making, and further explore interactions of incentives, prices, and building codes. Other related works include studies of technology adoption rates in the building sector. Zhao et al (2009) define adoption rates for various residential and commercial building technologies in the Chinese market. The IEA has published cost improvement experience curves for various technologies (2000). The American Council for an Energy Efficient Economy (ACEEE) has published capabilities for different building technologies (2004). These and other technology capability and cost projections were used in our work.
WBCSD Modelling of Stakeholders’ Decisions on the Building Stock Model Structure As part of the EEB project, the WBCSD undertook a modelling effort to project what it will take to bring about radical transformation of the building stock, in terms of building sector actor and other stakeholder actions. Key questions included what are required of the building sector industry, construction, financing, trade organizations and governments. To quantify these considerations, a model of how the building stock changes due to micro-economic decisions of building owners and stakeholders was necessary. This is different from a traditional MARKAL model in two respects – we were concerned only with the building sector end use, and the capital investment decisions needed to be modeled at higher fidelity than simply assuming complete adoption of the technology alternative with higher payback than others. The model developed is a conglomeration of separate submodels, as shown in Figure 2. The analysis operates on a submarket basis, such as residential single family homes in the Southeast United States, or mid-rise office buildings in the Kanto Region of Japan. A homogenous set of buildings is needed for the analysis, in terms of provided service levels. The model represents a building as 23 energy related subsystems and materials, including wall insulation, roof insulation, fenestration selections, lighting systems, daylighting levels, primary heating equipment, primary cooling equipment, thermal distribution systems, ventilation systems, passive thermal measures, renewable generation systems, etc. For each such subsystem, various technology options are defined with energy efficiency and first cost parameters. A building alternative is a selection of one technology option for each of the 23 energy related subsystems, defining a very large space of available building configurations. The year 2005 was chosen as the baseline reference year, and a representative set of buildings was defined in terms of energy related subsystem selections. In the model, each building alternative has a (possibly zero) level of building stock.
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Figure 2: WBCSD Building Stock Decision Selection and Emssion Projection Model. Construction Option Packages Outcome Building Energy Metrics Data Updated Building Simulation Stock Levels Operational Behaviors Initialize with
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Further, each energy-related subsystem has an age, from new to end of useful life. For example, most HVAC equipment has a useful life of 20 years. With this representation, every year a percentage of the building stock in the model is refurbished and decisions over new subsystems selections made. Further, a fraction of the building stock is destroyed and removed from the stock model, and a fraction of new construction also occurs adding again new subsystems and building alternatives into the stock. These three modes of building stock change are used in the model, essentially defining a year-overyear differential equation of the building stock. The new and refurbished building stock is determined through a rank ordering of alternatives according to the micro-economic decisions of a modeled set of stakeholders. That is, each building alternative is simulated using a whole building energy simulation such as DOE2 or EnergyPlus (DOE 2010). These results provide the synergistic energy savings of different subsystem technology combinations for a building. The energy savings then provide a payback against the incremental first cost, where we also have a first cost model of materials and installation for each technology alternative. Using these figures, a rank ordering can be defined. This can substantially vary according to macro-economic conditions such as the price of energy, price of carbon, technology learning curves, and also due to government policy incentives or taxes. We further model the impact of building codes by eliminating from consideration alternatives that do not meet different building energy codes at different levels of code. The micro-economic decision submodel represents several stakeholders who have impact on the capital equipment selection, depending on the decision dynamics of the submarket. We do this through allowing different economic criteria to be the objective function and other decision criteria to be filtering constraints on the selection decision. For example, owner-occupiers might make decisions based on simple economic payback. Owner-tenant buildings, however, do not, since the owner likely pays the first cost whereas the tenant might receive the benefit of lower monthly energy costs. In such arrangements, the linkage between an owner’s decision over first costs and perceived benefits are tenuous. In our model, we represent these situations with a multi-stakeholder decision filtering method. That is, we assign one of the stakeholders as the decision maker, such as the owner. They likely have an objective of minimizing first costs. On the other hand, the tenants may prevent this unilateral choice because they will not accept systems with annual costs higher than a certain level. This would define one possible owner-tenant decision model. In our research with stakeholders, we found the typical situation is one where the owner will accept a first cost increment upper bound over the lowest cost alternative, while minimizing the annual operating costs for the tenants. However, this varied by submarket. We also built the model to explore non-monetary micro-economic decision factors. We built the model to explore conditions were a decision maker does not use first costs or annual operating cost criteria,
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but instead makes decisions either wholly or in part by criteria such as impact on indoor environmental quality, operational uptime, or green criteria. One could argue that such criteria can be quantified as an economic value increase, but such value is very difficult to quantify. Therefore, we built the microeconomic rank ordering algorithm to accept any generic utility function, whether economic or noneconomic. What is needed is a rating of each alternative on the criteria, and a utility function to combine these ratings into an overall score for each alternative. Generally, we found data on noneconomic criteria very difficult to determine for a comprehensive assessment across all energy related subsystems. Nonetheless, we did explore runs where we defined and considered such decisions. The outcome we arrived at, however, was that whatever the decision making criteria, one could always establish an equivalent extended payback period. That is, one could generally describe noneconomic decision criteria in an economic fashion through larger payback and first cost limit criteria. Green decision makers look like economic decision makers with extended payback on energy costs. Whatever the specific microeconomic objective criteria and filtering constraints, the year after year result is a sorted list of the preferred alternative building configurations, independently for new construction and retrofits. Our approach is to then convert this rank ordering into a distribution of building stock alternative increments for that year. If an alternative has high rank ordering, it is assigned a higher percentage of building stock increment that year. Thereby, the building stock alters year after year according to the micro-economic decisions being made. These incremental calculations on the building stock are iteratively made from 2005 to 2050. With the building stock level projections calculated to 2050, the associated energy consumption and carbon emission projections are also aggregated. This is done for any macro-economic scenario defined, in terms of energy prices, carbon prices, technology learning curves, and government policies such as incentive programs, tax programs, and building energy efficiency codes. Representative Submarkets Modelled The modelling requirements are very data intensive. Cost and efficiency curves are need for each technology alternative on all 23 energy related subsystems. Submarket statistics are needed on stock levels of types and age of insulation, fenestration, heating and cooling equipment, lighting, etc. Building energy consumption levels and construction cost expenditure statistics are also needed. Also, stakeholder decision making criteria must also be determined, either by first hand research, statistical inference, or both for data verification. This information can be very hard to attain, particularly at a submarket level, and one never acquires all possible data. On a submarket case by case basis, we did acquire sufficient data to be reasonably confident of the model calibration and projections. Given this difficulty, we did not model every submarket. Rather, a sample of submarkets was analyzed across six global regions, as shown in Table 1. From these representative detailed results, estimates were also projected for global figures. This sample was deemed representative of different market geographies, economies, and segments, and sufficient calibration data was deemed attainable. Table 1: Submarkets Analyzed with the WBCSD Model. Submarket United States Southeast Single Family Homes Japan Kanto Region Mid Size Offices France Single Family Homes US Northeast Large Offices China Northern Large Apartment Buildings Brazil Shopping Malls
Carbon Pricing Impact on Stakeholder Decisions and the Building Stock Across all industries the IEA BAU and BLUE scenarios project 2050 global emission levels of 62 and 14 Gt CO2 respectively. Therefore the BLUE scenario depicts a 48 Gt CO2 reduction from BAU. Of the 62 Gt CO2 BAU projection by IEA, 20.1 Gt CO2 are due to the building sector. Of the 48 Gt CO2
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reduction in the BLUE map projection, we compute that 15.5 Gt CO2 reduction is coming from buildings, including both buildings and the percent of emission reductions from renewable power generation within buildings. Therefore the question becomes what is needed in macro-economic conditions to drive building stakeholders to reduce building carbon emissions by 15.5 Gt CO2 by 2050, including both efficiency measures and onsite renewable generation. Impact of Typical Policy Incentives Considered Today Current macro-economic policy schemes deemed aggressive include efficiency incentives on building materials and equipment of 30%. Further, incentive programs on renewables such as photovoltaics or solar thermal hot water systems of 65% and a 5X feed-in tariff are aggressive measures. These policies were used to compare their impact against having no policies at all, and the results are shown for the French Single Family Residential submarket and the Japan Office submarket in Figure 3. Figure 3: Impact of Current Typical Building Efficiency Policies s n io lli B
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While there are substantial differences between the two submarkets (the Japan office building market is shrinking whereas French single family homes are growing in number), the result between the business as usual (BAU) and typical policies is very minimal. There is no discernable carbon emission difference between the blue curve of the BAU projection and the red curve projecting the impact of typical building efficiency incentive programs. That is, to first order, the policies are having no impact on the decisions being made. The mildly more energy-efficient equipment being selected under these incentive programs would have been selected anyway by the stakeholders. Impact of $300/ton Carbon Price The next question is what the impact would be of carbon pricing, either through a carbon tax or a carbon cap and trade system. The impact of either approach is a price on the cost of carbon. The BLUE map scenario of Figure 1 suggests a marginal cost to society of $300 per tonne of CO2 is needed. Imposing an additional operating cost of $300 per tonne of CO2 resulted in reduced carbon emissions as shown in Figure 4, again for the French single family homes and Japanese office buildings. As can be seen, paying this extra carbon price again has negligible impact on capital investment decisions of the building stakeholders. In their micro-economic decisions, they would rather simply pay the extra operating expense. This should not be surprising, since building energy costs are a relatively minor
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expense to building stakeholders. The mortgage cost or rent is a much higher cost than energy, and $300 per tonne of CO2 only has a slight increase to the total price of energy. Figure 4: Impact of $300 per tonne CO2 Carbon Price s n o li il
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Impact of 5X Energy Price (or equivalently, $700/tonne CO2 in the US) Given that $300/ton CO2 has little effect, what level of carbon pricing will move the market? A perhaps better question is what operating cost multiplier will drive the market to adopt higher-cost higherefficiency capital, and then allow the carbon tax to be determined according to the local market’s electrical grid carbon intensity. For example, a 2.8X energy cost increase would occur in the United States through a $300/ton CO2 carbon price. Figure 5: Impact of 5X Operating Cost s n io lli B
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Imposing an energy cost multiplier of 5X results in reduced carbon emissions as shown in Figure 5, again for the French single family homes and Japanese office buildings. As can be seen, when using operating economics alone, little impact occurs. This result is due to the first cost limits expressed in the micro-economic model; decision makers are often unwilling to spend more than an upper bound, no matter how large a payback. Such limits are generally at most a 25% first cost premium (compared to the lowest first cost alternative), for solutions that payback within a short timeframe. Removing these first cost upper limits (and allowing the decision to be based on total cost) would show more impact, but this is not how stakeholders make investment decisions. On the other hand, at more extreme operating costs of 5X or more, such first cost upper bounds are likely violated. In the United States, we calculate that a 5X energy price increase would consume a substantial portion of the average disposable income. In this scenario, we find stakeholders are faced with conditions beyond the data available on how decisions are made. The first costs of low energy equipment are too high and the operating costs of standard equipment are too high. Unfortunately, there is no known data of how building stakeholders will respond to capital investment decisions when placed under such extreme operating expenses of 5X or higher. Therefore, it is not possible to state definitively what carbon price is needed to drive building stakeholders to adopt low energy solutions based on higher operating costs alone; all we do know is that the costs are high. Short of that, we ran additional model experiments. Removing the first cost limits and simulating the situation where decision makers made investment decisions based on total cost did improve the carbon emission results, but not to the extent expected by us or others. There is a problem in having many alternatives for stakeholders to choose, from alternatives with no improvements to alternatives with only partial improvements to complete zero energy buildings. With so many alternatives, then more-often-than-not decision makers chose more familiar partial solutions rather than transformative very-low-energy alternatives, even when the alternatives had equivalent cost. Figure 6: Impact of 5X Operating Cost and Alternatives Restricted to Limit Cases s n o li il
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This lead us to ask what operating cost multiplier was required to drive adoption of zero energy buildings, when all partial improvement solutions were not allowed. A decision maker could select the business-as-usual standard alternative or the very low energy building alternative, but no other. With this (artificial) micro-economic alternative set, we found a 5X operating cost increase was needed to initiate building stock transformation in most markets, as show in Figure 6. In terms of carbon pricing (depending on the local carbon intensity of the grid) this equates to $700 per tonne of CO2 in the US. Such as carbon price is not likely realistic. Further, this carbon price only makes very low energy buildings economically equivalent to the standard alternative and as shown in Figure 5, total cost equivalency alone does not make decision makers want to adopt them.
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Impact of Incentives on Whole Building Measures From these results, it is clear that neither individual incentive programs nor realistic carbon pricing alone will impact the building sector. Our modeling suggests that the problem is both that energy price is comparatively not significant to the building sector, but also that the industry is risk averse and so doing a few measures is deemed sufficient (WBCSD 2007). The result is no radical transformation needed. Given this, different macro-economic schemes were considered beyond carbon pricing. The most promising involves incentives and whole-building measures. That is, rather than offering incentives on added insulation or higher efficiency boilers, a different approach is needed to incentives. Incentives should only be awarded to buildings which meet aggressive energy intensity levels. For example, the insulation and boiler rebates will be given only to buildings which have an energy intensity of 50 kWhr/m2/yr or less. We modeled this approach, and the results are shown in Figure 7. Figure 7: Impact of Incentives provided only the low energy intensity buildings s n io lli B
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The results are strikingly improved. This suggests the needed policy framework and approach for the building sector. A building energy rating certification system is needed to prove a building meets an energy intensity level. Based on improvements to that intensity rating, increased incentives should be made available. On the other hand, based on poor energy intensity ratings, construction permitting bans should be imposed. The other important message derived from this result is that the building sector only responds to first cost incentives and construction codes, and that increased operating expenses have little impact on capital expenditure decisions. Impact of Transformational Policies: $30/ton Carbon Price and Incentives on Whole Building Measures Given these results on incentives and whole building energy efficiency measures, providing the macroeconomic conditions to foster transformation of the building stock is feasible. However, this places a burden on governments to pay for the cost of transformation. This scenario can be augmented with a mild carbon price for a government to offset these incentive programs. We show in Figure 8 the impact of whole building energy intensity incentives, whole building energy intensity building codes, and a $30 per tonne of CO2 carbon price. This combination of policies provides the macro-economic conditions to foster transformation of the building stock.
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Figure 8: Impact of whole building Incentives and Codes, and a $30 per tonne CO2 price s n io lli B
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Summary The objective of our study was to understand the level of carbon costs or other measures necessary to motivate the buildings industry stakeholders to transform the building energy stock to low energy performance. Generally, the package of policies that define macro-economic conditions that foster the building sector transformation were not obvious and took some time to generate. To see these results on a marginal carbon abatement curve, we analyzed the subsystems adopted, their costs and their energy savings for any of these policies. The results can be compiled into a carbon abatement curve using the real costs expended and operating costs saved over the life of the equipment. This carbon abatement curve is shown in Figure 9 for the transformational set of policies whose impact are depicted in Figure 8. As can be seen it is generally possible with these policy measures to achieve the levels of the 15.5 Gt CO2 reduction required by the building sector to meet its contribution of the 48 Gt CO2 reduction called for by the IEA BLUE Map scenario. Figure 9: Projected Global Carbon Abatement Cost Curve Under Transformational Policies 1000
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On the other hand, it is also clear that neither subsystem incentives nor carbon price alone will impact the building sector, due to low energy costs of a building compared to other costs such as rent or mortgage. As a single measure, carbon prices alone would have to be much higher than $300/ton discussed to begin to sway building sector decision makers based on operating costs. Generally, we find carbon prices are needed that would increase energy cost by about 5 times current energy costs. This requires carbon prices orders of magnitude higher than currently being discussed, whether through cap and trade carbon pricing or carbon taxes. Such pricing is likely not feasible. Instead we find incentives, codes and mild carbon pricing, properly structured, will have a bigger impact.
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IEECB'10 - HVAC
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New Liquid Desiccant Cooling Systems for Buildings: Performance and Applications Joan Carles Bruno, Joan Carles Esteban, Núria Quince, Alberto Coronas Universitat Rovira i Virgili, Mechanical Engineering Dept., CREVER – Research Group on Applied Thermal Engineering
Abstract The aim of this paper is to briefly present the fundamentals of the liquid desiccant cooling technology for building applications including a description of the basic parameters commonly used to characterise its performance. A simple model for liquid desiccant cooling systems using an appropriate model to calculate the required thermodynamic properties is used to show its main operational parameters air flow and solution flow rates, air inlet properties, etc. In the second part of the paper are presented several existing system configurations implemented commercially or under development in some demonstration projects. Also it is presented an implementation of a liquid desiccant unit with a nominal air treatment capacity of 6000 m3/h installed in the Primary health care centre “Roger de Flor” in Barcelona (Spain). This building has a potential energy saving of 29% with respect to a conventional building and was awarded as member of the European GreenBuilding Programme. Introduction and objectives The electricity consumption in the tertiary and residential sectors represents the 57% of the total for the EU-27 [1]. This electricity consumption has grown by 15.6% and 14% in the period 1999-2004 for both building sectors, respectively [2]. One of the main applications of electricity is space heating and cooling. The consumption of electricity for these applications is about one-third of the total electricity consumed in buildings [2]. Thus it is not surprising the high interest on the development of air conditioning technologies driven by low-temperature heat sources, such as solar, waste and similar sources of low-grade heat. Absorption cooling is the most developed thermal cooling technology. However, the use of desiccant cooling systems also known as open sorption cooling systems opens new possibilities in airconditioning technology. Desiccant systems are used to produce conditioned fresh air directly without any intermediate cold liquid medium such as chilled water in absorption chillers, can be driven at much lower temperatures than those for absorption chillers and are easy to integrate with conventional vapour compression heat pumps. Desiccant cooling machines are designed to dehumidify and cool the ventilation air to meet the required supply air conditions for buildings. Desiccants can use solid or liquid sorption materials. Liquid desiccants are potentially more efficient [3] and compact than solid desiccant systems, can eliminate pollutants and bacteria from ventilation air and are generally regenerated at relatively lower temperature. Nowadays a few manufacturers are offering this kind of technology for building applications combined with different heat sources, mainly waste heat from cogeneration or solar thermal energy. The aim of this paper is to briefly present the fundamentals of the liquid desiccant cooling technology for building applications including a description of the basic parameters commonly used to characterise its performance. A simple model [4] for liquid desiccant cooling systems using an appropriate model to calculate the required thermodynamic properties [5] is used to show the main operational parameters such as air flow and solution flow rates, air inlet and outlet properties, etc. In the second part of the paper are presented several existing system configurations and technology solutions implemented commercially in some demonstration projects or under development. Also it is presented in detail an application case of a liquid desiccant unit in an energy efficient building with a nominal air treatment capacity of 6000 m3/h installed in the Primary health care centre “Roger de Flor” in Barcelona (Spain). This building has a potential energy saving of 29% with respect to a conventional building and was awarded as member of the European GreenBuilding Programme.
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Fundamentals of Liquid Desiccant Cooling Systems (LDCS) Dehumidification is the process of removal of water vapour from moist air. It can be usually achieved by cooling or by absorption/adsorption of moisture by a solid or liquid material (called a desiccant). Desiccants are materials that have a high affinity for water vapour. Both solid and liquid desiccant systems can be used for dehumidification and cooling. The main advantages of liquid systems include improved indoor air quality (acting as disinfectants), simultaneous cooling during dehumidification, possibility to use a single regenerator for multiple conditioners and storage capability of the desiccant solution. And the potential drawbacks are corrosion (except for glycols), carryover of solution into the air stream and crystallisation of salt. Almost all metal alloys are corroded by the most effective liquid desiccants particularly in the presence of oxygen. The higher the concentration and lower the temperature, the higher the moisture absorbed and the lower the humidity. But at high concentrations and low temperatures, there is a possibility of crystallisation of the desiccant due to solubility. The concentration level depends on the type of desiccant, for example for LiCl it is 30 – 45%, 35 – 45% for CaCl2 and 90 – 98% for triethylene glycol (TEG) as mass fraction. The most commonly used absorbents are aqueous solutions of lithium chloride, calcium chloride and TEG although other desiccants and mixtures can be used. The absorber and regenerator are generally linked through a liquid-to-liquid heat exchanger to reduce the regenerator residual heat (Fig. 1). It precools the warm concentrated solution transferred to the absorber using the cool dilute desiccant from the outlet of the absorber. The sensible heat load may be effectively removed with evaporative cooling if the supply air is first dehumidified to the right point.
Figure 1. Schematic diagram of a typical Liquid Desiccant Cooling system (LDCS). Basic performance parameters The performance of LDCS can be defined in terms of some non-dimensional efficiency parameters related with humidity and enthalpy differences [6]: humidity and enthalpy effectiveness. Humidity effectiveness εy is defined as the ratio of actual change in humidity ratio of the air across the LDCS to the maximum possible change in humidity ratio of air (g water/kg dry air). The maximum possible difference in humidity ratio of air is obtained when the outlet air is in equilibrium with the inlet
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desiccant solution, that is, when the partial pressure of water in the air is equal to the vapour pressure of water in the inlet desiccant solution and the driving force for mass transfer is zero (Pa,out = Ps,in)
εy = where
ω a,in − ω a ,out ω a ,in − ω e
ω a,in and ω a,out are the humidity ratios of the air at the inlet and outlet dehumidifier streams,
respectively. These variables can be calculated using the measurements of temperature, relative humidity and pressure in the corresponding streams assuming a mixture of dry air and vapour:
ω = 0.622 ⋅
Pv Patm − Pv
This parameter can also be defined in terms of the partial pressure of air instead of its humidity ratio:
εp =
Pa,in − Pa ,out Pa,in − Pe
Another parameter for the efficiency measurement the enthalpy effectiveness can be defined as the ratio of actual change in enthalpy of the air across the system to the maximum possible change in enthalpy of air. Similar to humidity effectiveness, the maximum possible difference corresponds to equilibrium with the inlet desiccant solution.
εh =
ha ,in − ha ,out ha ,in − he
Other parameters that can be of interest to measure are the actual reduction in the humidity ratio of air, the change in temperature of air, the lowest possible humidity level achievable and also the ratio of liquid to gas flow rates for its impact on parasitic power consumption and carryover/drift [6]. Of course, to these parameters we have to add the COP of the overall air conditioning system of high interest for HVAC engineers. Modelling and technical performance For the study of LDCS systems numerous researchers have used complex finite difference models. The numerical models require empirical correlations for the mass transfer coefficients. Other studies are based on the development of empirical correlations for dehumidification effectiveness [6]. In this section a simplified method proposed by Gandhidasan [4] is presented just to illustrate the basics of liquid desiccant systems using a preliminary approach. A more detailed model description can be found in reference [4]. The overall energy balance for the dehumidifier (fig. 2) can be written as:
Ga ⋅ ha ,i + Gs ⋅ hs ,i = Ga ⋅ ha,o + G s ⋅ hs ,o The notation used in this equation corresponds to that given in fig. 2. This energy balance can be simplified using the following assumptions: − −
The specific heat of the fluids and latent heat of condensation is constant with respect to the temperature. The vapour pressures are very small in comparison with the atmospheric pressure.
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Figure 2. Schematic and used nomenclature for the absorber model. Thus the energy balance can be written in a simple form as:
Cp a ⋅ (Ta ,i − Ta,o ) + 0.622 ⋅
G λ ⋅ ( pa ,i − pa ,o ) = s ⋅ Cp s ⋅ (Ts ,o − Ts ,i ) Pa Ga
The specific heat capacity for the solution streams can be obtained from some available correlations for LiCl [7] as a function of the temperature and solution concentration. The solution concentrations at the inlet and outlet of the absorber can be introduced in the model using the relation proposed by Kim et al (1997) [8] as it was suggested in the liquid desiccant model of Gandhidasan [4]:
1 1 m = ⋅ 1 + xo xi Gs
And the mass flow rate of water condensed from the humid air and absorbed by the strong desiccant solution can be calculated by:
m = Ga ⋅
0.622 ⋅ ( pa ,i − p a ,o ) Pa
This model can be easily applied with the introduction of data from variables that can be quite easily measured from a liquid desiccant system. The results in Table 1 are an example of application to show how with this simple model it could be possible to obtain preliminary results for some important system variables such as the temperature and concentration for the desiccant solution at the absorber outlet and the amount of condensed water. Table 1. Example of results using the model proposed by Gandhidasan [4]. Ga (kg/m2s)
1.176
Gs (kg/m2s)
6.309
Ta,i (ºC)
29.9
ωi (g water / kg air)
0.0178
Ts,i (ºC)
35,2
xi (%)
34.9
2430
Ts,o (ºC)
35,4
xo (%)
34.87
λ (kJ/kg)
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m (g/s)
0,2234
εp
0,72
ωo (g water / kg air)
0,0136
This model has been implemented in the Engineering Equation Solver using experimental data from Fumo and Goswami (2002) [9] as it was made by Gandhidasan [4] and the thermodynamic properties for LiCl from [7]. It was concluded that the maximum difference between the measured and calculated mass flow of condensed water was 10% [10]. Also the same model was applied for the regenerator unit of the desiccant system. In this case the maximum differences were even smaller (around 5%) in spite of the simplicity of this model [10]. Present Liquid Desiccant cooling technology and market Solid and liquid desiccant cooling systems can be incorporated into commercial air-conditioning (HVAC) systems. They are being used either as stand alone units integrated with evaporative cooling systems or hybrid units in conjunction with vapour compression or absorption chillers. In a hybrid system the chilled water is passed through the absorber to simultaneously cool and dehumidify the air. In contrast, in a hybrid solid desiccant system the air has to be first dehumidified in a desiccant wheel and later cooled in a cooling coil. In this case no further moisture needs to be added in a evaporative cooler to achieve cooling and the required dehumidification in the LDCS can be lower.
Figure 3. Schematic of liquid desiccant aided vapour compression air conditioning [11]. Figure 3 shows a possible configuration for the integration of LDCS into conventional vapour compression systems to reduce its size and enhance its coefficient of performance. Because the latent load is handled independently by the desiccant dehumidifier, the need of cooling the ventilation air below its dew point is obviated. The temperature of evaporation can thus be lifted up to 15 ºC from its generally practiced level of 5ºC for the traditional vapour compression system. The increase in evaporation temperature will entail the increase of the system’s coefficient of performance (COP). This assemblage can be useful in humid climates where the wet bulb temperature is fairly high. In such climates, a significantly downsized vapour compression air conditioner can be supplemented with a desiccant assisted evaporative cooler in order to reach the desired indoor temperature, thus enabling costs and energy savings and improving the indoor air quality. Desiccants use components similar to those in chemical industries for liquid-gas sorption processes. But for LDCS these should be designed to handle large process air and low desiccant flow rates. The air pressure drop through the absorber should be as small as possible, while providing large surface
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areas per unit volume for contact between air and the desiccant. The carryover of desiccant with the air stream is a problem in liquid systems, partly due to drift and to vaporisation of some solutions at high temperatures. Several technical solutions are used to put air and desiccant solution into close contact: spray tower, packed bed tower and wetted wall or falling film columns. In a spray tower arrangement large surface area for heat and mass transfer is obtained by breaking the liquid into small droplets with the help of nozzles in a spray chamber. Although spray towers are well known for their simplicity, low pressure drop on airside, low cost and compact size, but their effectiveness in absorption is not high [6] and also liquid carryover can be a significant problem. Sprayed coils, cross flow plate heat exchangers and heat pipes are the designs used in spray towers that can provide simultaneous cooling. Packed bed towers are well known for their compactness, high efficiency, large contact area and large contact time. Two types of packing are generally used, random and structured packings. Random packings provide good contact between air and the desiccant but the required desiccant flow rates for good wetting and the air pressure drops are generally high. Structured packings are usually more effective but these designs do not allow internal cooling. Wetted wall column is a vertical tube or plate over which the desiccant solution flows by gravity. The air comes into contact with the surface of the flowing liquid film. These columns have low pressure drop and initial cost. The difficulty arises in achieving a thin film over the complete cross section of large towers. There are a few commercial LDCS manufactures in the world. Some deliver whole air conditioning system solutions, while others have a more limited scope, such as handling the latent load only. Some of the most active and recently incorporated into the market of LDCS for building or small-scale applications are: Ducool, Menerga and AIL Research along with some traditional manufacturers such as Kathabar that is from January 2008 a subsidiary of Niagara Blower that provides also its own dehumidification units. Kathabar systems can be considered as typical LDCS found mostly in industrial applications and using a proprietary salt mixture in aqueous solution [12]. DuCool [13] commercialises a series of LiCl LDCS that can be provided with external heating and cooling for regeneration and dehumidification and also integrated with a heat transfer system to produce heating optionally (fig. 4). Another important feature of this system is that when the level of the diluted solution in the absorber increases as it absorbs more moisture from the treated air, it passes to the regenerator thanks to the communicating vessels effect through a membrane only permeable to water. One of the Ducool units is under testing at the Politecnico of Turin (Italy) with the collaboration of the Universitat Rovira I Virgili (Spain) [14]. Another unit using a membrane for the exchange of water between the two solutions was commercialised by Drykor but including also a heat pump. In this unit the concentrated desiccant was cooled before entering the absorber by the evaporator of the heat pump and the condenser provided the energy necessary to regenerate the diluted solution. In this configuration the heat pump can be operated at a high COP but unfortunately the units have mostly had a short life due to corrosion problems at the condenser and evaporator. These units ceased to be manufactured in 2006 [12]. AIL Research [15] produces a LDCS based on the used of plastic plate heat exchangers to avoid the problem of solution carryover and the corresponding corrosion in other downstream HVAC components. The conditioner is a parallel-plate heat exchanger in which the plates are water-cooled. Films of desiccant flow in thin wicks on the outer surfaces of the plates. The process air flows through the gaps between the plates and comes in contact with the desiccant. The desiccant absorbs water vapour from the air, and the heat that is released is transferred to the cooling water. The flow rates of liquid desiccant in both the conditioner and the regenerator are very low, typically a factor of 10 to 20 lower than in conventional packed-bed liquid-desiccant equipment. This system is intended to handle latent load only. A beta prototype operated 250 h during summer 2008 in the United States without any degradation of the performance [16]. The German manufacturer Menerga commercialises air handling units combining air dehumidification with indirect evaporative cooling. Some other manufacturers are L-DCS, Ficom, Jilier and Genius [6].
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Figure 4. Ducool liquid dessicant system including an integrated heat pump and auxiliary heating and cooling (Ducool [9]). Demonstration plant at the Primary Health Centre “Roger de Flor” In this section it is presented an implementation of a liquid desiccant unit with a nominal air treatment capacity of 6000 m3/h installed in the Primary health care centre “Roger de Flor” in Barcelona (Spain). 2 This building is a seven floor building with a useful area of 3000 m including office-type rooms and public areas (fig 5).
Fig. 5. Building model and picture of the Primary health centre “Roger de Flor” in Barcelona. The main energy savings measures are listed bellow: − − −
Passive elements, will regulate the relationship between natural daylighting and solar protection. Natural ventilation promoted by the open ground floor and the central glazed court. The heat and cold distribution using low temperature radiant ceilings permits to reach high coefficients of performance of the compression chiller and the condensing gas boiler.
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− − − −
An innovative energy efficient liquid desiccant dehumidifier with lithium chloride solution is integrated in the ventilation system. Photovoltaic solar panels for electricity production and Solar Thermal panels for heating and domestic hot water. The whole building is equipped with fluorescent lamps and high frequency electronic ballasts. A Building Management System will also contribute to reduce the energy demand of the building controlling the air conditioning and the lighting system.
The heat and cold distribution system using ceiling panels allows low working temperatures of 40 °C for heating and relatively high working temperatures for cooling (15 -17 °C). The heat is produced to approx. 20 % by a high efficiency gas condensing boiler (151 kW) and to approx. 80 % by an electrical heat pump used for heating as well as cooling purposes (240 kW for cooling and 245 kW for heating). A small contribution to the heat demand by the solar thermal panels is also expected. This plant consist of 23 m2 of flat plate collectors on the building roof. The photovoltaic consists of two plants of poly-crystalline cells: a 5.4 kWp of semitransparent modules integrated on the south-west façade of the building and a 4,5 kWp plant of opaque modules integrated on the roof of the building facing south-west. The heat and cold distribution by radiant panels integrated in the suspended ceilings make necessary an independent air treatment in order to adjust the humidity to comfort levels and to prevent condensation on the cooled ceilings. For dehumidification an innovative energy efficient liquid desiccant dehumidifier with lithium chloride solution will be integrated in the ventilation system. Initially a mixture of LiCl+CaCl2 was used but it will be replaced by lithium chloride. The AHU integrated with the LDCS produces heating and cooling in two modes: summer and winter. In summer (fig. 6) the outside air is filtered, precooled and later it goes through the evaporator tube bundle of a three-stage compression heat pump using R-407C. Next it is dehumidified with the absorber of the LDCS. Part of the cooling capacity of the evaporator is used to cool the absorber and increase the dehumidification capacity. The extracted air from the building is first preheated in the condenser tube bundle of the heat pump and used to regenerate the diluted solution of the LDCS. In winter mode the dehumidification system is not used and the ventilation system handles only the sensible load.
Figure 6. Schematic of the ventilation system operating in summer mode. The mechanical ventilation system also integrates an enthalpy plate exchanger to recover the heat of the extracted air and pre-heat the outside air before it is introduced in the building, thus contributing to significant energy savings during the winter operation mode. The system consist of a battery of vertical 157
heat-pipes with a refrigerant fluid in vapour-liquid equilibrium in such a way that the warm extracted air evaporates the liquid refrigerant and later condense it by heating the outside air. The ventilation and the air treatment systems will also be able to function as free-cooling during intermediate seasons (spring and autumn). This building has a potential energy saving of 29% with respect to a conventional building (Table 2) and was awarded as member of the European GreenBuilding Programme. The cooling energy demand was calculated by dynamic building simulations with TRNSYSlite and the heating energy demand was calculated according to the calculation method of DIN EN 832 using the German program Thermplan. The energy demand values of the reference standard building have been obtained using typical energy consumption data of office buildings provided by ICAEN (Catalan Institute of Energy) which were adjusted according to available data from existing primary health care centres in Catalonia.
Table 2. Expected primary energy demand savings Standard Building
Primary Health Care centre
Primary energy demand [kWh/m²a]
Primary energy demand [kWh/m²a]
Primary energy savings [%]
Heating
83.1
47
43.4 %
Cooling
85.2
61.9
27.3 %
Lighting
174
131.7
24.3 %
DHW
27.2
13.5
50.4 %
Others
24
24
0
TOTAL
393.5
278.1
29.3 %
The work to monitor this LDCS in order to calculate and optimise its performance has been started (Esteban, 2009) and will continue when the system will run again with the new LiCl solution and after the determination of the necessary new instrumentation and their economic cost because usually the information available in demonstration plants is considerably limited in comparison with experimental plants and some parameters for example, solution concentration are not measured because although there are important to model the system this parameter is not important for the system control and is not directly measured. Additionally it could be interesting to have some measurement redundancy in certain key components such as the absorber in order to apply some kind of data reconciliation methods to improve measurement accuracy, detect systematic errors in the measurements due to measuring devices that for any reason fail (calibration, location, ...) and estimate non-measured variables.
Conclusions The liquid desiccants are attractive because of their operational flexibility and their capability of absorbing pollutants and bacteria. Compared to the solid desiccants, they are generally regenerated at relatively lower temperature and, equally cause lower airside pressure drops. Their disadvantage is their carryover in the process air stream during the dehumidification operation.
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Current manufacturers offer liquid desiccant units that address some of the main characteristic limitations of liquid desiccants for air conditioning and using for solution regeneration low grade thermal energy such as solar thermal energy or waste heat from conventional heat pump or cogeneration systems. Although it could not be considered a fully commercialised technology several demonstration sites using LDCS in energy efficient supply systems are offering interesting results. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16]
Eurostat statistical books. Energy yearly statistics 2007, 2009 Edition. http://epp.eurostat.ec.europa.eu Atanasiu, B., Bertoldi, P., Electricity consumption and efficiency trends in the enlarged European Union – JRC Status report 2006. JRC Workshop on Effective policies for improving energy efficiency in buildings. Krakow (Poland), 2007. Öberg, V., Goswami, D.Y., Performance Simulation of Solar Hybrid Liquid Desiccant Cooling for Ventilation Air Preconditioning. ASME Solar Engineering, 176-192, 1998. Gandhidasan, P., A simplified model for air dehumidification with liquid desiccant. Solar Energy 76, 409-416, 2004. Conde, M., Aqueous solutions of lithium and calcium chlorides: property formulations for use in air conditioning equipment design. M. Conde Engineering, 2009. Jain, S., Bansal, P.K., Performance analysis of liquid desiccant dehumidification systems, International Journal of Refrigeration, 30, 861-872, 2007. Conde, M., Aqueous solutions of lithium and calcium chlorides: property formulations for use in air conditioning equipment design. M. Conde Engineering, 2009. Kim, K.J., Ameel, T.A., Wood, B.D., Performance evaluation of LiCl and LiBr for absorber design applications in the open-cycle absorption refrigeration system. Transactions of the ASME Journal of Solar Energy Engineering 119, 165–173, 1997. Fumo, N., Goswami, D.Y., Study of an aqueous lithium chloride desiccant system: air dehumidification and desiccant regeneration. Solar Energy 72, 351–361, 2002. Esteban, J.C., Master Thesis, Universitat Rovira i Virgili, Tarragona, 2009. Daou, K., Wang, R.Z., Xia, Z.Z., Desiccant cooling air conditioning: a review. Renewable and sustainable energy reviews 10, 55-77, 2006. st Conde, M., Liquid desiccant-based air-conditioning systems – LDACS, 1 European Conference on Polygeneration, Tarragona, Spain, 2007. Ducool, www.ducool.com Badami, M., Bruno, J.C., Coronas, A., Ortiga, J., Portoraro, A., Preliminary experimental results of a liquid desiccant cooling system and comparison with empirical correlations, 9th IIR Gustav Lorentzen Conference on Natural Working Fluids, Sydney, Australia, 2010. AIL Research, Inc., www.ailr.com Lowenstein, A., The application of Liquid-desiccant air conditioner to solar cooling, 3rd int. Conference Solar Conditioning, Palermo, Italy, 2009.
Acknowledgement The authors would like to acknowledge the partial funding of this work by the GreenBuilding Plus project, Intelligent Energy - Europe Programme, EIE-07-109.
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Morphological implications buildings architecture.
of
passive
techniques
in
office
Luca Finocchiaro1, Tore Wigenstad2, Anne Grete Hestnes1 Department of Architectural Design, History and Technology, NTNU 2 Sintef Building and Infrastructure, Trondheim 1
Abstract The study hereby presented aims to analyse the relationship between the shape of the building and its energy consumption in cold climates. Thirteen virtual buildings were obtained by aggregating a basic office unit in different ways and then simulated. Monitored data, collected from eleven Norwegian office buildings, have also been reported inside the same diagrams to verify the accuracy of the study conducted. The analysis showed that the respect of exigent low energy standards permits a significant reduction of the heating consumption but that the increased need for cooling partially compensates this benefit; this is questioning the total convenience of using compact shapes and super-airtight envelopes in cold climates if not combined with a proper strategy for natural ventilation, passive cooling or solar control. Introduction Although the relationship between the morphological characteristics of a building and its energy consumption has already been deeply investigated in the last decades, continuous development in technologies, together with a grade of uncertainty arisen from unpredictability of climate change, opened once again the problem of the most appropriate shape for a specific climatic context. Super insulating and airtight envelopes, developed to protect the interior space from extreme cold climates, are overturning upside down the problem; the elevated internal thermal gains due to occupancy and equipment today became the main determinant of shape and strategy in office building design. The following study aims firstly to establish a relation between the shape of a building and its energy consumption in cold climates and secondly to comprehend how the current tendency to use airtight envelopes is affecting the traditional presumption of total convenience of compact shapes in cold climates. Definition of the shape coefficients Thirteen different shapes have been obtained aggregating the same basic office unit in different ways and then tested through ECOTECT, a simulation tool commonly used to give a first estimation of the energy consumption of a building already during the design process. Differences among the various shapes have been registered through 4 shape coefficients that measure and compare the general characteristics of the theoretical models. The first two parameters used, (1) and (2), measure the compactness of the building, defined as the ratio between the total surface Sg enveloping the building ground floor included - and its total volume Vt (1). The formula (2) compares the total surface Sg to the surface Seq of an equivalent sphere of the same volume of the building2, assumed as the reference for maximum compactness (C=1).
Sg Vt
(m −1 )
(1),
C=
S eq Sg
2
= 4 ,836
Vt 3 ≤1 Sg
(2)
In the calculation of the global surface the following have been excluded: - Patios, if the exposed surface amounts to more than a 1/6 of the total surface - Irregularities of the facades, if contained within 1 meter from the average surface. The third parameter (3) is the slenderness and it is calculated as the ratio:
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e=
(
h h = d S0 + h2 π
(3)
)
where d is the diagonal d = h + r , h the height of the building and r the radius of the equivalent circle of area S0 (average surface of the different floors, usually coinciding with the footprint of the building). The Wall/Volume ratio (4) represents the last parameter used and has been introduced during the development of the study; it relates the vertical facades area to the total volume of the building: 2
2
Sw
Vt
(m −1 )
(4)
No parameter has been considered to measure the porosity of the theoretical models (zero for hypothesis).
Material and methods In order to be easily aggregatable, the basic unit has been structured on a squared plan of M=5 meters of side. The percentage of glass in vertical facades has been fixed to the 40%.
Figure 1. The basic unit used to shape the theoretical models.
The basic unit can assume 27 different thermal exchanges configurations depending on its position inside the building. Specific characteristics of the theoretical models, reported on the left side, have been fixed in accordance to the Norwegian regulation in force TEK07. Depending upon its orientation - N, S, E, W, NE, NW, SE, SW, Central - and location inside the building - top, any intermediate or ground floor - the basic unit can assume 27 different configurations of possible thermal exchanges (Figure 1). Consequently the heating and cooling demands of the basic unit have been calculated 27 times before proceeding to the aggregation into the theoretical models. Specific and technical characteristics of architectural components have been fixed in accordance to the Norwegian regulations in force TEK07 and a number of 180 units have been arbitrary chosen in order to obtain a heated surface of 4500 square meters, comparable to a standard office building.
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In order to test the reliability of the methodology developed, a monitored case study has also been simulated in ECOTECT. Although the building was mostly characterized by landscape plans, it has been necessary to divide each floor in different thermal zones in relation to orientations. The thermal demand calculated has then been compared with another simulation conducted on the same building in SIMIEN6; both the softwares resulted in a good approximation to monitored data (Figure 2).
Figure 2. Bravida office building – simulations.
Simulations conducted in SIMIEN and ECOTECT showed an appreciable proximity to the monitored data. It has also been necessary to prove the equivalence between the thermal zones simulated as a whole and the same ones performed as sum of units. For the central zones it resulted immediately equivalent working in any of the two methods, while for the peripheral ones a significant difference could be appreciated (figure 3): a) dividing the corner units in two triangular thermal zones b) calculating the thermal demand of the entire squared corner units and then dividing it in two
Figure 3. Definition of the simulation methodology.
The simulation performed dividing the corner units in two different triangular thermal zones (a) resulted being more proximal to the thermal zone performed as a whole assumed as reference R. The first methodology (a) resulted in a closer approximation to the reference thermal zone calculated as a whole. Theoretical models have been adjusted consequently dividing the corner units into two triangular thermal zones. Partial results showed that (Figure 4): - corner zones present a higher demand for heating due to the larger thermal losses happening through a more extended glass façade - in central zones the need for cooling represents almost 50% of the total thermal demand. - No big differences could be appreciated in relation to orientation and vertical position of the units.
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Figure 4. Thermal demand of the 27 units internal to the 3M*3M*3h cube simulated. 70,00
70,00
70,00
60,00
60,00
60,00
50,00
50,00
50,00
40,00
40,00
40,00
30,00
30,00
30,00
20,00
20,00
20,00
10,00
10,00
10,00
0,00
0,00 N
S
E
W
NE
NW
SE
SW
C
0,00 N
S
E
W
NE
NW
SE
SW
C
N
S
E
W
NE
NW
SE
SW
C
a) floor b) intermediate c) roof The need for heating in corner units results significantly higher because of the larger dispersions happening through the more extended glass surface. The need for cooling represents almost the 50% of the total demand in central units.
Results Once that the thermal demand of the 27 basic units has been calculated, the energy consumption of any theoretical model could have been obtained as a sum of them; results would have been influenced by the prevalence of central units - typical of deep plans typologies - or corner units – typical of high-rise or articulated buildings (Table 1). The thermal demand of the theoretical models has then been related to the shape parameters, in order to individuate the most influential ones (Figure 5). The heating demand resulted directly proportional to the Wall/Volume ratio; this was clearly due to the glass surface determining the thermal losses and the consequent need for heating (since volume is constant among the different theoretical models). No one of the compactness parameters, counting also the roof surface, in fact, defined such a clear proportionality as the Wall/Volume ratio (TEK07 reduced significantly thermal losses through roofs). A sequence 1-3-4-4-1 characterized the heating demand in relation to the slenderness; responsible of this scattering is the height h of the building as pointed out in the figure 5 (the three numbers reported on the right side of each point represent the number of units used to define the different shapes – side, side, floors – giving all 180 office units – see also Table 1).
Figure 5. Thermal demand of the theoretical models related to the four shape coefficients. Wall/Volume Slenderness Compactness A/V
2
Cooling demand (Kwh/m y) 20,00
19,00
18,00
17,00
16,00
15,00 0,00
0,20
0,40
0,60
0,80
1,00
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Table 1. Theoretical models - Morphological analysis and thermal load.
The same sequence - 2 floors, 3 floors, 5 floors, 10-12 floors, 45 floors buildings - going from horizontal slabs to vertical towers, can be easily recognized inside the cooling demand diagram where the Wall/Volume ratio and the slenderness seem to be the most influential shape coefficients. When related to the slenderness, the cooling demands of buildings of the same tallness appear concentrated on the same vertical line, independently from any other characteristics. This happens because the
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slenderness parameter doesn’t take in account the articulation of the plan (assigning to articulated and compact plans the same value). Both heating and cooling demands resulted related to the wall/volume ratio but, while the need for heating depended more upon the glass area and the consequent thermal losses, the cooling demand was more related to the possibility of ventilating and the air-tightness of the envelope. This presumption is confirmed by the following charts that present a further analysis underlining the completely different behaviour between heating and cooling demand in case of different air-tightness values of the external skin (figure 6). The first row of charts is referred to the heating demand and shows how the direct proportionality to the Wall/Volume is maintained independently by the airtightness value (the gradient of the relation diminishes in case of increased air-tightness). On the other hand, going from 2,5 to 0,6 ach, the cooling demand looses the dependency on the Wall/Volume ratio and starts being more and more related to the compactness of the plan with a significantly high gradient. This happens because, in case of airtight envelopes, the need for cooling is more related to the compactness of the plan and the possibility of ventilating; on the other hand in case of no air-tight traditional envelopes (2,5 ach) the cooling demand is still affected by the thermal losses happening through the glass area, that cope with the elevated internal gains.
Figure 6. Thermal demand and air tightness. 90,00
Wall/Volume
Compactness
45,00
Wall/Volume
20,00
Compactness
88,00
43,00
18,00
86,00
41,00
16,00
84,00
39,00
14,00
82,00
37,00
12,00
80,00
35,00
10,00
78,00
33,00
8,00
76,00
31,00
6,00
74,00
29,00
4,00
72,00
27,00
2,00
70,00 0,00
25,00 0,00
0,20
0,40
0,60
0,80
1,00
a) heating demand - 2,5 ach 16,00
Wall/volume
0,20
0,40
0,60
0,80
1,00
b) heating demand - 1,5 ach
Compactness
20,00
Wall/Volume
0,00 0,00
Compactness
30,00
19,50
29,50
15,00
19,00
29,00
14,50
18,50
28,50
14,00
18,00
28,00
13,50
17,50
27,50
13,00
17,00
27,00
12,50
16,50
11,00 0,00
0,20
0,40
0,60
0,80
1,00
0,60
0,80
1,00
Wall/Volume
Compactness
26,00
15,50 15,00 0,00
0,40
26,50
16,00
11,50
0,20
Compactness
c) deating demand - 0,6 ach
15,50
12,00
Wall/Volume
25,50 0,20
0,40
0,60
0,80
1,00
25,00 0,00
0,20
0,40
0,60
0,80
1,00
a) cooling demand - 2,5 ach b) cooling demand - 1,5 ach c) cooling demand - 0,6 ach Heating and cooling demand shows completely different behaviours in relation to air tightness; the heating demand maintains its direct proportionality with the Wall/Volume ratio, independently by the number of air changes per hour; the cooling demand, in case of super tight envelopes, results being directly proportional to the compactness. Ten Norwegian case studies have been finally reported inside the precedent diagrams to prove their liability and accuracy; the projects have been chosen for variety of shape and strategies used and consequently present markedly different thermal behaviours3 (LECO project - low energy office buildings). The thermal demand of the theoretical models has been calculated using three groups of parameters (Tr.Syst. – traditional construction, TEK07 and LE low energy standards – Table2) and using different low energy strategies - super windows, mixed ventilation - in different moments. Each simulation resulted in a different translation of the thermal demand/shape line, which anyway continued keeping a pretty low gradient. Each case study resulted relatively close to the proportional line effectively corresponding to the strategy used, confirming a certain accuracy of the study conducted (Figure 7).
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Figure 7. Thermal demand of the theoretical models and comparison with the monitored case studies.
Monitored data from eleven different case studies have been reported on the diagrams drawn on the theoretical models simulation results. Each case study resulted being proximal to the proportional line corresponding to the low energy strategy effectively used.
Conclusions The study conducted individuated the Wall/Volume as the most significative shape parameter. It’s also been proved that while the need for heating is related to the thermal losses happening through the glass area, on the other hand the need for cooling is related to the compactness of the plan and the consequent possibility of ventilating and coping with the high thermal loads typical of office buildings. Compared to the translation that can be obtained through the use of a proper strategy, the contribution of any shape variation seems to be negligible; on the other hand the shape can play a significant role
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in enhancing the potentialities of the low energy strategy used. Further research on the morphological coefficients should focus more on this aspect.
Table 2. Parameters used for the simulations. Unit W/m2/K U-value external wall W/m2/K U-value roof W/m2/K U-value floor on ground U-value windows, glazed walls and W/m2/K roofs ach Air-tightness Heat recovery system efficiency persons/m2 Occupancy °C Cooling set point temperature °C Heating set back temperature W/m2 Lighting load W/m2 Equipment load
Trad.syst. 1.2 0.60 0.50 2.4
TEK07 0.15 0.13 0.18 1.2
LE 0.15 0.13 0.18 1.2
3.0 0.7 0.1 26 18 8 11
1.5 0.7 0.1 26 18 8 11
0.6 0.85 0.1 26 18 8 11
If the respect of even more exigent Low energy standards – LE – permits a further reduction of the heating consumption, on the other hand the increased need for cooling partially compensate this benefit, questioning the convenience of using compact shapes and super-tight envelopes if not combined with a proper strategy for ventilation, passive cooling or solar control (figure 8).
Figure 8. Thermal demand of the 9 office units in case of different air-tightness. 120,00 100,00 80,00 60,00 40,00 20,00 0,00 N
S
E
W NE NW SE SW C
a) 2,5 ach – traditional systems
70,00 60,00 50,00 40,00 30,00 20,00 10,00 0,00
40,00 30,00 20,00 10,00 0,00
N
S
E
W
NE NW SE SW
b) 1,5 ach – TEK07
C
N
S
E
W NE NW SE SW C
c) 0,6 ach – LE standard
Acknowledgement This paper has been written within the ongoing SINTEF project ‘‘LECO” on low energy commercial buildings. The authors gratefully acknowledge the Research Council of Norway.
References [1]
Haase, M. and Andresen, I. 2008. Key issues in energy-efficient building envelopes of Norwegian office buildings, XXX
[2]
Rafael Serra Florensa. 2005. Arquitectura y energia natural, alfaomega grupo editor
[3]
Haase, M., Andresen I., Berit Time and Anne Grete Hestnes. 200X. Design and future of energy-efficient office buildings in Norway, XXX
[4]
A.E.Kohn & P. Katz, Building type basics for office buildings, John Wiley and sons Inc., New York, 2002
[5]
P. Depecker, C. Menezo, J. Virgone and S. Lepers, 2001, Design of buildings shape and energy consumption
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[6]
Catherine Grini et al., LECO-energibruk i fem knotorbygg i Norge, Sintef Byggforsk Prosjectrapport 48, Oslo 2009
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Assessing the energy performance of HVAC systems in the tertiary building sector by on-site monitoring Marco Masoero, Chiara Silvi, Jacopo Toniolo Dipartimento di Energetica - Politecnico di Torino
Abstract The paper discusses the collection and processing of energy performance data as part of the inspection of HVAC systems, aimed at identifying technically feasible and cost-effective Energy Conservation Opportunities (ECOs), as required by the European Directive on Energy Performance of Buildings (EPBD). Case studies developed by the IEE-funded HARMONAC project have shown that low-cost or no-cost ECOs - mostly related to system operation and management (O&M) - can be identified with an effective system monitoring. Building Management Systems (BMS) may be a powerful tool for this task, provided their HW and SW architecture is designed with adequate attention to energy monitoring. Dedicated instrumentation – such as temperature loggers and electricity meters – may also be employed as an alternative / integration to BMS monitoring. The paper also discusses the application of data analysis tools – such as “carpet plots” and “energy signatures” – to the identification of component malfunctioning, control problems, inadequate maintenance, or system schedule optimization, and to the evaluation of achieved energy savings. The final section of the paper is dedicated to the detailed in situ analysis of refrigeration equipment performance. List of abbreviations AHU: BMS: COP: DHW: ECO: EPBD: HVAC: HP: IEE: O&M: RH: TXV: VRF:
Air Handling Unit Building Management System Coefficient of Performance Domestic Hot Water Energy Conservation Opportunities Energy Performance of Buildings Directive Heating, Ventilating and Air Conditioning Heat Pump Intelligent Energy Europe Operation and Management Relative Humidity Thermostatic Expansion Valve Variable Refrigerant Flow (heat pump)
Introduction The Intelligent Energy Europe (IEE) funded HARMONAC project [1], due to completion in August 2010, is developing a set of inspection and energy audit procedures suitable for fulfilling the requirements of article 9 of EPBD [2], which establishes the mandatory inspection of HVAC systems of rated output above 12 kW. The procedures proposed by HARMONAC are now being tested by the project partners over a wide range of field trials and case studies throughout Europe. One of the key points of the inspection procedure is the availability of reliable energy performance data of the main components of the HVAC system. This task is usually easy for heating only systems, such as gas boilers coupled to hydronic heating plants, but much more complex for systems delivering both heating and cooling. In the latter case, in fact, most system equipment (e.g., water chillers, cooling towers, air handling unit (AHU) fans, chilled / hot water pumps, fan coils, etc.) are electricallydriven, but the electricity consumption is seldom measured in a disaggregated way. Normally, the only available electrical consumption data are those measured at the main incomer; therefore, such data also include the contribution of lighting and appliances. One of the main problems that have been addressed by the HARMONAC team has therefore been the definition of energy data collection protocols, suitable for an effective inspection and energy auditing process of existing HVAC systems.
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This paper presents the main findings obtained by the authors through the energy and performance monitoring of a set of tertiary buildings in Northern Italy, including laboratories, hospitals, and offices of different ages. HVAC systems that have been investigated include air, water, and air-water units (with fan coils or chilled beams), air cooled chillers, reversible heat pump (HP) systems of various characteristics: variable refrigeration flow (VRF) air-to-air HP, closed-loop ground source HP, open loop water to water HP. A sample of case studies from the HARMONAC project are presented in this paper, as summarized in Table 1. Specifically, the following issues are discussed: • How to obtain reliable and sufficiently disaggregated energy consumption data using the existing BMS, and which SW and HW features are required for this purpose. • Data collection with low-cost dedicated instrumentation (electric meters, temperature and RH loggers, etc.) as an alternative or integration to BMS monitoring. • Approaches to energy data processing - e.g. correlation of primary energy consumption with climatic conditions and occupancy characteristics - and determination of suitable energy performance indexes. • Identification and assessment of cost-effective Energy Conservation Opportunities (ECOs) [3], which have been implemented in practice and checked in actual case studies: examples include modified operation schedules, improved control strategies, maintenance or improvement actions on specific HVAC components. Table 1. Case studies: building and HVAC system characteristics Type / location 1.
Operating NW Italy
Area (m2)
Main HVAC system characteristics 3
rooms
15500 m /h outdoor air (15 ach) AHU 300 2 air-cooled chillers, 394 kW total output
2.
Office building NW Italy (Aosta)
Air-and-water HVAC (four-pipe active chilled beams) 3500 2 chillers + evaporative tower, 650 kW total output
3.
Office building NW Italy (Torino)
4.
Public building
9400
Air-to-air reversible VRF heat pump, 600 kW heating, 550 kW cooling output. 5 primary air AHUs Two-pipe fan coil system, no mechanical ventilation
4000 NE Italy 5.
6.
open-loop groundwater-cooled chiller, 330 kW output
Retirement home
30000 heated
NE Italy (Trieste)
8000 cooled
Office building NW Italy (Genova)
Four gas/oil boilers, 6823 kW output 3 chillers + evaporative towers 1468 kW total output Air-and-water HVAC (two-pipe active chilled beams)
8600 2 chillers + evaporative tower, 1868 kW total output
Results indicate that primary energy savings typically in the 5%-25% range, and up to 60% in peculiar circumstances, may be reached by applying low-cost (or no-cost) measures identified by analysing data that are acquired with dedicated instrumentation, or are provided by a BMS that has been properly designed, installed and commissioned for energy monitoring. The final section of the paper discusses the experimental method that may be applied for a detailed in situ analysis of the energy performance of chillers and heat pumps. This approach - which requires the installation of a portable dedicated instrument, and skilled personnel for interpretation of results - may
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be a very powerful diagnostic tool for identifying equipment defects such as low refrigerant charge, fouled evaporator / condenser, poor compressor efficiency, etc.
Data collection and processing Hardware and software requirements of BMS Most tertiary buildings of new construction, or undergoing radical refurbishing, are now being equipped with sophisticated and powerful computer-based Building Management Systems (BMS), which monitor and control mechanical and electrical equipment such as lighting, power supply, fire prevention, security, and HVAC [4]. BMS can effectively perform energy metering (fuel consumption, electrical energy input to specific components, delivered energy to fluid networks), provided the energy metering functions are clearly indicated among the design specifications of the BMS in terms of installed instrumentation (electricity meters, temperature sensors, fluid flow meters, etc.), and SW characteristics. Our experience indicates, however, that adding such capability to an existing BMS implies very high costs and technical problems that are sometimes impossible to overcome. The experience gained in using existing BMS for HVAC energy monitoring has yielded several hints which may eventually lead to a complete specification. The following is a non-exhaustive list of recommendations to the designers and installers: • Electric meter characteristics (type of data collected, accuracy, data storage) and number (e.g. separate chillers + cooling tower, pumps, AHU). • Thermal energy meters: specifications for hot water and chilled water flow rate and temperature measurements. • Environmental data measurements: indoor and outdoor air temperature and RH. • Time coding: the data acquisition time interval should be specified by the user, typically in the range from 15 minutes up to 1 hr, depending on the type of data; the time sequence of collected data should never be interrupted, which means that, if for any reason the data are not collected at a given time, a conventional figure should be recorded. Daylight saving time should be managed in a non-ambiguous manner. • Data format: the correspondence between data and physical quantities should be clearly specified with alphanumeric codes that make the identification easy to the inspector. Data collection with dedicated instrumentation As an alternative or integration to BMS monitoring, specific data may be collected with dedicated instrumentation. Ambient temperature and relative humidity (RH) data are easily obtained with standalone, battery powered loggers. Status loggers should be used to monitor, at relatively low cost, the operation schedule of small fixed power appliances, such as constant speed electric motors of HVAC equipment (typically, constant flow fans and water pumps, fan coils, etc.). The logger simply logs the on/off status of the component by a magnetic field sensor or a single current transformer clamp. More relevant electrical users should be monitored with energy meters that may be installed on the electric board. In recent plants, the electric meter may be already present, in which case it may be sufficient to connect the meter to a suitable data logger. The most sophisticated measurement units are the so-called “power / energy analyzers”, which can provide a complete set of data including active and reactive power, power factor, and the corresponding energy values over a specified integration interval. Power quality analyzers may also provide information on the waveform (e.g. the total harmonic distortion). A summary of the instrumentation characteristics is given in Table 2. Table 2. Metering instruments utilized Instrument Typical values Acquisition time logged Electrical power meter kW, kWh, VAh, PF 15 minute T/RH logger (stand-alone) °C, RH (%) 1 hour Status logger (ON/OFF) On/Off status 1 second (*) COV = Change of value
Memory
Cost (€)
1 year 300-1000 6 months 120-250 8000 COV(*) 100
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Analysis of energy monitoring data As discussed above, the monitoring process should typically yield the disaggregated values of primary (electric) energy consumption of the main system components. These values are supplemented with a suitable set of environmental and occupancy data, recorded over the same time scale, that are likely to influence the system energy demand. The level of disaggregation of the acquired data varies significantly from case to case: in some buildings, the total electrical consumption was only available (i.e. the typical “billing data” provided by the electric utilities), while in other cases the BMS allowed the separate measurement of the energy input to the main HVAC sub-systems (e.g., dedicated meters for: chillers and cooling towers; water circulation pumps; and Air Handling Units). For some HVAC systems, dedicated equipment was installed for a detailed analysis of “critical” components, such as the AHU of the operating block of a hospital. The availability of such data sets makes it possible to perform an energy analysis, based on the socalled “data-driven” modeling approach. According to ASHRAE [5], data-driven methods for building / HVAC energy analysis may be classified into three broad categories (Black-Box, Calibrated Simulation, or Gray Box), depending on the type of available data and goals of the analysis. Furthermore, the mathematical approach may vary depending on the basic assumptions, such as steady-state vs. dynamic modeling, or single-variate vs. multivariate regression, etc. In this research, a steady-state, single-variate approach has been applied, considering the daily (or weekly) mean outdoor temperature as the independent variable, and the corresponding daily (or weekly) primary energy consumption of the specific equipment (or system) under investigation. The reason for this choice is that outdoor temperature is the most readily available climatic variable for the inspector, and is also likely to have the main influence on HVAC primary energy consumption. This is a crucial aspect of the inspection process: to be able to get the maximum information from readily available data that may be useful for ECO identification and assessment. Another useful tool for energy data analysis is the so-called “carpet plot”, which provides a visually grasping representation of temperature or energy consumption trends over long time periods: time of day is indicated on the y-axis, while the day is represented on the x-axis; the value of the variable under observation is encoded, at any time and date, as a colour or shade of gray according to a specified scale [6]. Even if the information provided by the carpet plot is rather qualitative, it allows a meaningful and quick interpretation of the overall system performance in time. This may be particularly useful for identifying anomalous situations, such as excessive energy consumption in non-occupancy periods which may be caused by unwanted equipment operation, or unsatisfactory temperature values due to poor control. An example of best practice in building and HVAC system data monitoring Case study n. 6 is an insightful example of best practice in building and HVAC system monitoring. The 16 floor office/laboratories tower, built in 2003, hosts the headquarters of a company that designs and produces communication systems. The building is equipped with an air-water, two-pipe active chilled beams HVAC system; mechanical ventilation is provided by three AHUs. The building is connected to a district heating network. The cold generators are two water chillers (with screw compressors and evaporative towers) rated at 934 kW cooling capacity each, with a maximum electrical input of 207 kW. The building is equipped with an electrical consumption metering system, connected in parallel to the BMS (but functionally independent), which logs the following data at a 15 minutes sampling rate: • Global electrical income • AHU electrical consumption • Chilled water pumps electrical consumption • Chillers electrical consumption • Total thermal energy to the building (from the district heating) • Thermal consumption for space heating • Thermal consumption for DHW • Total water consumption • Evaporative towers water consumption
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The logged data were helpful to analyze in detail the HVAC sub-systems consumption and schedule. A sample of results is presented in the following graphs. Figure 1 represents the breakdown, over one year of operation, of electrical consumption into three terms: i) chillers; ii) water pumps; iii) AHUs and small VRF units; iv) non-HVAC uses. As expected, the chiller consumption exhibits a marked variation from month to month (with a maximum in July), while the consumption associated to other equipments are virtually constant over the year. The temperature-dependence of chiller consumption is clearly visible in the regression analysis of Figure 2, while for the AHU the consumption is virtually temperature-independent (the slight positive slope of the regression line is likely to depend on the small VRF systems that are measured with the AHU fans). Figure 1. Electrical uses breakdown based on annual monitoring Genova office Summer MWh Genova office electricity consumption
Ahu+small VRV+pump s+ev.towers consumption Chillers
6%
600.0
non HVAC
11%
non HVAC Chillers Ahu,small VRV pumps
500.0 400.0
9%
300.0 200.0 100.0
74%
0.0 gen
feb
mar
apr
mag
giu
lug
ago
set
ot t
nov
dic
Figure 2. Electric consumption vs daily mean external temperature for different users Chillers VS Ext Temp
AHU + small VRV VS Ext Temp
y = 185.95x - 2141.5 2 R = 0.7695
3500.0
3000.0
3000.0
2500.0 2000.0
2000.0
kWh
kWh
2500.0
1500.0
500.0
500.0 0.0 17.0
19.0
21.0
23.0
25.0
27.0
29.0
°C
0.0 15.0
17.0
19.0
21.0
23.0
25.0
27.0
29.0
°C
Total HVAC VS Ext Temp
y = 270.78x - 748.72 2 R = 0.7181
8000.0 7000.0 6000.0
• Top left: Electric input to chiller compressors, evaporative tower pumps, chilled water pumps • Top right: Electric input to AHU fans and small direct expansion VRF units
5000.0 kWh
1500.0 1000.0
1000.0
15.0
y = 30.087x + 1401.6 2 R = 0.3215
4000.0 3000.0
• Bottom left: Electrical consumption to all HVAC components
2000.0 1000.0 0.0 15.0
17.0
19.0
21.0
23.0
25.0
27.0
29.0
°C
Carpet plots are also used to represent in a single graph the data collected over one year at a sampling rate of one hour; the colour scale refers to hourly energy consumption in kWh. The two plots of Figure 3 allow a quick appreciation of the control strategy applied to the two chillers. Figure 3. Carpet plots of chiller electric consumption (unit A, left; unit B, right)
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The plots of fig. 3 reveal that, in the periods of maximum cooling load, unit A operates at maximum power, while unit B operates at partial load; however, when the demand is lower, both units work at partial power. This type of information is extremely useful in evaluating the efficacy of the control strategy being applied, both in terms of energy efficiency and system maintenance procedure. The carpet plots of figure 4 refer to pumps (chilled water and cooling tower water) and to AHU fans and secondary circuits pumps consumption. The first plot permits to clearly identify the period of pump operation, while the electric consumption is virtually constant when the pumps are on. The AHU electric consumption, however, basically depends on the ventilation needs, which are linked to the occupancy period of the building. Figure 4. Carpet plots of electric consumption of pumps (left) and AHUs (right)
One last example of carpet plot is shown in figure 5, which refers to the thermal energy measured at the secondary side of the heat exchangers interfacing the building’s hot water circuits to the district heating network. Here the plots provide a clear picture of the thermal load over the entire heating st st season (October 1 to March 31 ). Figure 5. Carpet plots of thermal energy at secondary side of district heating heat exchangers
Evaluation of Energy Conservation Opportunities Table 3 summarizes the ECOs that have been identified and evaluated as part of some of tje case studies of Table 1, with an assessment of expected energy savings. All ECOs belong to the O&M (Operation & Maintenance) category and may therefore be implemented at virtually no-cost. Table 3. Examples of ECOs assessed on measured data ECO description
Potential savings
1.
Avoid simultaneous heating and cooling
61.5% on winter chiller consumption
2.
Improvement of chiller control
8-15% on annual chiller consumption
3.
Shut off chiller when not required
30% on annual chiller consumption
4.
Shut off VRF system when not required
26.7% on weekly winter VRF consumption
5.
Reducing operation time of chiller
6.2% per hour of daily operation reduction
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Case Study 1: Inspection and monitoring of the operating rooms of a general hospital The experimental setup for the monitoring of the three operating rooms is shown in Figure 6. The graphs in Figure 7, representing the indoor and outdoor temperature values measured over a five week period in November – December, indicate that the HVAC system does not always allow a satisfactory temperature control during surgical activities (i.e. T > 22°C), even with low outdoor temperatures and with the chiller continuously operating at about 25% load. This circumstance can be better appreciated in the carpet plot on the right part of the figure. Figure 6. Operating room HVAC monitoring experimental setup
EC1:
electric chiller no. 1
EC2:
electric chiller no. 2
Pc1:
active power of EC1
Pc2:
active power of EC2
TcIN:
cold water supply temperature
TcOUT: cold water return temperature PUTA:
AHU fan active power
T1-T3: temperature and RH of surgery rooms 1-3 Text:
outdoor temperature
Figure 7. Outdoor and operating room temperatures and carpet plot of room temperature. 30 25
°C
20
T ext ROOM 1 ROOM 2 ROOM 3
15 10 5
11 Dec
09 Dec
07 Dec
05 Dec
03 Dec
01 Dec
29 Nov
27 Nov
25 Nov
23 Nov
21 Nov
19 Nov
17 Nov
15 Nov
13 Nov
11 Nov
0
Potential energy savings with improved chiller control is assessed with medium term measurements, carried out from December to February. This ECO consists of avoiding simultaneous heating and cooling and shutting off the chiller when outdoor temperature falls below a set level, which, for typical cooling load values, was assumed 14°C. Over the investigated four-week period (Fig. 8), the chiller electric consumption occurring when the external conditions satisfy the requirement for free cooling is 4879 kWh, i.e. the 61.5% of total chiller consumption (7979 kWh). Extrapolating these figures to the entire year, and taking into account the results of a similar analysis performed in case study n. 2, savings of 8-15% in annual chiller consumption may be expected in comparable climatic conditions.
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Figure 8. Outdoor / indoor temperature - chiller electric consumption (December – January) POLITO FT-SRI Chiller hourly consumption VS Temperature (22 Dec 2008-18 Jan 2009) Chiller consumption
Ext. Temp
Surgery room Temp
16
24 22
14
20 18
12
16
14°C
14
10
12
8
°C
kWh
10 8
6 6
4 2
4
0 -2 -4
2
-6 11:00
17:00
23:00
05:00
11:00
17:00
23:00
05:00
11:00
17:00
23:00
05:00
11:00
17:00
23:00
05:00
11:00
17:00
23:00
05:00
11:00
17:00
23:00
05:00
11:00
17:00
23:00
05:00
11:00
17:00
23:00
05:00
11:00
17:00
23:00
05:00
-8 11:00
0
Case study 2: Inspection and monitoring of an office building of recent construction The inspection of a new office building in NW Italy indicates a relatively high HVAC electric consumption, in spite of state-of-the art system components and building envelope, particularly in relation to the climatic conditions of the site. In fact, BMS monitoring data show that about 39% of the total summer electric consumption (51 kWh/m2) may be attributed to the central cooling plant (20 kWh/m2), 96% of which due to chillers and cooling tower and 4% to water circulation pumps. These results suggest that significant savings may be achieved by improved chiller control and scheduling. More detailed analyses performed in the winter season reveal, for example, that simultaneous heating and cooling take place in the AHU under specific circumstances. A detailed monitoring over the January – May period indicates that an improved control strategy, capable of switching off the chiller and exploiting direct free cooling with outdoor air when the outdoor temperature permits, may lead to a 35% reduction in central cooling plant consumption over the investigated five months period. Another identified ECO is the possibility of turning the cooling plant off at night and during weekends: the BMS data in fact reveal no significant differences in chiller energy consumption between occupied and non-occupied periods (Figure 9). During the monitored January – May period, about 40% of the consumption occurs in the workdays (7:00-18:00) and the remaining 60% during weekends and at night. Spot measurements made during one working day in summer yield opposite percentages: 61% (7:00-18:00) and 39% (rest of day). Extrapolating similar analysis performed in case study n. 3 in which a VRF system was monitored over several seasons with different operating schedules, savings on the order of 30% in annual chiller consumption may be expected in comparable climatic conditions. Figure 9. Daily electric consumption of central cooling plant: workdays and weekends Daily consumption, Chillers room 600 500
kWh
400 300 200 100
Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun
0
Case study 3: Long-term BMS monitoring of VRF heat pump system The case study concerns a XVII century building in Torino, which was almost entirely rebuilt after World War II. In 2006, a radical refurbishment of the building services has been completed by the ESCO in charge of the energy service contract and a new modular air-to-air VRF (Variable Refrigerant Flow) reversible heat pump system was installed, consisting of 16 external units and 150 fan coil internal units. Mechanical ventilation is provided to some areas only by five AHUs fed by air-cooled water chillers and gas-fired condensing boilers. A BMS performs complete monitoring and
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management of the building services (HVAC, fire prevention, security, lighting). Energy performance data acquired by the BMS have been recorded and stored since 2005. The data records indicate that, in the initial operation period, the HVAC system was running 24/24 hrs – 7/7 days; the operating schedule was subsequently optimized by introducing nighttime and weekend system set-back criteria. The effects are clearly seen in the graphs of Figure 10. The weekend setback is reflected in the greatly reduced consumption on Saturday and Sunday, and in increased system consumption on Monday; the night set-back determines an increase of the hourly energy demand in the morning period of working days. Referring to typical winter conditions, the following electric energy consumption reductions are achieved: 9% on working days and 85% on weekends, yielding a 26.7% weekly saving. The effects of modified system operation are also well visible in a carpet plot representing the time trend of total electric energy consumption (Figure 11): the plot on the left side refers to a period in which the operation schedule of the VRF system is well defined and stable, while the plot on the right side basically reveals a continuous operation, in which night-time or weekend setbacks are not clearly applied. Figure 10. Daily and hourly electric energy demand of VRF system with different schedules Daily consumption (14-20 Jan ; 15-21 Dec 2008)
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Case study 4: Effect of the operating schedule on a chiller electric consumption The case study considers a public building equipped with a two-pipe fan-coil system, installed at the time of building construction (1970), coupled to a gas boiler and water-cooled electric chiller; the latter unit was replaced in 2002 and is in good overall maintenance status. In consideration of the low thermal capacity of the building, the study was focused on assessing the effect of a reduced system operational schedule. An electric meter was installed on the chiller, to measure the hourly consumption; the chiller operates six days a week (at reduced load on Saturdays), while it is completely shut off on Sundays. Three different operating schedules, each applied for about four weeks, were adopted to investigate the effects of varying the chiller on-period: A: 11 hrs ON (7:00-18:00); B: 14 hrs ON (6:00-20:00); C: 10 hrs ON (7:00-17:00). The monitoring results are summarized by the three energy signatures of Figure 12, each referred to one of the chiller operation schedules. The temperature dependence of electric consumption is fairly linear, with acceptable correlation coefficients (particularly for schedules A and C), and exhibits comparable trends, ranked as expected for increasing operation ON-times. Taking into account the statistical distribution of temperatures, it that, by reducing the chiller operation time from 14 hrs/day (B) to 11 hrs/day (A), a 20.7% reduction of chiller mean daily consumption was
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achieved; a further reduction to 10 hrs/day (C) increased the savings to 22.1%. These values correspond to average savings of 6.2% per hour of daily operation reduction. Figure 12. Chiller electric consumption vs daily mean external temperature Energy Signature (schedule changing) 700 600
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Refrigeration equipment performance analysis The experimental analysis of water chiller or heat pump performance requires specific instrumentation which allows the measurement of the thermodynamic conditions of the refrigerant fluid and the electric input to the compressor and auxiliaries. The instrument that was used by the authors [7] is equipped with refrigerant fluid pressure gauges (compressor inlet and outlet) and temperature sensors (refrigerant temperature at compressor inlet / outlet, and condenser outlet; secondary water at condenser inlet / outlet); the temperature sensors are clamped on the fluid pipes, while the pressure gauges must be connected to the dedicated ports present in most refrigeration equipment. In addition, the instrument is connected to two power meters, to log the electrical consumption of up to two compressors. A data base of the thermodynamic properties of the refrigerant fluid is provided, yielding the refrigerant saturation temperature values corresponding to the measured pressures. This allows the determination of meaningful operative parameters, such as vapor superheating at the evaporator outlet, and fluid subcooling at the condenser outlet. For the estimation of the isentropic efficiency of the compressor, an assumption must be made on heat exchange in the compression phase. The above data make it possible to draw the actual thermodynamic cycle and to calculate the enthalpy difference between compressor inlet and outlet: based on this figure, and by estimating the electric and mechanical efficiencies of the compressor and motor, it is finally possible to determine the system COP and refrigeration flow rate, using the measured value of the electric energy consumption of the compressor motor. The above described instrument may therefore be employed both as an energy evaluation and diagnostic tool, for identifying system faults such as evaporator or compressor fouling, insufficient refrigerant charge, or poor compressor efficiency. These defects can be readily corrected with maintenance actions, therefore achieving significant energy savings [8]. Case study 4: Performance analysis of an open-loop water-condensed electric chiller The first analysis presented in this paper was performed on the electric chiller of case study n. 4. The unit assessed is a water condensed chiller, using underground water as the cooling medium. The unit consists of two refrigerant circuits, each including compressor and evaporator, connected to a single condenser. The compressors are of the reciprocating type, with multiple cylinders and suction and discharge valves, and can operate at two load levels, thus allowing four degrees of partialisation. Previous to the performance assessment, the HVAC system was inspected following the HARMONAC guidelines and inspection methodology. The inspection results, for the considered chiller, showed a good state of maintenance. No sign of oil leakages was detected. Prior to the test the unit was considered perfect. The assessment data (Figures 13), however, showed that some operating parameters were critical, and that the unit performance was not always satisfactory. Figure 13a shows the electric power input and the isentropic efficiency of the two compressors under different load conditions. Figure 13b shows, for the same operating conditions, the chilled water temperatures at the evaporator’s inlet and outlet, and the refrigerant fluid temperature in the two evaporators. Finally, Figure 13c indicates the two circuits COP and compression ratio. The experimental data reveal that:
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• At full load, the power input to compressor n. 1 (C1) is very close to its nominal value (39.45 kW), while the corresponding value for compressor n. 2 (C2) is about 10% lower; in terms of isentropic efficiency, C2 is about 5% more efficient than C1. At partial load, the performance difference between C1 and C2 is very small, both in terms of isentropic efficiency and input power (see Fig. 13a). Probably, the lower C2 performance at full load is caused by problems in the cylinders that are disconnected at part load. • Circuit 2 is likely to have a low refrigerant charge, which explains the lower evaporation temperature (around – 4°C, with risk of freezing at the water side, see Fig. 13b), and unstable COP values, caused by continuous flash evaporation (Fig. 13c); the same graph also indicates that C2 has a higher pressure ratio than C1. A correct charge would increase the evaporation temperature with an increase in COP on the order of 3-5%/K. • Other monitoring results (not shown in the graphs) also reveal an excessive superheat at the evaporator’s outlet, which may be corrected by adjusting or replacing the expansion valve.
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Case study 5: Performance analysis of an water-condensed chiller with evaporative tower The second analysis refers to the electric chiller of Case Study n. 5. The unit assessed is a water condensed chiller installed in 1996. The unit is composed by two refrigerating circuits, served by two compressors, two condensers and a single evaporator. The compressors are of the reciprocating type with multiple cylinders and suction and discharge valves. Results are presented in Figure 14. Figure 14. Case Study 5: Chiller parameters logged
The analysis shows that: 1. The ∆T in the evaporator between evaporation dew point and cool water outlet is very high, more than 10 K. A good system would have 3-5 K. The high value of the ∆T is probably caused by the high value of the superheat (12.4 K). Decreasing the value of the superheat appears to be a good solution to increase the temperature of evaporation. Experimental data indicate that for every degree of evaporation increase, the capacity and COP increase almost by 3-5% [7]. 2. The ∆T in the condenser between outlet gas temperature and condensing water outlet is very high, more than 10 K. A good value for a new condenser would be 2 K and an adequate value
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for an old condenser 6 K. It appears that the condenser is undersized or fouled. Experimental data indicate that for every degree over the mentioned ∆T, the system wastes 1-3% energy. 3. The compressor is working properly and is in good state, with a 67% efficiency. 4. The sub-cooling could be raised to 4-6 K (presently it is about 1.8 K), the evaporator will work better with this value. As a conclusion, the chiller COP would have been much better with higher evaporator and lower condenser temperatures, aimed at obtaining a lower pressure ratio. Of course, an adjustment of the expansion valve (TXV) is necessary, and a special attention should be paid to determining the new set point values, in order to avoid the vapor hunting instability. During spring 2010 the mentioned modifications will be implemented, and in the following summer the chiller will be monitored to measure the expected efficiency improvement. Conclusions The results obtained so far by the HARMONAC project have demonstrated that an effective approach to HVAC system inspection and energy auditing requires a sound basis of measured primary energy consumption data, which may be difficult to obtain when electrically-driven components are concerned. The availability of properly designed and installed BMS, in conjunction with the installation of a limited amount of relatively low-cost dedicated measurement equipment, is generally sufficient to obtain a clear picture of the energy performance of typical HVAC systems of tertiary buildings. Starting from the analysis of such data, simple ECOs (mostly related to system operation and maintenance) may be readily identified and implemented at very low or even negligible costs. The primary energy savings that such ECOs can yield are typically in the 5%-25% range, but may be as high as 60% under very favorable circumstances. Detailed on-site experimental analyses of chiller / heat pump performance require, on the other hand, fairly sophisticated equipment and a specific expertise in data interpretation. These analyses, however, are extremely helpful in determining typical equipment defects, such as low refrigerant charge, inefficient compressor, or fouled evaporator / condenser. Such defects may be readily corrected with maintenance actions, which may lead to significant energy efficiency improvements. Acknowledgements The results presented in this paper were produced in the HARMONAC project (contract EIE/07/132/SI2.466705) – project website http://www.harmonac.info References [1]
http://www.energyagency.at/projekte/harmonac.htm
[2]
Directive 2002/91/EC of the European Parliament and of the Council of 16 December 2002 on the energy performance of buildings. Official Journal L 001, 04/01/2003 p. 0065 – 0071.
[3]
Masoero M. and Silvi C. 2006. AUDITAC Technical Guides for owner / manager of an air conditioning system: Vol. 12 - Building Energy Management Systems control strategies for air conditioning efficiency. Can be downloaded at http://www.energyagency.at/projekte/auditac.htm
[4]
Masoero, M. and Silvi, C. A proposal for an energy conservation opportunities (ECO) list in auditing of air conditioning systems. Proc. Climamed 2007. Genova, 5-7 settembre 2007, pp. 897-912.
[5]
ASHRAE. 2009 Handbook of Fundamentals, Chapter 19 – Energy Estimating and Modeling Methods, Atlanta.
[6]
Jagerman, L and Olson, D. 2007. The EPBD and Continuous Commissioning. Final report of WP2 of Building EQ project. Can be downloaded at http://www.buildingeq-online.net
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[7]
Berglöf, K. Methods and Potential for Performance Validation of Air Conditioning, Refrigeration and Heat Pump Systems. Proc. Inst. Refr. 2004-2005.
[8]
Prakash, J. 2006. Energy Optimisation Potential through Improved Onsite Analysing Methods in Refrigeration. Master of Science Thesis, Masters Program in Sustainable Energy Engineering, Department of Energy Technology, Royal Institute of Technology (KTH), Stockholm, Sweden.
[9]
Bory, D. 2008. Analysis and Simulation of Defects of Operation for Air Conditioning Audit. PhD Thesis, Ecole des Mines de Paris.
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Image Processing for Overnight Lighting Quantification in Buildings Dr Neil Brown Institute of Energy and Sustainable Development, De Montfort University. Abstract For non-domestic buildings, the issue of the spread of unused office lighting has become topical, whereby a significant amount of electricity may be wasted, as suggested by initial surveys in London. In order to understand the extent of the problem, one approach involved night-time surveying of office buildings. The process of surveying buildings from the outside is laborious and expensive, and as such has been limited in the past to a small percentage of the national stock. This paper describes the application of time lapse photography and image processing for counting lit windows at night, in order to establish lighting usage patterns. Sample results are presented showing system performance, and illustrating the extent of unoccupied office lighting. These results also begin to validate the hypothesis that office lighting outside normal office hours in the UK is a prevalent waste of electricity, offering a considerable opportunity for energy savings. Introduction In UK non-domestic buildings, a significant amount of electricity may be wasted though unoccupied lighting, as shown by initial surveys in London [1]. The process of surveying buildings from the outside can be laborious and expensive, and as such has been limited in the past to a small percentage of the national stock. Lighting use patterns when compiled from measured energy meter data normally would only be possible through extensive sub metering at considerable cost, and as such, have also been limited to a small percentage of the UK national stock. Non-invasive instrumentation offers a key to understanding the extent of unoccupied lighting. This paper suggests the application of time lapse photography and image processing for rapid surveys of lighting in the non-domestic stock, in order to establish [unoccupied] lighting usage patterns. Background Energy consumed in buildings accounts for around 44% of UK CO2 emissions [2]. With concerns over global warming and climate change, building services have become a focus of attention. Building size, age, and glazing type can inform theoretical energy consumption, particularly for heating [3,4], but electricity use (e.g. lighting) is more carbon intensive than gas, yet often overlooked. One study, took after-hours ‘snapshot’ surveys from buildings to establish usage patterns of IT and office equipment [5]. This showed that from a sample of 1329 CRT monitors, the switch-off rate was only 32%. In an initial study on lighting, by H Bruhns at University College London, 140 West End office buildings in London were surveyed [1]. The sample included central city office buildings of varying ages, and sizes from office blocks to converted town houses. Daytime surveys established glazing, then each building was viewed twice between 10 pm and 3 am, and lit window percentages were found by counting. The surveys found 25% of lights on at 10pm falling to 17% at 2 am. These data were used to formulate 24 hour and full week lighting profiles of useful and wasted lighting use, showing that overnight and weekend lighting amounted to 23 – 30% of total lighting use. National electricity waste was estimated by extrapolating from these profiles to the UK, amounting to 1500 - 1900 GWh electricity, or 0.8 – 1.1 Megatonnes of CO2 per year, although this would assume that central London behaviour is replicated across the UK, and sample size would need to be increased to ensure accuracy. Research shows a 9% annual increase in electrical baseloads for Local Authority Buildings [6], a portion of which may be due to unoccupied lighting. Some efforts have been made to reduce unoccupied lighting in other countries: In Boston [7] in late 2008, lights in buildings above the 30th floor were extinguished as part of a trial to save electricity, from 11 pm and 5 am. In New York, improved building controls and conservation are cited as useful in reducing unoccupied lighting, but many companies’ buildings remain illuminated as status symbols [8]. An article describing a study of businesses in the City of London, estimated 200 kilotons of CO2 per year due to unoccupied lighting, equating to 15 – 20% of energy bills [9], although the survey methodology is not described. The European Climate Change Programme identified lighting as one use of energy with high potential for cost-effective reduction of greenhouse gas emissions, described in a 2005 directive [10]. Technical
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solutions such as automatic lighting controls, and more efficient lighting are more visible in new-build, and to a lesser degree refurbished buildings, but are still a very small part of the market [11]. It is clear that as policymakers legislate further for cuts in unnecessary energy consumption from lighting, there is a need for much more comprehensive and reliable data. This particular waste of energy in buildings has wider reaching effects on the built environment and wider society. No professional astronomers remain in the UK, although a community of amateurs remains, whose efforts are hampered by ‘sky glow’ [12]. Many children in urban areas are no longer familiar with the night sky because so little of it can be seen. Also, light pollution from tall buildings has been cited as a major cause of death to migrating birds [13]. Light pollution can seriously affect enjoyment of the environment, including disruption of sleep, and as such is now treatable as a statutory nuisance in legal cases [14]. A health issue exists since recent research indicates increased rates of certain cancers through disruption of melatonin production, one cause being light pollution [15]. In any case, it is clear that the scale of electricity wastage is potentially significant and must be investigated. A major difficulty in estimating the scale of the problem has been manually surveying buildings, compounded by night-time working. Time-lapse videos were made by the author of Canary Wharf (One Canada Square) in London E14, which houses around 20 businesses, and central Sheffield, in early 2007. It became clear from the Canada Square video that occupancy patterns were more complex than previously thought, with lights being switched on and off throughout the night. This suggests strongly that future studies require fine-grained data, with several samples per hour (which would not normally be practicable manually). It also suggests that distinct differences exist between lighting use patterns for occupied and unoccupied buildings, and ordinary occupancy hours vs. 24 hour operation. Time lapse photography Canon EOS -30D digital cameras were used in conjunction with TC80N3 external controllers, which can be set to trigger the camera shutter at preselected intervals, from seconds to hours in length. 1855mm zoom lenses were used, set to manual focus, with image resolution set to 8.2 megapixels, and 1GB memory cards used. Aperture and shutter speeds were set to automatic. Cameras were placed indoors, facing outwards through windows chosen for accessibility and view. It was found that battery life for the manufacturer’s rechargeable batteries was adequate for at least 96 hours’ use with a ten minute interval between shots. In order to shield the cameras from indoor lighting, a cardboard ‘hood’ was used (as shown to the right of figure 1), which was taped to the window.
Figure 1 - Camera setup
Video Analysis Initially a time lapse series of images can be converted into a short movie, e.g. in avi format, which was carried out using Jasc Animation Shop software. This enables basic manual analysis of night lighting usage patterns. Initially a time lapse series of images was taken of the skyline of Canary Wharf, looking southwards from the Bow Triangle (London E3), at a distance of around 2km. These images were taken on the morning of 27th January. Figure 2 shows a series of images extracted from the time lapse series of one building, show the uppermost 18 floors of No.1 Canada Square, London E14 (this tower is commonly referred to as ‘canary wharf’), which houses around 19 businesses. It was thought that many such buildings have lighting used all night, although the buildings may be unoccupied. As can be seen from figure 2, some activity is clearly visible even between 2.36 and 5.36 AM on certain floors. A complete floor can be seen to have the lighting cycled, and several windows change in intensity – This may be due, for example to deep plan office lighting use varying with respect to depth from the facing elevation. Certain floors however, remain constantly lit.
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Figure 2 - Time lapse photography of No.1 Canada Square
Image Processing – window identification In order to produce useful information which can be used to produce a model of night-time illumination, an automated count of illuminated windows can be used to provide lighting use profiles. For an evenly illuminated building (it is rare that a city building is not lit at night from the outside by light pollution) with distinguishable windows, as opposed to curtain walling, it was thought that the task of automatic window counting would be quite straightforward. A simple program (called an igraph) was written using WiT image processing software and is shown in figure 3. A directory of images is selected, and is fed into a sequencer. This is used to ‘pump’ the main code with the directory file names. The readObj operator is used to extract image data from files, whilst a counter keeps track of the number of images processed. A region of interest is extracted for processing, which is converted to a greyscale image. An automatic threshold of the image is taken based on the standard deviation of the pixel grey levels within the image. This produces a binary image, where pixel values of 1 = white, and 0 = black. Since window frames may give a false count, these are artificially ‘blurred’ using an erosion operator, which adds a ring of white pixels around each thresholded object. For cosmetic purposes (ease of visualisation), the resulting image is then eroded such that the identified windows may be superimposed on the original colour image. The ‘getblobfeatures’ operator then is used to identify the properties of connected regions (clusters of ones within the binary image). Output parameters include features such as area identified (blob) blob count, area, perimeter, and xy coordinates of centroid. For the purposes of demonstration, the blob area is utilised, and the count. Blobs (in this case, illuminated windows) are then superimposed upon the original colour image. Figure 4 shows the results of running this code on a sample image taken mid-evening on Friday 25th January. The output from the software is presented as three tiled images. From left to right we see the original image, followed by the binary image. The windows identified as lit may be seen to the right. As can be seen, there is a small degree of error whereby some windows which are lit have not been picked up by the processing algorithm. One difficulty realised with applying a threshold is that some parts of the image may be lighter than lit windows, for example walls illuminated by a streetlight. Figure 3 - Basic processing algorithm for single building
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Figure 4 - Apartment blocks, image, thresholded and lit windows identified
Processing method for large scenes A typical scene for processing is shown below in figure 5. In order to compensate for illumination of building surfaces, a lowpass filter is applied. This extracts ‘low frequency’ or gradually changing features from an image, such as a large dimly lit wall, or as can be seen in figure 5, a floodlit building such as the church towards the bottom left of the image. Also when imaging large scenes, image brightness can vary considerably from one part of the image to another. Adaptive thresholding was found to work for images of single buildings as shown in figure 4, but ease of use was limited by the need to provide a kernel to describe the area of image which would be averaged in order to produce the local threshold. Since the number of pixels representing each window varies considerably from one building to another. It was found that taking a moving average of the lowpass image produced a more stable result, compensating for shifts in illumination due to moonlight and varying cloud cover (figure 6). A highpass filter is used to extract high frequency data, as illustrated in figure 7. In practice, this means features which rapidly change with respect to x and y positions throughout the image, or small objects. The method effectively ‘amplifies’ lights and illuminated windows, and reduces larger features. Subtracting the lowpass image from the highpass image reveals lighting, with all building detail removed (figure 8). The image is then thresholded based upon standard deviation of the image pixel values, in order to produce a binary image such as that shown in figure 9. Blob analysis is then used to count visible lights, as can be seen in figure 10. Figure 5 - City of Sheffield night image
Figure 6 - Low Pass Filtered image (mono)
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Figure 9 - Thresholded image
Figure 10 - Automatic identification of lighting
Figure 11 shows the dataflows for the image processing and image feature extraction system. Image files may be interrogated in order to extract accurate timestamp data from images. Exchangeable image file format (EXIF) is a specification for the image file format used by digital cameras. The specification uses the existing file formats including JPEG and TIFF, with the addition of specific metadata tags. Matlab software version 7.5.0 was used to interrogate image files, using the Matlab function exifread to extract timestamp data. Timestamps were added to the textfiles of window counts provided by Wit, and the resultant data uploaded to a Mysql driven open source database for storage, and because of ease of use of Mysql’s functions for processing data by time and date. Figure 11 - Dataflows for image processing and feature extraction
Figure 12 shows the (graphical) code implemented in Wit for processing large scenes (with a feature to extract individual buildings) in more detail. The actual image processing part of the code is relatively small, with much code used for housekeeping. Code operation is described as follows. Upon start-up, the image directory is scanned and image names are loaded in to the software for scanning (A). Images are imported from JPEG files and converted to greyscale for processing (B). Daytime images are not useful for this particular analysis, but order to retain time stamps for plotting, all images are processed to be dropped at a later stage based on daylight levels. This may not at first appear to be efficient coding, but this code in the future may be used for identifying lighting which is used unnecessarily in the daytime. A region of sky is extracted from the image and a mean value taken, which is subjected to a hard threshold in order to separate night from day data. In practice, this has not required adjustment, and is set at 100 in the range 0-255 (8 bit pixel intensity, unit less). Daytime data is replaced with zeroes (L). The building under observation is selected using user input with a mouse, selecting a rectangular area (D). The mean total image brightness (E) has been found to work well for thresholding in conjunction with the combination of lowpass (where the kernel size is around 10x the largest window size), (F) and highpass (where the kernel size is smaller than the minimum expected window size), filtering (G). The image is thresholded and the binary image of the building is fed to an erosion operator (H). This cleans up any moderately blurred images to separate out individual windows at times of low visibility, such as during rain or fog. The blob features (features of connected regions) are extracted (J) and as a quality check, are plotted overlayed on the original greyscale image
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(K). Window counts are grouped and stored for plotting (L). Filenames are assembled and the resultant vector of window counts is saved to file (M). Figure 12 – Large Scene processing algorithm implemented in WiT
Survey Areas Sheffield Time lapse photographic surveys were carried out during the winter between Feb 1st and Feb 5th. Figure 13 shows the Sheffield University Arts Tower, where pictures were taken from an office window on the 18th floor, looking South East towards the City Centre (Figure 15), and North East towards the Kelham Island and Don Valley districts (Figure 16). Photographic surveys in Birmingham were taken from the 16th floor of the Chamberlain Tower, looking North towards the city centre, East and West areas (Figures 17 and 18 respectively). These photographs were taken from May 13th – 22nd. Photographs were taken at 15 minute intervals with fixed infinite focus, aperture and shutter speeds were set to automatic. Figure 13 University
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Figure 15 - Buildings in central Sheffield
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Results In order to check the accuracy of the image processing system when compared to human analysis, a number of time lapse images were manually checked. Referring to figure 19, the correlation between manual and automatic window counting for the London tower blocks illustrated in figure 4 is 93%. For non-domestic buildings also using the processing method for large scenes, correlation is slightly higher. Two examples shown in figure 18 are for office buildings in Sheffield (during Winter with poor visibility), and Birmingham (during Spring), scoring 93.3% and 97.4% respectively. Figure 19 - Manual window counting vs. image processing
Figure 20 shows a complete set of profiles for the photographic survey carried out in central Sheffield. Building numbers as shown relate to the areas outlined in figure 15. Some noise exists in profiles for the early hours of Saturday and Tuesday, which was due to a snowstorm, and fog. This would mean that the image processing system, at certain times, may underestimate the number of lit windows visible. Profiles have been sorted by peak numbers of visible windows for ease of viewing. The lighting profiles shown in figure 20 are for offices only, and are presented in a similar format averaged by broader time bands to more clearly show the differences in lighting use between weeknights and weekends.
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Figure 20 – Lighting profiles for buildings shown in figure 15
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Figure 21 - Week vs. weekend lighting averaged by time bands
Discussion and future work Imaging buildings from further away enables larger scenes to be surveyed during each time-lapse session, and consequently more buildings. Performance was affected by uneven image brightness across each image due to moonlight, cloud cover, and the intensity and clustering of illuminated windows themselves. The algorithm described in figure 3 was found to be greatly improved though the use of spatial filtering as described in the code shown in figure 12. Software run-times have been improved through the manual selection of the region surrounding each building, such that the whole scene does not need to be processed to find, e.g. image brightness. Typically the processing of 800 images takes one minute. The accuracy of the system was found to be 93% in a test with the basic algorithm (for close-up shots of around 200 metres). For tests on large scenes, with a range of up to 2 km, the lower result for accuracy was 93.3% and the higher was 97.4%. The time lapse method means that a surveyor is not required to work at night, with installation of the cameras taking around 30 minutes, and 15 for retrieval. The use of the post processing software offers significant time savings. Manually counting windows from images was found to take up to 10 seconds per frame, per building. The current image processing software counts at slightly higher than 130x this speed. Weather effects such as fog and snow can be seen to affect the performance of the imaging system, whereby the number of visible windows in a particular image may drop suddenly. A solution is to take images over a longer period. Using the equipment described, it was found that camera battery life and memory was adequate for surveys lasting at least 6 days. The use of a micro hard drive to extend camera memory capacity, and construction of an electronic controller to limit image taking to night time only may also be considered. What becomes apparent is that many buildings begin an evening with illumination approaching a peak, and in most cases, lighting is gradually reduced overnight, but not by a large margin. Referring to figure 21, the low rate at which lighting is reduced for offices during the course of the night is notable. It also becomes clear that lighting use has not dropped significantly at weekends between 24:00 and 02:00. Preliminary results are broadly similar to those suggested in [1], whereby drops in night time lighting use are low. Further time lapse photographic surveys are planned in order to build up a more accurate picture of night time and weekend lighting use, which will be the subject of a further paper. Conclusions The image processing system performance is comparable to that of a human observer, in its current iteration, with peak accuracy approaching 98%. Since the image processing system tends to underestimate the amount of lit windows, it is clear that data generated will not exaggerate the case for a reduction in unoccupied office lighting. Time savings are considerable, with no human intervention required at night, and off-line counting of illuminated windows enabled at greatly improved speeds. The system developed can give a broad picture of night time and unoccupied lighting use far more cheaply than, for example, sub metering of feeds for lighting circuits. Results validate manual surveys that show lighting use not to drop significantly outside business hours. The system described in this paper will be used to further explore the issue of lighting use in unoccupied buildings.
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Acknowledgements The original idea for surveying buildings externally to quantify unoccupied lighting came from Harry Bruhns, and early stages of the work formed part of Carbon Reduction in Buildings (CaRB) Consortium. CaRB has 5 UK partners: De Montfort University, University College London, The University of Reading, University of Manchester and The University of Sheffield. CaRB is supported by the Carbon Vision initiative which is jointly funded by the Carbon Trust and Engineering and Physical Sciences Research Council, with additional support from the Economic and Social Research Council and Natural Environment Research Council. The partners are assisted by a steering panel of representatives from UK industry and government. See http://www.carb.org.uk for further details. Apparatus was purchased as part of a grant from the Science Research Investment Fund (SRIF) from The Higher Education Funding Council for England. The author would like to thank Birmingham University Estates Department and Sheffield University School of Architecture for access to the viewpoints from which pictures were taken. References: [1]
Bruhns, H.R. Quantifying national electricity waste from overnight office lighting. Improving Energy Efficiency in Commercial Buildings (IEECB’08) Frankfurt, Germany, 10-11 April 2008.
[2]
DEFRA, DEFRA, e-Digest Statistics about: Climate Change. 2006. Department for Environment, Food and Rural Affairs, Customer Contact Unit, Eastbury House, 30 - 34 Albert Embankment, London, SE1 7TL, UK
[3]
Anon. International Survey of Building Energy Codes. Available http://www.greenhouse.gov.au/buildings/publications/pubs/international_survey.pdf. Department of Climate Change, 2 Constitution Ave, Canberra, ACT 2600, Australia.
[4]
Persson, M.-L. Windows of Opportunities: The Glazed Area and its Impact on the Energy Balance of Buildings. Available from: http://tinyurl.com/32j4mr. 2006. Doctoral thesis, Uppsala University, P.O. Box 256, SE-751 05 Uppsala, Sweden.
[5]
Webber, C. A. Roberson, J. A., McWhinney,et al., After-hours Power Status of Office Equipment and Energy Use of Miscellaneous Plug-Load Equipment. Energy, 31, 2823-2838, Nov 2006.
[6]
Carbon Reduction in Buildings (CaRB) project, EPSRC Grant Reference: GR/S94377/01, www.carb.org.uk. IESD, DeMontfort University, Leicester, LE1 9BH, UK.
[7]
Ross, C. Lights out, conservation on for city's tall towers. Boston Globe, September 3, 2008. Boston Globe,135 Morrissey Blvd. Boston, MA 02125, USA
[8]
Belson, K. Efficiency’s Mark: City Glitters a Little Less. New York Times, November 1, 2008.
[9]
Smith, L. Reporting the Global Action Plan study. The Times, November 18, 2006. Times Newspapers Ltd, 1 Virginia St, London E98 1XY, UK
[10]
Directive 2005/32/ec of the European Parliament and of the Council Establishing a Framework for the Setting of Ecodesign Requirements for Energy-using Products Amending Council Directive 92/42/eec and Directives 96/57/ec and 2000/55/ec. PE-CONS 3618/05, Strasbourg, July 6th, 2005.
[11]
Van Tichelen, P., Jansen, B. , Geerken, T., Vanden Bosch (Laborelec), T., VanHoof, V., Vanhooydonck (Kreios), L., Vercalsteren, A. Final Report Lot 8: Office lighting, Contract- TREN/D1/40-2005/LOT8/S07.56452) Preparatory Studies for Eco-design Requirements of EuPs. 2007.
[12]
House of Commons Science and Technology Committee. Light Pollution and Astronomy Seventh Report of Session 2002–03. HC 747-I, Published on 6 October 2003, by authority of the House of Commons, London: The Stationery Office Limited
from: 2008.
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[13]
Anon. Light Awareness Program to display birds killed in collisions with buildings. Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, M5S 2C6 Canada. http://www.rom.on.ca/news/releases/public.php?mediakey=aq6a5xuoy8
[14]
Morgan-Taylor, M. P., Light Pollution and Nuisance: The Enforcement Guidance for Light as a Statutory Nuisance. Journal of Planning and Environment Law, 1114-1127, 2006.
[15]
Pauley, S.M., Lighting for the Human Circadian Clock: Recent Research Indicates that Lighting has Become a Public Health Issue. Medical Hypotheses, 63, 588-596, 2004.
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HYDRONIC HEATING, VENTILATING AND AIR CONDITIONING Energy-conscious solutions for building occupant comfort
Tim Ashton, LEED AP, B.Sc. (Hons.) Physics for Advanced Technology Carrier Air Conditioning, Europe, Middle-East & Africa
Abstract Hydronic heating, air conditioning and ventilation systems offer a flexibility that makes them equally suitable for new building projects and for refurbishment of existing buildings. A wide range of equipment types is available making this type of system readily applicable for residential, commercial through to industrial applications, and often the choice of designers for offices, hotels and hospitals. The purpose of this paper is to provide an introduction and quantify the main energy-saving opportunities offered by such systems in the challenge to reduce the energy impact of buildings on the environment. The author includes concrete examples of the energy-saving opportunities available both at a component and system level, including detailed energy consumption analyses by making comparisons between a baseline application and systems that include energy-saving options such as automatic fan speed control, variable water flow and free cooling. Through these studies the author illustrates that communicating controls are key to taking energy saving beyond the component level and towards the HVAC system as part of an integrated building management system
Hydronic Heating, Ventilation and Air Conditioning (HVAC) solutions Introduction Hydronic HVAC solutions offer a reliable, flexible and ecologically considerate solution to meet the comfort requirements of today’s and tomorrow’s building users. With water as the primary fluid within the building to transfer energy to or from the spaces, hydronic solutions offer benefits that include minimising the amount of refrigerant and containing the refrigerant in a single component and location. This facilitates service, monitoring and maintenance operations and removes the refrigerant from the occupied building space, avoiding risk of contact with the occupants. Whatever the building type - from offices, commercial centres through to industrial warehouses - and for both new or refurbishment projects - hydronic systems offer architects, designers and end users a wide range of solutions to meet their particular application requirements and needs, provide occupant comfort and minimise operating costs. Many different hydronic solutions are available, including a number of water terminal based solutions such as fan coil systems, chilled ceilings and beams, water-to-air heat pumps and a wide range of air terminal based systems using diffusers. The choice will depend on a number of factors including customer preferences, building use and location, architectural features and investment available, to name but a few. All systems usually include one or more of the following main equipment types: liquid chillers/heat pumps, room terminal units, and air treatment/handling units. They offer the possibility to cool and/or heat and to provide controlled and treated fresh air volumes to the building. A standard or customised controls solution will complete the system and in the case of communicating controls will allow monitoring and control of the system to optimise occupant comfort and minimise energy consumption.
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Considerations for designing efficient hydronic systems Once a system has been selected a number of straightforward steps during the design stage will help to ensure that it delivers the best energy efficiency and performance 1. 2. 3.
Ensuring that the various equipment components offer best-in-class efficiencies, based upon an annual assessment of the building profile rather than just upon full load design criteria. Integrating energy saving measures that will offer building users a reduction in operating energy consumption with a return on investment. Incorporating communicating HVAC system controls to help the occupants manage their comfort whilst allowing the building manager to adapt operation based upon building use and real-time data. Efficient operation of the system is important whilst maintaining comfort conditions and/or design criteria as specified by the customer/user.
Hydronic systems offer a wide range of energy saving measures to help the designer achieve higher energy efficiencies, some of the more common ones are listed in table 1.
HVAC System controls
Terminal Unit controls
Piping distribution
Fresh/outdoor air plant
Room terminals
Production (Liquid chiller/heat pumps)
Table 1: Hydronic system energy saving measures by equipment type HVAC system component Produces hot or cold water for distribution via a pipe network through the building
Energy-saving opportunities Heat pumps/thermodynamic boiler for hot water production Chiller system with integrated free-cooling system and/or integrated heat recovery options
Conditions the air in the occupied space, heating, cooling, filtering and introducing pre-treated fresh/outdoor air quantities.
Communicating controllers (part of communicating system) Demand Control Ventilation (CO2 sensors) for certain areas (meeting and conference rooms) High-efficiency/low-energy motors (EC/DC) Heat recovery technology (plate heat exchangers, heat wheels) to recover waste heat/cool air from exhaust air to pre-treat entering air. Communicating controls allow strategies such as night-time free cooling to pre-cool buildings before occupied periods.
Basic functions include filtering, precooling and/or pre-heating outdoor air to provide neutral impact on the occupied space conditions. Treated air is supplied into building space via room terminal units or by independent means. Means by which hot and/or cooled water is provided to the various system components, traditionally using a constant-volume design.
Variable speed pump motor(s)allowing variable water flow to the distribution, offering pump motor energy savings at part load conditions.
Unit-mounted controls allowing space occupants to adjust the temperature set point and control the fan speed according to the terminal type.
Unit fitted with auto-fan mode control that adjusts fan speed to match space load requirements to economise fan motor energy by steps or variable speed.
Controls may be non-communicating or communicating and can be integrated into a larger Building Management System (BMS). Communicating controls offer connectivity with a central management system to adjust unit and system settings and performance to building requirements.
Use communicating controllers with a centralised management system. Benefits include: • management of occupied and unoccupied temperature set points • time scheduling of operating hours to match work days and holidays • monitoring and adjusting equipment operating conditions such as chilled water/hot water to match outdoor conditions and loads.
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Quantifying the potential of energy saving measures. One of the main challenges facing designers is to evaluate at the project design stage the potential savings associated with the various energy saving measures and resulting improvement in system efficiency. This is an important requirement to select the most appropriate measures and guide the design team and building owner on the energy savings and return on investment. The evaluation of an energy-saving measure is affected not only by building characteristics such as shape, building envelope characteristics, its geographical location in terms of the weather conditions experienced and its intended use. For example the benefits of integrating a free-cooling system will largely depend on the number of hours of building use during which the outdoor air temperatures are sufficiently low to provide free cooling to satisfy building requirement at that time. Consideration would need to be given to the measured gain of the free-cooling benefit and the energy used in running pumps and associated fans versus operating the conventional mechanical cooling equipment. One method available to estimate the potential savings is to use an industry-recognized HVAC design and simulation program* to evaluate the energy savings, and the remainder of this paper outlines the results of a study aimed at providing guidance for the more popular energy reduction measures for a commercial office building application at different locations throughout Europe. *All heating, cooling and ventilation load design calculations and subsequent energy simulation studies in this study were conducted using Carrier’s Hourly Analysis Program (HAP) version 4.31 - an HVAC design tool offering the capabilities of both design and energy simulation calculations within the same software program. All energy simulations are calculated for all 8,760 hours of the year using simulation weather data, operating schedules for the different days of the week, and the ASHRAE Transfer Function load method. Actual weather data is used to evaluate how the building's HVAC systems react to real sequences of weather over the course of a year whilst operating schedules define how heat gains vary on different days of the week.
Study description Often in the past HVAC systems installed in buildings of less than 2500 m² have been of a noncommunicating type with no centralised or BMS systems. The BASIC multi-client program building survey held in 2005 estimates that this building sector represents as much as 75% of all buildings built up to 2008, and hence this sector offers a significant opportunity to reduce building energy use and CO² emissions. As a result a two-story office building of 1380 m² surface area was chosen for the study and a building model defined covering all aspects of building envelope, internal loads, and occupancy schedule. Building characteristics The various characteristics defined and used building design and energy simulations, including thermal envelope characteristics, internal loads, occupancy schedules, thermostat setting and ventilation requirements are to be found in table 2 and figures 1 and 2. Table 2: Building envelope and internal loads INTERNAL LOADS
BUILDING ENVELOPE U= W/m²/K
R= m²•K/W
Walls
0.318
3.14
Main lighting type and power
Floor/foundations
0.27
3.7
Roof
0.685
1.46
Glazing
0.385
2.6
Task lighting (desk lights etc.) Electrical loads (PC, printers etc.) Outdoor air ventilation rates based on office requirement Activity level office work Sensible Latent
Structure
Occupancy (occupied spaces)
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12 m²/person Recessed, vented 12 W/m² 5 W/m² 10 W/m² 10.0 l/s/person 71.8 W/person 60.1 W/person
Figure 1: Occupancy schedule
Figure 2: Lights/electricity schedule
Choice of Heating Ventilating and Air Conditioning System The HVAC system chosen for the design and energy simulation studies is a 4-pipe ducted fan coil system with cooling supplied by an air-cooled liquid chiller and water for space heating provided by a gas boiler. A fresh air handling unit provides tempered outdoor air via the room fan coil units to serve the occupied spaces. The associated controls system was defined as a non-communicating type including manual user on/off fan coil unit controls with a single temperature set point thermostat. From an energy perspective such systems do not allow variation of thermostat set points for cooling and heating with occupied and unoccupied periods and holidays, thus this choice offered the opportunity to analyse the base system with a communicating system as part of the studies.
Study design and energy simulations method The approach taken in the study was to assess the impact of each energy-saving measure against the baseline building design on a component and system level. Note: Areas such as toilets with extractor fans, kitchens, restaurants etc. were excluded from calculations.
The baseline simulation results for the cooling and heating load based upon the chosen system is shown in figure 3 where the 8760 hours of data are shown in a scatter graph.
kW
Figure 3 HVAC system building load simulation 90 80 70 60 50 40 30 20 10 0 -15
-10
-5
0
5
10
15
20
25
30
35
40
Outdoor Air Temperature (dB°C)
Total Cooling coil load (kW)
Total Heating Load (kW)
The design and energy simulations were repeated for various major cities in different geographical locations keeping the same building model in order to evaluate the variation by location and weather conditions. An overview of the results for the annual design cooling and heating loads and the annual energy consumption for the different locations are illustrated in figure 4 highlighting the influence of geographical location and hence weather conditions with a clear swing from predominantly cooling in the south towards a more equally balanced requirement in the north.
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Figure 4: HVAC system total annual cooling and heating loads and power consumption simulations Annual Cooling Plant Load…
Annual Heating Plant Load…
Total Annual Power Consumption…
250 000
kWh
200 000
150 000
100 000
50 000
0 Athens
Rome
Madrid
Lyon
London
Brussels
Munich
Gothenburg
Six of the more popular energy-saving measures were chosen for the purpose of energy simulation studies and are listed in table 3. Each was individually simulated by location and compared with the baseline case, and a further study combining three of the more popular measures was also performed. Due to the quantity of data results it was decided for the purpose of this paper to present individually the energy-saving measure simulation comparisons for the location of Brussels in Belgium and to provide only overview for all the locations for the more common combinations as a summary. It is important to understand that the gain in efficiency at a component level should also be considered in terms of the impact at a system level and therefore results are presented for the individual component and from a system perspective. Table 3: Selected energy reduction measures by study Study
Description of energy-saving measure
Baseline
Traditional stand-alone non-communicating system, manual on/off fan coil controls and single set points
Study 1
Study 2
Terminal fan coil unit equipped with Auto fan coil unit fan cycling to meet space load. Separate temperature set points for both cooling and heating modes Temperature set point reset for OCCUPIED and UNOCCUPIED periods according to the building occupancy schedule. Use of an air-to-air heat recovery exchanger (50% efficiency) on the fresh air handling unit
Study 3
Variable-speed pumps for chilled water distribution.
Study 4
Use of a chilled water free-cooling system
Study 5
Use of a heat pump/chiller or thermodynamic unit to replace a traditional boiler.
Study 6
Fan coil units fitted with EC motors offering higher efficiency, reduced consumption and variable air volume control.
Study 7
Simultaneous use of the first three energy saving measures described in studies 1, 2 and 3.
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Study simulation results Study 1: Energy-reduction measure: Automatic terminal fan speed control, separate cooling and heating set points and centrally managed scheduling for occupied and unoccupied periods As described in the baseline case study many systems are equipped with non-communicating controls featuring manual type on/off or three-speed fan controls combined with single set point thermostats. Such systems do not allow management in line with building occupancy, with associated risks such as occupants leaving units operating all night. This study focused on the impact of incorporating fan coil unit controls that adapt fan speed to meet room loads and are able to communicate with a central management system to adjust thermostat set points according to occupied and unoccupied periods. The simulations show that significant energy savings are possible from reducing fan motor consumption at part load conditions and relaxing space temperatures when the building in not occupied. The study illustrates the potential savings found in the following areas: reduced cooling (33%) and heating loads (3%) with associated reductions in fan motor power (70%) and cooling (34%) and heating (19%) pump consumption. The overall system reduction comes to 19.4% against the baseline system. (Figure 5) Figure 5: Energy consumption by HVAC system component (kWh) compared with the baseline 200 000 173 067
180 000 160 000
139 448
140 000 120 000 100 000 72 027
80 000 60 000
69 668 67 764 48 591
Air Handling Unit
Terminal Fans
Cooling
Heating
7 859
6 390
-34%
Baseline
-19%
Pumps (Cooling)
Pumps (Heating)
-19%
8 490
Baseline
12 831
Baseline
-3%
Baseline
0
-33%
1 061
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3 530
-70%
7 152
Baseline
7 152
0%
20 000
Baseline
40 000
Total System
Study 2: Energy-reduction measure: use of an air-to-air heat recovery exchanger on the fresh air handling unit (50%) The function of the air handing unit in the system is to supply fresh air into the occupied spaces to meet occupant requirements, and the quantities supplied are covered by legislation. The fresh air supplied is usually pre-treated to be of neutral impact to space comfort conditions before it is supplied, often requiring some degree of cooling or heating according to prevailing external temperatures. An equivalent quantity of exhaust air must be extracted or expelled to avoid over pressurising the building through a return air ductwork system and building leakage. The use of a supply and return air handling unit incorporating a heat recovery exchanger can help achieve significant energy savings by recovering heat from the exhaust air to reheat the incoming
200
fresh air. Such a system also offers an opportunity to provide night-time free cooling during unoccupied periods whenever outdoor air temperatures are appropriate to pre-cool or maintain the building within comfort conditions The energy benefits include reducing the heating requirement for the heating plant to pre-treat the air and reducing the cooling plant demand at the beginning of occupancy periods. A number of technologies are available including heat recovery wheels, plate heat exchangers and run-around coils, with choice driven by factors including unit size, application and return on investment. In this study simulations are based upon a medium-cost solution of a plate heat exchanger of 50% efficiency, a choice that requires no additional motor or power for operation. The results of the simulations show reduced energy consumption in cooling (1%). The overall system saving in this case is amounts to 5.4% whilst the potential savings of such an energyreduction measure will likely increase with increasing application diversity.
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The results of this study are illustrated in figure 7 on the following page. Figure 7: System energy simulation for a variable water flow application 200 000 173 067
180 000
163 779
160 000 140 000 120 000 100 000 72 027 71 980 69 668 69 668
80 000 60 000
3 590
7 859
7 859
0,0%
12 831
Baseline
3 530
-72,0%
3 530
0,0%
7 152
Baseline
7 152
0,0%
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Baseline
40 000
Air Handling Unit
Terminal Fans
Cooling
Heating
Pumps (Cooling)
Pumps (Heating)
-5,4%
Baseline
Baseline
0,0%
Baseline
-0,1%
Baseline
0
Total System
Consideration should be given when combining variable-flow applications with other energy-saving measures such as chilled-water temperature reset, as under certain conditions these two energysaving solutions may work against each other, canceling out some of the energy benefits. For example under certain conditions increasing the chilled-water temperature may result in an inability to satisfy system demand with the result that the air system equipment components will increase air flow to meet demand with increased fan power consumption, canceling out some of the benefit. A Building Management System will help to prevent this by carefully monitoring and adjusting operating conditions to ensure maximum energy savings whilst maintaining occupant comfort. Study 4: Integration of free cooling within a chiller system
Hydronic solutions are compatible and lend themselves to what is commonly known as free-cooling solutions. Free cooling is the cooling of the chilled-water loop circuit to meet partially or fully the application requirements when outdoor air temperatures are sufficiently low, without mechanical operation of the chiller unit’s compressors. The potential energy savings from free cooling depend on a number of factors, including the application load profile (office or data centre for example) and the location of the project in terms of weather data. The load profile and the operating hours of the application will determine the number of hours with sufficiently low outdoor air temperatures to achieve free cooling. The opportunities for savings may be maximised if it is possible to use a chilled-water reset function. For example, if under certain load conditions or times of the year the HVAC system can still provide comfort using a higher chilled-water temperature than the design called for, for example from 7°C to 12°C, this could maximise the number of operating hours when free cooling may be used at low outdoor air temperatures. Two distinct free-cooling technologies are available on the market today, hydronic free-cooling or direct expansion (DX) free-cooling systems. In a hydronic free cooling system dry air coolers (usually for air-cooled chiller systems) or cooling towers (more usual with water-cooled chiller systems) are added into the cooling system pipe-work design. This design may require extra pumps, controls and the use of glycol to prevent freezing. The dry coolers or towers are operated to produce chilled water when the outdoor temperature is sufficiently low, thus avoiding the need to run mechanical plant. The use of a BMS system will assist in monitoring the operation and performance of the system and will help determine the overall efficiency and the relationship with the outdoor air temperatures. By measuring the resulting performance the building operator will be able to optimise the transition between free cooling, free cooling plus mechanical cooling and mechanical cooling only.
202
The direct-expansion (DX) free-cooling system offered by some manufacturers is integrated into the mechanical cooling unit(s) and offers benefits that include eliminating any additional pumps and controls, removing the need for glycol and saving on any extra space required with the hydronic system. For the simulations in this study a simplified assessment of the potential savings based upon a watercooled system with a constant chilled-water temperature set point and an integrated hydronic freecooling system. The results obtained (figure 8) show potential savings of as much as 26%. These savings are based upon an office application, and applications such as data centres where operation may be 24/7 will offer a considerably higher savings potential. Figure 8: System energy simulation savings potential for free-cooling application 30,00% 25,00% 20,00% 15,00% 10,00% 5,00% 00%
0,
ATHENS GREECE
ROME ITALY
MADRID SPAIN
LYON FRANCE
LONDON UK
BRUSSELS BELGIUM
MUNICH GERMANY
GOTEBURG SWEDEN
Free-cooling energy savings (%) over mechanical only system
Study 5: Use of a heat pump/chiller or thermodynamic unit to replace a traditional boiler Hydronic solutions have long offered the possibility to use a single unit, called a heat pump/chiller, to supply both cooling or heating water required for comfort conditioning according to the operating mode of the system. Such systems are known as 2-pipe changeover systems, and as simultaneous cooling and heating is not usually available, they are best suited to applications and climates where seasons and hence operating modes are distinct. The need for hot water for sanitary purposes combined with limited low outdoor air operating temperatures of heat pumps has often meant that boilers (gas, oil, fuel...) have fulfilled these requirements. Recently a new generation of dedicated heating heat pumps or thermodynamic boilers is available offering improved efficiency levels, higher hot water temperatures (63°C) and the possibility of operation at outdoor air temperatures down to -20°C. Designers now offer an energy-saving alternative in these products and installed in space heating and or sanitary hot-water production can offer substantially more energy-saving opportunities. The results of simulations compared with typical condensing gas boilers (90% efficiency) for the eight locations show potential savings of ~69-74% over a condensing boiler system (figure 9).
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Figure 9: Use of a heat pump/chiller or thermodynamic unit to replace a traditional boiler
75% 74% 73% 72% 71% 70% 69% 68% 67% 66% Savings %
Athens, Greece London Heathrow
Rome Italy Belgium, Brussels
Madrid Spain Munich, Germany
Lyon, France Goteburg Sweden
These results are possible with high-efficiency heat pumps offering Coefficients Of Performance (COP = output kW/input kW) ranging from 1.9 at -20°C to 4.6 at 20°C outdoor air temperatures, whilst supplying water at 40°C temperature, sufficient for space heating applications with fan coil units for example. The selection and choice of heat pump must be assessed considering the application heating requirements, site weather conditions and operating hours to determine, if the heat pump alone can satisfy the heating demand at all operating conditions or if some additional supplementary heating is required.
Study 6: Room terminal units fitted with EC motors The primary function of a water terminal unit is to ensure occupant comfort in the space, providing cooling, heating and in some cases fresh air, and a careful choice of unit type and installation (cassettes, ducted units etc.) should be made based upon the application needs and the room configuration to ensure good thermal comfort (temperature & air movement). Terminal room fan coils units are traditionally equipped with an alternating-current (AC) fan motor with an efficiency of ~55%, however increasingly products are available with direct current (DC)/electronically commutated (EC) motors with efficiencies of up to 90%. The first energy benefit of this type of fan motor is related to the reduced power consumption and improvement in ratio of air moved to energy consumed, decreasing from 0.8 W/l/s to 0.3 W/l/s. A second energy-related benefit concerns the possibility to provide variable air volume fan control, rather than a three-speed control, that allows the unit controls to better adapt air volume to the space load requirement, improving occupant comfort. This variable-speed fan operation offers energy savings in the same way as for variable pump speed control for cooling water distribution. As the maximum design loads for the fan coil units typically only occur for a limited period of the year, the variablespeed motor allows reduced fan speed at part loads and hence reduced power consumption. The theoretical savings due to part-load operation may not be fully achievable, as it remains essential to ensure good room air distribution to avoid discomfort from draughts, and the minimum turn down may also be limited by a legal minimum fresh air requirement for the space. A correct choice of air diffuser with excellent low air volume turndown characteristics will help maximise the possible savings, whilst still ensuring good air distribution in the occupied space.
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The study simulations against the baseline show a saving of 44% in fan motor power with a corresponding reduction in cooling coil load (0.7%) and a small increase in coil heating requirements (0.2%). The resulting system energy improvement in this study case amounts to 1.1% (Figure 10). This impact on cooling and heating coils sizing related to EC motors is a factor of their higher efficiency resulting in less motor heat being added to the air treated and delivered to the occupied space by the fan coil unit. In cooling mode this is a benefit reducing the theoretical cooling coil duty requirements whilst in heating mode this can result in an increase in heating coil duty. The overall balance will depend largely upon the hours spent in each mode. Figure 10: System energy simulation savings potential for room terminal units fitted with EC motors 200 000
173 067 171 086
180 000 160 000 140 000 120 000 100 000
72 027 71 539 69 668 69 831
80 000
1 962
12 831 12 745
7 859
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Air Handling Unit
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Heating
Pumps (Cooling)
Pumps (Heating)
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-0,7%
Baseline
0,2%
Baseline
-0,7%
Baseline
0
Total System
Study 7: Energy reduction measures 1 + 2 + 3 It is common to find more than one of the energy-saving measures implemented in an HVAC system the final study presented is the simulation of a system incorporating the first three energy measures: automatic terminal fan speed control, separate cooling and heating set points for occupied and unoccupied periods, the use of an air-to-air heat recovery exchanger in the fresh air handling unit and variable-speed pump chilled water distribution. The results of this study show that combined effects of applying energy-saving features 1, 2 and 3 to the same system achieve savings across terminal unit fans power, cooling and heating loads and pump savings that contribute to a system saving over the baseline case of 46% (Figure 11). Figure 11: System energy simulations based upon energy reduction features (1), (2) & (3) 200 000
173 067
180 000 160 000 140 000 120 000
93 814
100 000 80 000 60 000
69 668 48 387
Cooling
Heating
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6 087
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-23%
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-46%
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Baseline
2 468
-81%
Baseline
-70%
Air Handling Unit Terminal Fans
-59%
Baseline
0
12 831
Baseline
1 061
-33%
3 530
Baseline
7 152
0%
28 659 7 152
Baseline
40 000 20 000
72 027
Total System
Comparisons of results for major European locations The same selections of studies were simulated for each of the eight European locations and the results are compiled in figure 12. As illustrated the influence of the weather conditions for each location influence design heating and cooling requirements and the energy savings vary accordingly. However the opportunity to reduce energy consumption is clearly universal. Figure 12: Energy case study comparisons Study 1
Study 2
Study 3
Study 7
Terminals with auto-fan cycling, com municating controls with seperate cool & heat set-point & occupancy scheduling
Fresh Air Handling with heat recovery exchanger (50% efficiency)
Variable speed chilled water pumps
Combined effect of measures in studys 1,2 & 3.
0,0%
-10,0%
-20,0%
-30,0%
-40,0%
-50,0%
-60,0%
-70,0%
ATHENS, GREECE
ROME, ITALY
MADRID, SPAIN
LYON, France
LONDON, UNITED KINGDOM
BRUSSELS, BELGIUM
MUNICH, GERMANY
GOTHENBURG, SWEDEN
Conclusion Hydronic solutions offer an environmentally considerate solution with a wide range of opportunities to minimise energy consumption wherever there is a need for heating, ventilation and air conditioning and it is important to look at the opportunities from a system design perspective to correctly assess the overall energy-saving potential. The studies performed illustrate that significant economies may be delivered, whilst still offering systems primarily designed to satisfy human comfort requirements by designing in energy-saving measures. Whether in the form of variable-speed pumping systems that can adapt to building requirements, free cooling that takes advantage of prevailing weather conditions or by recovering heat generated by occupant activities and building use, hydronic systems show their flexibility to offer energy savings. Finally whilst sophisticated controls at equipment level are fundamental in ensuring that products deliver energy-efficient operation it is only through the use of communicating controls that the full extent of the energy-saving potential available can be realised through monitoring and dynamically adapting system operation and operating conditions to meet the building needs and reduce energy consumption even further. It is the belief of the author that whilst building design will become more energy-efficient, reducing the need for heating and cooling, that of ventilation will remain important. Hydronic systems with the energy-saving opportunities such as described in this study will continue to offer designers an opportunity to ensure occupant comfort in energy-conscious solutions.
206
References [1]
THE BENEFITS OF SYSTEM-BASED DESIGN Carrier Software Systems - Carrier Corporation Syracuse, New York, April, 2002
[2]
THE BENEFITS OF 8760 HOUR-BY-HOUR BUILDING ENERGY ANALYSIS - Carrier Corporation, Syracuse, New York, April, 2002
[3]
2005 BASIC multi-client program survey
207
A Systematic Optimization and Operation of Central Chilling Systems for Energy Efficiency and Sustainability Zhenjun Ma and Shengwei Wang Department of Building Services Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
Abstract: This paper presents an optimization strategy for optimal control and operation of building central chilling systems in order to minimize their energy consumption and provide improved control performance. The strategy is formulated using a systematic approach, in which the characteristics and interactions among the components and subsystems in the central chilling system are considered. The simplified models of major components are used in the strategy as the performance predictors to estimate the system energy performance and responses to the changes of control settings and working conditions. To ensure the models to provide reliable estimates when the working condition changes, the model parameters are updated online using the recursive least squares (RLS) estimation technique. A genetic algorithm (GA) is used to solve the optimization problem and search for globally optimal control settings on the basis of a cost function estimator defined. The performance of this strategy was tested and evaluated in a simulated virtual system representing the complex central chilling system in a super high-rise building under various working conditions. The model parameter identification and performance validation as well as the performance evaluation of the optimization strategy are presented. Keywords: Optimization strategy, systematic approach, central chilling system, performance model, parameter identification, energy saving
1. Introduction Building central chilling systems as major function of air-conditioning system often consumed about twenty-five to fifty percent of annual energy budgets in most air-conditioned commercial buildings [1]. Many studies have showed that well monitored and controlled central chilling systems have great potentials to help reduce the global energy consumption in buildings and improve the overall operational reliability [1-6]. In the last two decades, many efforts have been made on developing and applying optimal control strategies for building central chilling systems with an aim to enhance their operational performance [2-6]. For instance, a physical model-based supervisory control strategy for a direct-fired LiBr absorption chiller system was developed by Koeppel et al. [3]. Gibson [4] used artificial neural networks (ANNs) and genetic algorithms (GAs) to formulate an optimal control strategy for central chilling systems for energy efficiency. Ahn and Mitchell [5] presented an optimal control strategy for a cooling plant. The optimal control strategy was formulated using a quadratic regression equation. The results obtained from these studies showed that substantial amount of energy in central chilling systems can be saved when optimal control strategies are used. It is worthy noticing that most existing optimal control strategies for central chilling systems were developed using a model-based approach [2,3,5,6], in which different types of models were used to estimate system energy performance and response to the changes of control settings. When models are used in control systems, their prediction accuracy becomes essential. Since the working conditions of the models used in HVAC systems have no noticeable changes in finite time step or working range, the models (parameters of models) are only required to be accurate in limited working range. Therefore, the models can be reasonable simple and online learning and estimation approaches can be used to identify and update the model parameters to ensure the model accuracy when the working condition changes. The models using online learning and estimation approaches for parameters estimations are often called self-tuning models. Since new operation data are continuously used to estimate and update the model parameters, the prediction uncertainty of models can be reduced greatly. In the HVAC field, the importance of using self-tuning models in optimal control has been addressed in Ref. [7,8]. A number of model-based optimal control strategies combined the online parameter estimation techniques were also developed [6,9,10]. Farris and McDonald [9] presented an algorithm for applying advanced control concepts in HVAC systems. In order to utilize the optimal control
208
approach and obtain closed-loop control equations, a linearized system representation was used and the sequential least squares were developed for the parameter estimation. The user-adaptable comfort control for HVAC systems was described by Federspiel and Asada [10], in which the controller learns to predict the actual thermal sensation of the specific occupant by tuning parameters of the model of the occupant's thermal sensation and the model parameters were estimated using the RLS method. In the optimal control strategy for VAV air-conditioning systems developed by Wang and Jin [6], the adaptive finite-time incremental models of major components were used for performance prediction and the model parameters were updated using the RLS estimation with exponential forgetting. The results from above studies demonstrated that model-based optimal control strategies using online parameter estimation techniques taking into account the system dynamics can provide more reliable control and better energy performance. This paper presents an online adaptive optimal control strategy for centralized chilling systems. The optimal control strategy is formulated using a model-based approach, in which simplified physical models are used as the performance predictors and the model parameters are online continuously updated by using the RLS estimation with exponential forgetting. The optimization problem is solved by using a GA. The performance of this strategy is tested and evaluated in a simulated virtual environment representing the actual central chilling system in a super high-rise building. 2. Description of the Central Chilling System The central chilling system concerned in this study is a complex system in a super high-rise building in Hong Kong. Figure 1 presents the schematic of this central chilling system, in which six identical high voltage centrifugal chillers with the capacity of 7230 kW each at the design condition are used to supply the cooling energy for buildings. Each chiller is interlocked with a constant condenser water pump and a constant primary chilled water pump. A total of eleven cooling towers are used for heat rejection proposes. All cooling towers are an in house type and equipped with variable speed axial fans. Zones 3&4
From Office Floors
Zone 4
To Office Floors (S-B)
Zone 1
SCHWP-20 to 22
Zone 3
From Podium and Basement
From Office Floors PCHWP-14
(S-B)
HXZ4
PCHWP-15
HXZ4
PCHWP-16
(S-B)
SCHWP-11 to 13 SCHWP-17 to 19
Zone 2 HXZ1
HXZ1
To Office Floors
HXZ4
(S-B)
To Podium and Basement
SCHWP-14 to 16
From Office Floors To Office Floors PCHWP-07
PCHWP-08
(S-B)
HXZ34
HXZ34
PCHWP-09
PCHWP-10
HXZ34
PCHWP-11
HXZ34
PCHWP-12
HXZ34
PCHWP-13
HXZ34
HXZ34
SCHWP-06 to 10
SCHWP-01 to 02
PCHWP-01
WCC-01 (7230 kW)
EVAPORATOR
COOLING TOWER 2
COOLING TOWER 3
COOLING TOWER 5
CDWP-04
COOLING TOWER 6
COOLING TOWER 7
PCHWP-06 EVAPORATOR
WCC- 05 (7230 kW)
CONDENSER
CONDENSER
CDWP-03
COOLING TOWER 4
EVAPORATOR
WCC-04 (7230 kW)
CONDENSER
CDWP-02
PCHWP-05
EVAPORATOR
WCC-03 (7230 kW)
CONDENSER
CDWP-01
PCHWP-04
EVAPORATOR
WCC-02 (7230 kW)
CONDENSER
COOLING TOWER 1
PCHWP-03
PCHWP-02
EVAPORAROR
(S-B)
(S-B)
SCHWP-03 to 05
COOLING TOWER 8
WCC-06 (7230 kW)
CONDENSER CDWP-06
CDWP-05
COOLING TOWER 9
COOLING TOWER 10
COOLING TOWER 11
Figure 1 Schematic of the centralized chilling system. The secondary chilled water system is divided into four zones to avoid the chilled water pipelines and terminal units from suffering extremely high pressure. Only Zone 2 is supplied with the secondary chilled water directly. For the other three zones, the heat exchangers are used to transfer the cooling energy from low zones to high zones to avoid the high water static pressure. Zone 1 is supplied with the secondary chilled water through the heat exchangers located on the sixth floor. Zone 3 and Zone 4 are supplied with the secondary chilled water through the first stage heat exchangers (HXZ34) located on the 42nd floor. Some of the chilled water after the first stage heat exchangers is delivered to Zone 3 and some water is delivered to the second stage heat exchangers (HXZ4) located on the 78th floor. All pumps in the secondary water system are equipped with variable frequency drivers for energy efficiency except that the primary chilled water pumps dedicated to the heat exchangers in Zones 3&4 are constant speed pumps. 3. Formulation of the Optimal Control Strategy
209
3.1 Outline of the optimal control strategy Since Zone 1 of the building covers all possible control issues in the secondary chilled water system, the optimal control strategy presented in the following is only focused on Zone 1 in order to reduce the complexity of the control system. Figure 2 illustrates the overall optimization process of the optimal control strategy. It mainly consists of a rule-based supervisor, a GA optimizer, a cost function estimator, performance predictors (i.e., performance models) and model parameter estimators as well as system operating constraints. The control settings optimized include the condenser supply water temperature set-point (Tw,cd,set), chiller (chilled) supply water temperature set-point (Tw,ch,set) and heat exchanger supply water temperature set-point (Tw,hx,set). Here, the heat exchanger supply water temperature refers to the outlet water temperature at the secondary side of heat exchangers. The models used include a simplified chiller model, a heat exchanger model, a fictitious global AHU coil model and a cooling tower model. The model parameter estimators adopting the RLS estimation technique with exponential forgetting are used to identify and update the parameters required by these models using the online measurements. A GA optimizer is used to solve the optimization problem and seek the most energy efficient control settings on the basis of the cost function estimator and performance predictors. The operating constraints give the upper and lower limits of the control settings to be optimized. The rule-based supervisor is used to provide the final control settings for the real process based on the compromise of the control stability and energy savings, according to a set of rules defined. When cost saving is significant, the optimal control settings identified by the GA optimizer will be used to update the current settings. Otherwise, the control settings remain unchanged. It is worthy noticing that the operating number of the heat exchangers and variable speed pumps in the secondary side of heat exchangers in Zone 1 are optimized simultaneously during the model prediction process in each GA trial computation. This is because they are controlled based on the water flow rate in the secondary side of heat exchangers in this study. Operation data
Operation
Model parameter estimators Necessary
data inputs Real process Rule-based of the central supervisor chilling system Control Optimal settings settings
GA Optimizer
Updated model parameters
Trial settings Cost
Cost function estimator
Settings Cost
Performance predictors
Search ranges
Operating constraints Operation data
Figure 2 Optimization process of the optimal control strategy. The objective function for the system under investigation (only Zone 1 is considered in this study) is illustrated in Equation (1). Since the GA used in this study [11] intends to search for maximum values while the optimization problem is to seek the minimum energy consumption, the GA fitness function is therefore defined as Equation (2). J (T w, set , i ) = minW tot = min(W ch, tot + W ct , tot + W pu , tot ) (1)
(
) J (T 1 ) w, set ,i
f Tw,sup, i =
(2)
where, J is the cost function, f is the fitness function, T is the temperature, W is the power consumption, and subscripts w, ct, pu, ch, set and tot represent water, cooling tower, pump, chiller, set-point and total, respectively. To ensure the system to operate properly, a set of system operating constraints are considered. The input frequencies of variable speed pumps and cooling tower fans are constrained between 20 Hz and 50 Hz. To avoid low chiller (chilled) supply water temperature set-point causing the problems of ice in evaporators and the low efficiency of chillers, and high chiller supply water temperature set-point resulting in the problems of the humidity control for the air-conditioned spaces and inadequate cooling load provided, the chiller supply water temperature set-point is constrained between 5.0°C and 9.5°C. Taking into account the actual heat transfer performance of heat exchangers, the heat exchanger supply water temperature set-point is constrained between 5.5°C and 10.0°C. To avoid low condenser supply water temperature set-point causing low pressure problems in chillers, a low limit of 18.0°C is constrained as well.
210
3.2 Description of the performance models To ensure robust and reliable control performance, a series of semi-physical models are used in this study. The parameters in these models are considered to be slowly-varying, and be constant within a limited working range. All models used are linear in the parameters directly or linear in the parameters after through the logarithm transformation. The RLS estimation technique with exponential forgetting can be used to online identify and update the parameters required by the models to ensure the models to provide reliable estimates when the working condition changes. The details of the models used are presented as follows. 3.2.1 The fictitious global AHU coil model A fictitious global AHU coil is assumed to represent all AHU coils in the entire zone (Zone 1) of the central chilling system under study. Given the air inlet and outlet temperatures, humidity, water inlet temperature and air flow rate, the global AHU coil model is used to predict the required chilled water flow rate in the entire zone and the chilled water outlet temperature from the AHU coil. The total heat transfer rates on the water side and air side are computed by using Equations (3) and (4), respectively. The heat transfer coefficients at the water side and air side are assumed to be related with the water flow rate and air flow rate only and computed by using Equations (5) and (6), respectively. To identify the model parameters of • w, • a, • w and • a, both heat transfer coefficients in the water side and air side need to be calculated based on the inlet and outlet air and water states of the coil. Using the heat transfer coefficients calculated at the current and former sampling instants, the RLS estimation is used to estimate and update the parameters of the coil model. Qtot = UAw (Tb − Tw,in ) (3) Qtot = UAa (ha , in − hb )
(4) UAw = γ w (mw ) β w UAa = γ a (ma )
(5)
βa
(6) Where UA is the heat transfer coefficient, Q is the heat transfer rate, Tb is the equivalent coil surface temperature, hb is the saturated air enthalpy at the temperature Tb, • and • are the model parameters to be identified, and subscript in represents inlet. 3.2.2 Heat exchanger model In this study, the performance of the water-to-water heat exchanger with counter flow is modeled using classical ε-NTU method. The actual heat transfer in the heat exchanger is computed using Equation (7). The overall heat transfer coefficient is computed by Equation (8), which is considered as a function of the water flow rate in the secondary side of heat exchangers. There are three parameters (b0-b2) in this model. To identify these parameters, the heat transfer coefficient needs to be calculated based on the inlet and outlet water temperatures and the water flow rates in both sides of heat exchangers. Using the coefficients calculated at the current and former two sampling instants, the RLS estimation is then used to estimate and update the parameters in the heat exchanger model. Q = ε ⋅ Cmin ⋅ (Tw, s ,in − Tw, p ,in ) (7) UA = b0 + b1M w, s + b2 M w2 , s (8) Where C is the capacity flow rate, • is the heat transfer effectiveness, and subscripts s and p represent secondary side of heat exchangers and primary side of heat exchangers, respectively.
3.2.3 Chiller model The chiller model used in this study is a simplified physical model developed previously [12]. In this model, a fictitious refrigeration cycle, as shown in Figure 3, is assumed to simplify the complicated thermodynamic processes occurred in the refrigeration systems. The overall heat transfer coefficients of the evaporator and condenser (UAev, UAcd) are represented empirically as in Equations (9) and (10), respectively. The actual chiller power consumption (Wcom) is computed based on a fictitious power consumption (Wfic), as in Equation (11). There are nine parameters (C1-C9) that need to be identified in this model.
211
Pressure Pcd
Qcd = Qev + Wcom 3
2’
3’
2
Wcom Pev 1’
4 4’
1
Qev
Enthalpy
Figure 3 Illustration of the fictitious refrigeration cycle (Actual cycle: 1-2-3-4; fictitious cycle: 1'2'-3'-4'). To identify the parameters of C1-C6, the overall heat transfer coefficients of the evaporator and condenser need to be calculated based on the evaporator cooling energy and measured compressor power consumption together with the calculated evaporator and condenser logarithm mean temperature differences. To identify the parameters of C7-C9, the fictitious power consumption (Wfic) needs to be calculated based on the condensing temperature and evaporating temperature by using the fictitious refrigeration cycle. Using the heat transfer coefficients and fictitious power consumptions calculated at the current and former two sampling instants, the RLS estimation technique is used to estimate and update the parameters of the chiller model. 1 − 0.8 − 0.745 C1M w, ev + C2Qev + C3 = UAev (9) 1 C4 M w,cd − 0.8 + C5 (Qev + Wcom )1 / 3 + C6 = UAcd (10) 2 Wcom = C7 + C8W fic + C9W fic (11) 3.2.4 Cooling tower model In this study, a simplified model developed by Lebrun et al. was used [13]. In this model, the cooling tower was treated as an equivalent heat exchanger and modeled using classical ε-NTU method. The heat transfer coefficient of the cooling tower is simulated using Equation (12), where cp,a is the air specific heat and cp,af is the fictitious air specific heat which is computed by using Equation (13). Through the logarithm transformation, Equation (12) can be linear in the parameters. To identify the model parameters of Do, m and n, the heat transfer coefficient of the cooling tower needs to be calculated based on the inlet and outlet air and water states and calculated heat rejection capacity. Using the heat transfer coefficients calculated at the current and former two sampling instants, the RLS estimation technique is used to identify and update the model parameters. Mw m M a n c p , af ) ×( ) × (12) UA = D0 ( M w, des M a , des c p, a c p , af =
ha ,out − ha ,in Twb ,out − Twb ,in
(13)
3.2.5 Pump and fan models The power inputs of the cooling tower fan and secondary water pump are modeled to be approximately proportional to their flow rates cubed as in Equation (14) when the changes of the flow rates are small in a finite step or working range. Since the power consumption (W) and flow rate (M) are measured, the parameter (• ) can be learnt and estimated directly by using Equation (15) and updated at each sampling instant. W = λM 3 (14)
λk =
Wk ( M k )3
212
(15)
4. Performance Tests and Results Analysis 4.1 Test platform and test conditions A simulated virtual system representing the actual central chilling system under study was used as the test platform of the optimal control strategy. This simulated virtual system was constructed based on a transient simulation program TRNSYS. The local control strategies used in the simulated virtual system are as follows. The chillers were sequenced based on their design cooling capacities considering one constant primary chilled water pump and one constant condenser water pump dedicated to one chiller in this system. The operating number of the cooling towers was controlled based on the operating number of the chillers. The operating speeds of variable speed pumps at the secondary side of heat exchangers are controlled by maintaining the pressure difference of the critical loop at a predetermined constant value. A cascade controller, as illustrated in Figure 4, was used to control the operating speeds of the variable speed pumps at the primary side of heat exchangers by maintaining the outlet water temperature at the secondary side of heat exchangers at its set-point. Secondary side of HX
Primary side of HX
From terminal units HX To terminal units
M T
M T TT
HX
Temperature Temperature controller set-point
Water flow set-point
From primary system To primary system
Water flow controller
Figure 4 The speed control of variable speed pumps at the primary side of heat exchangers. 4.2 Performance test and validation of the performance models Since the accuracy of the performance models directly affects the performance of the optimal control strategy, the performance of major component models is validated firstly. In order to save the page size, only the validation results of the chiller model are presented.
Chiller power consumption (kW)
Figure 5 and Figure 6 show the comparisons between the model estimated and online ‘measured’ instantaneous power consumptions of the chiller when using different forgetting factors to update the model parameters. It can be observed that large deviations between the estimated and ‘measured’ values were existed when the forgetting factor used is 0.9998. However, good agreements between the two set of values can be found when the forgetting factor is changed to 0.993. Therefore, the selection of the forgetting factor is important for online parameter identification. The response of the RLS estimator to the change of the system characteristics can be accelerated by reducing the value of the forgetting factor, but a too low value might cause unstable estimation of the coefficients. The above test results showed that the chiller model combined with the RLS estimation technique with exponential forgetting can provide satisfactory performance prediction and are reliable for online control applications. 1200
Measured value Estimated value
1000 800 600 400 200 0 0
6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96
Time (hour)
Figure 5 Comparison between the estimated and ‘measured’ power consumptions of the chiller (Forgetting factor: 0.9998).
213
Chiller power consumption (kW)
1200 1000 800 600 400
Measured value Estimated value
200 0
0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96 Time (hour)
Figure 6 Comparison between the estimated and ‘measured’ power consumptions of the chiller (Forgetting factor: 0.993) 4.3 Performance test and validation of the optimal control strategy The performance of the proposed control strategy is tested and evaluated by comparing with that of a conventional control strategy. In the conventional strategy, the chiller and heat exchanger supply water temperature set-points were set to be constant, and the design temperature set-points of 5.5°C and 6.3°C were used, respectively. The condenser supply water temperature set-point was set using the fixed approach control method. In this study, the design approach of 5.0°C was used. During the tests, the sampling interval and prediction period used in the proposed strategy were 60s and 300s respectively, and the simulation time step of the virtual system simulation was 60s.
Supply water temperature set-point (°C)
Figure 7 present the profiles of the optimal temperature set-points searched by the proposed strategy for the typical mild-summer day. It can be found that all three temperature set-points searched were not constant but varied significantly during the day, and the differences between the chiller supply water temperature set-point and the heat exchanger supply water temperature set-point were varied significantly as well instead of maintaining at a constant value. It is also noted that the optimal chiller and heat exchanger supply water temperature set-points reduced greatly around 5:00am. This was caused by increasing an additional heat exchanger and an additional variable speed pump after heat exchangers in operation in that period. In the meantime, it is interesting to notice that the searched condenser supply water temperature set-points were increased greatly around 5:00am although the operating of heat exchangers and secondary water pumps has no direct impacts on the cooling tower system. The above results further demonstrated that the subsystems in central chilling systems are highly interactive and the systematic optimization rather than local optimization can help to minimize the overall system running cost. 27 24 21
Condenser Chiller Heat exchanger
18 15 12 9 6 3 0 0
2
4
6
8
10
12
14
16
18
20
22
24
Time (h)
Figure 7 Profiles of the optimal temperature set-points in the typical mild-summer day. Table 1 summarizes the energy consumptions of the central chilling system (only Zone 1 is considered in this study) in the typical mild-summer day by using the settings provided by the two control strategies. Since the constant condenser water pumps and constant primary chilled water pumps consumed relatively constant power consumptions, their energy consumptions were not included. Compared with the conventional strategy using traditional settings, the proposed strategy using optimal settings saved 390.7 kWh (1.35%) energy in the typical mild-summer test day. This part of
214
energy saving was achieved through applying the optimal control algorithm only and without adding any additional cost. Table 1 Energy consumptions of the central chilling system when using different strategies Control strategies
Conventional
Proposed
Energy consumption of cooling towers (kWh)
3639.5
3141.7
Energy consumption of chillers (kWh)
21597.3
21421.8
Energy consumption of pumps (kWh)
3602.9
3885.5
Total energy consumption (kWh)
28839.7
28449.0
Energy saving of cooling towers
-
497.8
Energy saving of chillers
-
175.5
Energy saving of pumps
-
-282.6
(kWh)
-
390.7
(%)
-
1.35
Total saving
Based on the above results, it can be found that the proposed optimal strategy, which considers the characteristics and interactions among and within the subsystems in central chilling systems, is more energy efficient and cost effective, as compared with the control strategy using traditional settings. 5. Conclusions A model-based optimal control strategy for centralized chilling systems is presented. This strategy is formulated by using the simplified performance models and a GA optimizer. To ensure the model accuracy, the RLS estimation with exponential forgetting was used to estimate and update the parameters required by the models using online measurements. The performances of the performance models and the optimal control strategy were tested and evaluated on a simulated virtual system representing the actual central chilling system in a super high-rise building. The results showed that the performance models combined with the RLS estimators can provide good performance in prediction. The test of the optimal control strategy showed that this strategy is capable of optimizing the overall system performance. Compared with a conventional strategy using traditional settings, this optimal strategy can save about 1.35% daily energy of the central chilling system. Acknowledgement The research work presented in this paper is financially supported by a grant of the National 11-5 program of PRC and a grant from The Hong Kong Polytechnic University (G-YXlZ) as well as the support from Sun Hung Kai Real Properties Limited. Nomenclature Symbols b0-b2
coefficients
C1-C9
coefficients
D0
coefficient
C
mass flow rate capacity, kW/K
cp,a
the air specific heat, kJ/( kg·K)
215
cp,af
the fictitious air specific heat, kJ/( kg·K)
f
fitness function
h
enthalpy, kJ/kg
hb
the saturated air enthalpy at the temperature Tb, kJ/kg
J
cost function
M
flow rate, kg/s
m, n
coefficients
Q
heat transfer rate, kW
T
temperature, °C
Tb
the equivalent coil surface temperature, °C
UA
overall heat transfer coefficient, kW/K
W
power consumption, kW
Greek symbols • ,• , •
coefficients
•
heat transfer effectiveness
Subscripts a
air
cd
condenser
ch
chiller
com
compressor
ct
cooling tower
ev
evaporator
fic
fictitious
hx
heat exchanger
in
inlet
p
primary side of heat exchangers
pu
pump
s
secondary side of heat exchangers
set
set-point
216
tot
total
w
water
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Evaluation of energy savings related to building envelope retrofit techniques and ventilation strategies for low energy cooling in offices and commercial sector Laurent Grignon-Massé, Dominique Marchio, MINES ParisTech Marco Pietrobon, Lorenzo Pagliano, Politecnico di Milano - Energy Department - End-use Efficiency Research Group
Abstract The energy savings achievable in the end-use space cooling depend on a number of variables related to the building envelope, the plants and to some extent the behavior of occupants. They are hence complex to evaluate and consequently often underrepresented in designers, energy managers and policy makers decisions. This paper is based on some results of the European Commission supported project KeepCool2. It discusses a methodology for bottom-up assessment of the energy savings related to “sustainable summer comfort” solutions: to do this, reference base case building typologies in offices and commercial sector are analyzed in 5 European typical climates, and dynamic simulations are used to calculate the reductions in the energy needs for cooling which can be achieved by specific retrofit actions (e.g. additions of effective solar protections, increased thermal insulation, day-time and nighttime mechanical ventilation, natural ventilation, low solar absorbance surfaces and others); also thermal comfort conditions in the analysed base cases are evaluated by using Fanger model and Adaptive ones, according to the European standard EN15251. Conducted dynamic simulations also allow evaluating the effects on energy consumptions of the interactions between several considered energy efficiency improvement actions. By using the developed methodology, we show typical values of energy savings related to single or packaged technical measures of sustainable summer comfort applied to typical building, in typical European climates. The adoption of different types of shadowing devices and relative manual and automatic controls and the use of adequate ventilation strategies show great potential in energy savings for cooling.
Introduction One of the fastest growing sources of new energy demand is space cooling. The studies EECCAC and EERAC predict a four-fold growth in air-conditioned space between 1990 and 2020 [1]. The IEA Future Building Forum even named cooling as one of the fastest growing sources of new energy demand (International Energy Agency, 2004). In its preamble, the European Energy Performance of Buildings Directive (EPBD) states that “Priority should be given to strategies which enhance the thermal performance of buildings during the summer period. To this end, there should be further development of passive cooling techniques, primarily those that improve indoor climatic conditions and the microclimate around buildings” (European Communities, 2003, p. L1/66) [5]. But such passive cooling technologies, which are already available and cost effective (such as the use of well designed sun shades, efficient lighting and office equipment, passive cooling via thermal exchange with the ground, night ventilation, etc.), are not widely used on the market today: the most common choice for a building owner when addressing summer comfort issues is still mechanical cooling, often without previously investigating other available measures regarding the optimization of envelope features (e.g. solar protections, glazing solar factor, thermal insulation of opaque surfaces, thermal mass). Only a limited number of retrofit actions taking into account passive cooling options have been documented in detail [2]. This paper is based on some results of European Commission supported project KeepCool2 (KC2 in the following) to contribute to a broad market transformation from “a cooling approach” to “a sustainable summer comfort approach”.
Sustainable summer comfort solutions: a methodology for the assessment of potential savings in existing buildings One of the KC2 objectives consists in developing an approach for a bottom-up assessment of the energy savings related to sustainable summer comfort solutions. The main results of this work will be “benchmarks” of gross annual energy savings related to typical existing buildings and to single or packaged technical measures of sustainable summer comfort. These results could be useful both for actors of the field (engineers, building designers, etc.) and national public authorities. Indeed, this quantified information will allow comparisons between summer comfort solutions, determination of the most efficient solutions as well as a possible evaluation methodology for energy savings as input to National Energy Efficiency Action Plans.
Overview of the methodology Scope of the methodology It has been decided to focus on existing buildings and on technical Energy Efficiency Improvement (EEI) actions which are defined as technical actions taken at an end-user’s site (or building, equipment, etc.), but not necessarily by the end-user himself, that improve the energy efficiency of the energy end-using facilities or equipment, and thereby save energy. An end-use action can be taken individually and evaluated separately (e.g. installation of solar shading). Behavioural or organizational actions (e.g. increase of temperature set-points) will not be treated in this analysis. The main objective is therefore to provide benchmark of energy savings implied by the implementation of EEI actions (relative to summer comfort) in European existing buildings. Main steps The assessment of energy savings related to summer comfort solutions is based on three main steps that are presented with more details in the following sections: - Definition and specification of reference cases: since the work consists in an ex-ante evaluation, we have chosen to base our approach on building simulations. Then, it is necessary to define reference cases (i.e. buildings considered as representative of the European building stock) to which summer comfort solutions will be applied and assessed. Furthermore, it is also necessary to define several climatic areas for Europe in order to reduce the number of building simulations. - Selection of technical solutions suitable for a quantitative assessment: EEI actions and packages of EEI actions that are worth to be studied (enough knowledge is available for their assessment, available on the market, etc.) are determined along with buildings suitable for these actions. - Evaluation of energy savings: this builds up on the two previous steps by evaluating the energy savings related to the implementation of a given (package of) sustainable summer comfort solutions in the predefined typical reference base cases. This third step requires the development of a methodology and set of hypothesis presented in this paper. Base case determination Definition of climatic areas Assuming that solar radiation and cooling degree days are the key parameters regarding summer severity, the global solar radiation has been summed and cooling degree days have been calculated over a year for 30 European cities: at least one city per EU 25 country and several cities for France, Italy and Spain. Furthermore, the severity of winter is also an important parameter in our study: on the one hand this has an important impact on building characteristics and on the other hand, the improvement actions we are going to study also impact heating energy needs. Buildings will be simulated in 5 cities representatives of the EU climatic areas: Stockholm, Paris, Milan; Lisbon, Palermo. Definition of building reference cases
Regarding their respective importance in terms of cooling surface, three sectors have been chosen for the study (residence, commercial, office). A flat and a small retail are defined as reference case for the residential and commercial sectors. Regarding the office sector, since it represents most of the air conditioned surface, it is represented by four reference cases whose brief descriptions are given in the table below. The present article concentrates mainly on commercial and office building type. Table 1. Geometrical description of reference case buildings Number Space Glazed areas [% of Envelope surface / of floors disposition the vertical surface] Conditioned volume Office building n°1 12 Open space 45 0,23 Office building n°2 2 Cellular 30 0,57 Office building n°3 5 Cellular 29 0,30 Office building n°4 4 Open space 14 0,47 Small retail 1 Flat 1 Further details about considered base case buildings could be found in [10] (Work Package 4–D.4.1) Building characteristics depend on the climatic area and are supposed to be representative of existing building. Project members coming from the five representative cities (Ecole des Mines de Paris, eERG - Politecnico di Milano, LNEG for Portugal, Swedish Energy Agency) filled in an information request about the existing building stock in their country. A detailed description of the base cases can be found on the KC2 website (www.keep-cool.eu). The conducted dynamic simulations for office buildings considered also that artificial lighting and internal movable solar protections (solar factor of 0,7) are manually controlled by occupants, in function of natural lighting from outside and glare effect. Selection of solutions to be simulated Based on the Keep Cool I project [9], a rather complete list of possible improvements related to summer comfort has been compiled, with a description of the physical principles, the technical implementation and the conditions of applicability. Although it is theoretically possible to apply most of the technologies to any type of building, for practical and economic reasons some of them are mainly suited for new buildings and not existing ones. In addition, particularly we concentrated on actions for whom there is availability of adequate tools to simulate their energy performances. Then, the data required for the simulations have been gathered: technical characteristics, performance level. The final list of EEI actions that are being simulated in order to evaluate savings is given in Table 2. A main issue regarding savings evaluation is interaction between measures. If two actions A and B are both implemented, the combined action AB will not save as much energy as the sum of the two individual actions’ savings. Figure 1 gives examples of interactions that must be faced when dealing with summer comfort (an additional interaction could be added between air conditioning and heating in case of plants based on reversible heat pumps). As a result, EEI actions listed in Table 2 must be studied not only individually but within packages. Figure 1. Example of interactions between actions effects
Table 2. List of EEI actions being analyzed EEI actions to be studied Offices Retails Flats 01. Install an external movable screen blind – Manual Control X X (SF=0,3; Manual control by occupants for visual and glare comfort) 02. Install an external movable screen blind – Radiation control X X (SF=0,3; Radiation control*) 03. Install an external movable venetian blind – Manual Control X X (SF=0,1; Manual control by occupants for visual and glare comfort) 04. Install an external movable venetian blind – Radiation control X X (SF=0,1; Radiation control*) 05. Install an external window awning – Radiation control X (SF=0,3; Radiation control*) 06. Install efficient windows X X X 2 (U=1,09 W/m K; SF=0,315; Visible transmission factor=0,5) 07. Treat wall and roofs with reflective paintings X X (thermal reflectance=0,7) 08. Insulate the roof (thermal insulation) X X 2 (U=0,3 W/m K) 09. Use energy efficient office equipments X (installed electric power=7 W/m2) 10. Install energy efficient lightings and ballasts (installed electric power: X X 10 W/m2 for office rooms; 7 W/m2 for other rooms; 12 W/m2 for retails) 11. Install automatic operable openings - night time (on 50% of the glazed X envelope area, with specific control on in / outdoor temperatures) 12. Install automatic operable openings - day and night time X (equal to action 11, above) 13. Install extraction system for night time ventilation (6 ACH, control like X action 11; fan efficiency=0,7; pressure losses=700 Pa) 14. Install extraction system for day (2 ACH) and night (6 ACH) ventilation X X (control like action 11; fan efficiency=0,7; pressure losses=700 Pa) (where SF means “solar factor”, U “thermal transmittance”, ACH “air changes for hour”, * “Radiation control” consist in a so-called “intelligent control”: blinds are closed if the total solar radiation striking 2 the window exceeds 150 W/m and if the indoor temperature is higher than 22°C). Further technical details about considered EEI actions could be found in [10] (Work Package 4–D.4.2)
Presentation of the methodology for the evaluation of energy savings What does “energy saving” mean in our context? Contrary to other sectors (e.g. lighting, heating, refrigerators), air conditioning penetration in buildings is not close to saturation since a relevant part of the European building stock is not cooled or air conditioned. This particularity must be analyzed: if it is possible to estimate and even measure energy savings in air conditioned (AC) buildings as the difference in consumption after and before the action, how to deal with the others? EEI actions relative to summer comfort in non AC buildings do not reduce the amount of energy currently consumed, but they contribute to reduce or avoid the consumption connected to the possible installation of new active AC systems and in this way, save energy compared to the expected consumption trend in the next years. The situation is therefore the following. EEI actions in AC buildings will reduce the energy need for cooling. In some cases, the energy need for cooling can be reduced sufficiently so that there is no need for active cooling or the energy need can be met with a sustainable passive cooling solution. Naturally ventilated buildings can be comfortable or non comfortable in summer (comfortable buildings can also become uncomfortable during extreme events like heat waves and owners can look for a
cooling solution). Theoretically, we are only interested in uncomfortable ones and face two possible situations: 4. some EEI actions will improve the comfort (reduce the number of overheating hours); 5. some EEI actions (rather packages of actions) will make the building comfortable and hence eliminate the need for air conditioning. In situation “a”, we suggest using the same saving value as that for AC buildings, whereas in situation “b”, the total consumption of the reference building (AC mode) can be taken as obtained saving. General approach The proposed methodology for calculations is represented in Figure 2 and explained hereafter. We propose to study buildings (reference ones or improved ones) in two ways: air conditioned and naturally ventilated (with the possibility to open the windows). Regarding AC buildings, we define comfort conditions to be reached (based on existing standards, mainly EN 15251 [3]) in the base case (BC) and in the base case + EII action (BC+EEI). Then, we suggest calculating the “energy need” to reach this comfort objective for the base case and for the case when a given EEI action has been implemented. From energy needs it becomes possible to calculate the final and primary energy consumptions for the base case and for the case when a certain EEI action has been taken (assuming default efficiency values for distribution systems and generation plants). Regarding naturally ventilated buildings, the simulations enable to derive comfort indices. Then, a comfort criterion (indoor conditions that are considered as comfortable in free ventilated buildings) must be taken into account to conclude if the EEI action (or package) implies a reduction of the cooling load or enables to avoid the use of air conditioning. Main equations
Calculation of unitary gross annual savings in energy needs for cooling needs Annual savings in terms of energy needs for cooling (CN) are determined using this equation: - If even applying the EEI action the comfort criterion is not fulfilled and some cooling need remains:
∆ _ CN = CN ref − CN EEI - If applying the EEI actions the comfort criterion is fulfilled and hence CNEEI = 0: ∆ _ CN = CN ref , where • _CN is the annual saving in terms of cooling needs [kWh/m²|y], CNref is the annual cooling needs of the reference case obtained from simulations [kWh/m²|y], CNEEI is the annual cooling needs of the reference case in which the EEI action has been applied, obtained from simulations [kWh/m²|y].
Calculation of unitary gross annual savings in energy needs for heating Annual savings in terms of energy needs for heating are determined using the following equation:
∆ _ HN = HN ref − HN EEI
, where • _HN is the annual saving in terms of heating needs [kWh/m²|y], HNref is the annual heating needs of the reference case obtained from simulations [kWh/m²|y], HNEEI is the annual heating needs of the reference case in which the EEI action has been applied obtained from simulations [kWh/m²|y].
Calculation of unitary gross annual savings in terms of final energy (delivered energy) A distinction should be made between electricity savings and fuel savings. Annual electricity saving is the sum of electricity savings due to heating and due to cooling:
∆ _ EC =
∆ _ CN SEER ,
∆ _ E H =WEUE ∗
∆ _ HN η EUE
. As previously explained, interactions between energy end-uses must sometimes be taken into account (e.g. the increase of artificial lighting due to solar protection of efficient windows) and added or subtracted to electricity savings due to heating and cooling. Annual fuel savings are assumed to be the result of heating needs reduction:
∆ _ F =W FUE ∗
∆ _ HN η FUE
, where • _EC is the annual savings in terms of electricity stemming from cooling demand reduction [kWh/m²|y], • _EH is the annual savings in terms of electricity stemming from heating demand reduction [kWh/m²|y], • _CN is the annual saving in terms of cooling needs [kWh/m²|y], SEER is the Seasonal Energy Efficiency Ratio in cooling mode representative of the AC existing stock, • _HN is the annual saving in terms of heating needs [kWh/m²|y], • _F is the annual savings in terms of fuel [kWh/m²|y], • FUE is the Seasonal efficiency in heating mode representative of the stock of fuel using equipments, • EUE is the Seasonal efficiency in heating mode representative of the stock of electricity using equipments (heat pump, resistive, etc.), WEUE and WFUE are the repartition factors between electricity using equipments and fuel using equipments (WEUE+WFUE=1).
Comfort assessment When dealing with thermal comfort, a distinction must be made between two terms: - A comfort index is an information on the indoor comfort (e.g. hourly operative temperature, hourly predicted mean vote - PMV) based on measured physical variables and some hypothesis about their interpretation, - A comfort criterion is a factor that allows making a judgment on indoor thermal comfort at a given time (often on an hourly basis) or over a given period. For example the fact to say that “when the temperature is higher than 26 °C the situation is uncomfortable” is a short term criterion whereas “when the temperature is higher than 26 °C more than 10 % of the occupation time, the building is uncomfortable” is a long term criterion. In the developed methodology, in order to conclude if an EEI action could enable to avoid the installation of conventional air conditioning systems we must study the indoor climatic conditions and provide comfort indices. To do this, we applied two thermal comfort models: the PMV/PPD ones and the Adaptive ones. The first was developed mainly by Fanger and it is based on Predicted Mean Vote (PMV) index, which predicts analytically the mean value of the votes of a large group of persons on a 7-point thermal sensation scale. PMV depends on six parameters about considered thermal environment and occupant people (air temperature, mean radiant temperature, air velocity, relative humidity, physical activity and clothing thermal resistance), which influence the heat balance of the human body. To a PMV value corresponds a Predicted Percentage of Dissatisfied (PPD) index value, which represents the expected number of thermally dissatisfied people in a group. Establishing a value to be reached for PMV (and PPD) index and fixing values for other parameters, a comfort operative temperature values and ranges can be calculated. During Summer, in conditions where people can adopt some forms of individual adaptation (e.g. opening and closing of windows, use of fans, dressing changes, etc.) in order to improve their thermal sensation, according to the Standards, higher indoor temperatures can be accepted, because of benefits of adaptations and shifts in occupants expectations. So in spaces where thermal conditions are controlled mainly by opening or closing windows, the Adaptive comfort model can be applied. It was developed by field surveys of Humphreys, Nicol, DeDear and other researchers: according to this model, comfort temperature ranges depends on an adequate mean value of outdoor temperature (running daily mean temperature over the last weeks). Then we applied long term comfort indices defined by the new European Standard EN 15251 [3] defining thermal comfort conditions and consist in the percentage outside range and degree hours criterion based on adaptive comfort range (Category I and II), fixed operative temperatures (default values of the standard), PMV (category I and II) with flexibility on clothing. In particular the “percentage outside the range” method requires to calculate the number or percentage of occupied hours (those during which the building is occupied) when the PMV or the operative temperature is outside a specified range.
In the “degree hours criteria” : the time during which the actual operative temperature exceeds the specified range during the occupied hours is weighted by a factor which is a function of by how many degrees the range has been exceeded. The weighting factor wf equals 0 for • o,limit, lower < • o < • o,limit,upper where • o,limit is the lower or upper limit of the comfort range specified (e.g. 23,0°C < • o < 26,0°C corresponding to –0,5 < PMV < 0,5 as specified in Annex A [3] for single offices, category II, summer). The weighing factor wf is calculated as wf = • o - • o,limit,when • o < • o,limit,lower or • o,limit,upper < • o. For a characteristic period during a year, the product of the weighting factor and time is summed. The summation of the product has the unit of hours: for warm period: • wf· time for • o > • o,limit,upper, for cold period: • wf· time for • o < • o,limit,lower. Other indexes will also be evaluated [8]. Then it is up to the user to choose the comfort criterion and the conditions from which the building is assumed to not require AC. The default criterion used to derive default values is that a building is assumed to be comfortable if the percentage of time outside zone is lower than 5 % over the summer. The default zone is the adaptive comfort one defined in EN 15251, category II [3]. User behaviour is taken into account by developing algorithms which simulate: 1. the use of movable shadings by occupants in order to control visual discomfort, 2. the use of artificial lighting by occupants in response to different levels of daylighting, 3. the use of operable windows in summer in response to temperature levels. Figure 2. General methodology
Main results We present some of main results in term of energy needs for cooling, for buildings in air conditioned (AC) mode, and thermal comfort according to Adaptive and Fanger models (see above), for natural ventilated (“vented”) buildings, for office building n°1, 2, 3, 4, and small retail. We consider single EEI actions and some adequate packages (Pack.) of actions described below (see also Table 2): For office buildings - Pack. 1: energy efficient office equipments + energy efficient lighting (actions 09.+10.)
- Pack. 2: Pack. 1 + external venetian blind with radiation control (actions 09.+10.+04.) - Pack. 3: Pack. 2 + automatic operable openings at day and night time (actions 09.+10.+04.+12.) - Pack. 4: Pack. 3 + efficient windows + insulate the roof(actions 09.+10.+04.+12.+06+08.); For small retail - Pack. 5: external window awning with radiation control + energy efficient lighting (actions 05.+10.) - Pack. 6: all the actions considered for small retail (actions 05.+06.+10.+14.). Figure 3. Office building n°1: (3a) energy need for cooling (AC mode) and (3b) thermal comfort conditions (naturally ventilated mode) for the various EEI actions studied independently
[%| y] .e xte rna l sc
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r ef ere ree nc xte nb ec rna li n as d( l sc e M r an ee 03 ua nb .e lC xte li nd on rna (R tro l a v l) 04 d e i n a ti .e e tia on xte nb Co rna lind n tr l ve ol ) (M ne an tia ua nb lC l ind on 07 (R a tro . tr l) d ea iati tw o n a ll 06 Co an .e ntr dr ffic ol) oo i en fs tw wi t ind hr ow efl s ec tive p a 09 int .e ing 08 ne . in s rg y su lat eff et i ci he en to ro o ffi c f 11 e 1 e .a 0. qu uto en ipm ma erg en 12 tic ye ts .a op ffi c uto e i rab ma en t lig tic le op hti op en ng era 13 ing ble .e s xtr op (ni ac gh en ti o 14 t ti ing ns .e me s xtr y ( ) da ste ac y+ m ti o n ig for ns ht yst ni g tim em ht e) t i for me da ve y+ ntil n ig ati ht on ti m ev en tila tio n
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Figure 4. Office building n°2: (4a) energy need for cooling (AC mode) and (4b) thermal comfort conditions (naturally ventilated mode) for the various EEI actions studied independently
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Figure 5. Office building n°1: (5a) energy need for cooling (AC mode) and (5b) thermal comfort conditions (naturally ventilated mode) for the applied packages of EEI actions
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Figure 6. Office building n°2: (6a) energy need for cooling (AC mode) and (6b) thermal comfort conditions (naturally ventilated mode) for the applied packages of EEI actions 120
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Figure 7. Office building n°3 (7a) and Office building n°4 (7b): energy need for cooling (AC mode) for the various EEI actions and packages applied
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Discussion
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By using the developed methodology, we show typical values of energy savings related to single or packaged technical measures of sustainable summer comfort applied to typical building types and systems, in typical european climate conditions. The adoption of different types of shadowing devices and relative manual and automatic controls and the use of adequate ventilation strategies show great potential in energy savings for cooling, reaching a reduction of energy needs for cooling up to almost 50% respect to reference base cases by applying single EEI actions. In some cases, the adoption of packages of actions can avoid the need of a traditional cooling system. Energy saving potential of solar protection devices (screen blind, venetian blind) naturally increases with reduction of their solar factor values. The adoption of automatic radiation control (see Table 2) of shadowing movable devices allows to optimize the use of solar protection components and to reach greater reduction of energy needs for cooling. Adequate ventilation strategies have great potential for cooling energy savings, particularly by adopting automatic control in function of indoor and outdoor temperatures. Natural and mechanical ventilation during day and night time allows to dissipate thermal gains and loads, when it’s necessary and possible. It also could be interesting to consider that various EEI actions (e.g. solar protection, ventilation, thermal insulation, etc.) could be adopted in one component like particular window or façade component type, relatively easy to install in buildings refurbishments.
Acknowledgement Other materials and further results can be found at www.keep-cool.eu and www.keep-cool.net. Funding was provided by the IEE programme.
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Pagliano L. and Zangheri P. 2005. Climate optimized building parameters for low energy summer comfort under a discomfort index. ; 19-21 May 2005; Palenc 2005, Santorini, Greece, p. 231-237.
[9]
Varga M. and Pagliano L. 2006. Reducing cooling energy demand in service buildings. ; 26 - 27 April 2006; Frankfurt, Germany, IEECB 2006, p. 257-266.
[10]
European
Commission
supported
project
keepCool2
web-site:
www.keep-cool.eu
HARMONAC: Quantifying the Energy Conservation Opportunities in Air-Conditioning Inspections as required by EPBD Article 9 Ian Knight and James Cambray Welsh School of Architecture, Cardiff University, Cardiff, UK
Abstract HARMONAC [1] is an Intelligent Energy Europe (IEE) project aimed at maximising the cost: energy savings ratio across Europe from undertaking AC System Inspections as required by the Energy Performance of Buildings Directive (EPBD) [2]. HARMONAC builds upon the IEE AUDITAC project [3] which highlighted the major lack of data concerning the energy consumption of AC systems in practice. By coupling long-term measurements of the energy consumption of AC systems in EU Member States with short term Field Trials of AC System Inspections, the HARMONAC project is producing unique and detailed information which will help quantify the practical usefulness, in energy saving terms, of each of the elements of an AC System Inspection when applied across Europe. It is expected that the HARMONAC project outputs will be used to improve the AC Inspection process in many EU Member States, thereby helping to make Inspections both cost-effective and useful in achieving real world energy efficiency improvements. The final HARMONAC project report is due in autumn 2010. This paper presents an overview and examples of the energy savings found in practice from the Case Studies and Field Trials undertaken for the project to the date of writing the paper. It highlights which are the most frequently occurring Energy Conservation Opportunities (ECO) during Field Trials of the HARMONAC AC Inspection Methodology, the calculated savings for each ECO identified, and information on how they were calculated. The project to date has identified that the detailed inspection of AC systems is capable of identifying significant energy saving opportunities, with savings of 25 – 50% being regularly identified in the project Case Study sample systems. However, the Field Trials sample systems show that it is likely that many of the potentially larger savings will not be identified by the current AC Inspection requirements, as many of the savings being found in the Case Studies are control based and the information needed to identify these is not generally available from short-term inspections. Finally the project is also showing that Inspection may be able to identify potential ECOs for a given system, but is unlikely to have the data needed to quantify any potential saving. This makes it harder to engage the system owner/operator in actions to improve energy consumption in practice.
Nomenclature IEE - Intelligent Energy Europe. A European Commission supported project. HARMONAC - Harmonizing Air Conditioning Inspection and Audit Procedures in the Tertiary Building Sector EPBD - Directive 2002/91/EC of the European Parliament and of the Council on the Energy Performance of Buildings AUDITAC - Field Benchmarking and Market Development for Audit Methods in Air Conditioning EN15240 - Ventilation for buildings - Energy performance of buildings - Guidelines for inspection of air-conditioning systems CIBSE TM4 - Inspection of Air Conditioning Systems Methodology ECO - Energy Conservation Opportunity BMS - Building Management System
Introduction The main aims of the IEE HARMONAC Project are: •
• •
•
to test HARMONAC versions of the CEN 15240 [4] and CIBSE TM44 [5] AC System Inspection procedures to see how long each inspection item takes to complete in practice, and which inspection items identify which energy conservation opportunities (ECOs) in practice to quantify through long-term measurement and Field Trials the size and frequency of energy savings potentially available from Inspection, to produce a range of HARMONAC AC system inspection procedures as a result of the project that would address what the HARMONAC Partners consider to be a minimum set of inspection items; an optimum set (balance of time:savings) of inspection items; and a full set of inspection items. to produce tools and teaching packages to assist in the inspection process
The rest of this paper deals primarily with the range of ECOs identified in HARMONAC; the size of savings being found for those ECOs quantified to date; and the frequency of occurrence of those ECOs when the HARMONAC AC Inspection Procedures are undertaken in Field Trial studies.
AC System Energy Conservation Opportunities (ECOs) The HARMONAC project has to date identified 137 separate ECOs for AC systems. It is in the process of obtaining estimates of energy saving potential for as many of these as possible before the end of the project. The ECOs are divided into 3 categories associated with Envelope, Plant and Operational aspects of AC system operation. Table 12 shows how these 3 categories subdivide into 14 further subcategories comprising 4 Envelope (E) related subcategories containing 33 ECOs; 6 Plant (P) related subcategories containing 47 ECOs; and 4 Operational (O) subcategories containing 57 ECOs. Table 12 - Energy Conservation Opportunity Main- and Sub- Categories used in HARMONAC Code E1.# E2.# E3.# E4.# P1.# P2.# P3.# P4.# P5.# P6.# O1.# O2.# O3.# O4.#
Number of ECOs in code 7 8 9 9 7 14 14 5 5 2 7 8 20 22
ECO Solar gain reduction / Daylight control improvement Ventilation / Air movement / Air leakage improvement Envelope insulation Other actions aimed at load reduction BEMS and controls / Miscellaneous Cooling equipment / Free cooling Air handling / Heat recovery / Air distribution Water handling / Water distribution Terminal units System replacement (in specific limited zones) Facility management General HVAC system Cooling equipment Fluid (air and water) handling and distribution
The full list of ECOs can be found in the HARMONAC website [1], and the savings associated with each ECO will be updated throughout the remaining period as the findings come in from the Case Studies and Field Trials. The following bullet points represent the main findings and range of savings found for each Category of ECO to the date of this paper:
• • •
Envelope ECOs (including equipment). Lighting daylight linking can provide savings up to 20% of building energy use. Usual saving ranges appear to be 2 – 9 kWh/m2/pa electricity Plant ECOs. Most common saving range appears to be 1 – 8 kWh/m2/pa electricity. Savings of up to 9% of building electricity use have been found. Operational ECOs. Most common saving range appears to be 1 – 20 kWh/m2/pa electricity. Savings of up to 19% of building electricity use have been found.
In addition to the above points significant benefits have been found for gas use as well from some ECOs. The most common ECOs are to be found amongst the Operational ECOs. The final observation is that virtually all the CS and FT assessed to date have had opportunities to reduce the output from, or turn off all or some part of, the HVAC system for some part of each day.
Quantifying and Evaluating AC System ECOs from Case Studies There are now numerous examples of ECOs and their derivation within the HARMONAC project. The nature of any funded project means that there is limited time to explore all the issues arising, and in the case of AC systems the time and cost needed to implement some potential ECOs is prohibitive. Where this is the case, and where we cannot directly measure savings, then the more frequently occurring ECOs are being estimated through modelling using bespoke software [1] produced by the HARMONAC Partners. Whether the savings due to an ECO are obtained from measurement, prior research, modelling or other means, the derivation of the savings attributed to each Case Study and Field Trial ECO is being clearly recorded, so that a user of the HARMONAC data can decide how confident they are in the likely range of savings to be achieved by an ECO for their specific situation. Two examples of ECOs obtained from HARMONAC UK Case Study 10 are presented next. They have been chosen due to the clarity of the information used to identify them, the accuracy with which they can be evaluated, the fact that identification of one saving led to the next being identified, and the manner in which they illustrate the importance of good data collection to being able to save energy in practice through providing unambiguous information to the AC system owner. Example 1. ECO O2.3: Shut off auxiliaries when not required and ECO O4.19: Switch off circulation pumps when not required The ECO identified by this case study is a Commissioning problem. It shows how metered electricity data was used to reveal a problem with the operation of the CHW pump in the building. There are 2 ECOs associated with this measure as the CHW pumps could be separated from other auxiliary energy use in this Case Study. The building was occupied in May 2008 and energy data being retrieved from the building services and the building as a whole is shown for July 2009 in Figure 29. This data shows that the HVAC system accounted for a little over 27% of the
Figure 29 – Metered electricity use in UK Case Study building Total - kWh for July 2009
Chillers
62,841
Chilled Water Pumps 4,514 22,762
Main AHU's Roof Plant
32,264
214,326
Tenant Offices Power Tenant Offices Lighting
34,532
66,680
Other inc lifts, UPS, Comms Rooms, Kitchens
Figure 30 – AC system components electrical consumption profiles over 2 months June to July 2009 - Main AC System electricity consumption profile 80 70
kWh every 15 mins
60 50 40 30
Chiller Fans CHW Pumps
20 10
01/01/1900 06/04/1900 11/07/1900 15/10/1900 19/01/1901 25/04/1901 30/07/1901 03/11/1901 07/02/1902 14/05/1902 18/08/1902 22/11/1902 26/02/1903 02/06/1903 06/09/1903 11/12/1903 16/03/1904 20/06/1904 24/09/1904 29/12/1904 04/04/1905 09/07/1905 13/10/1905 17/01/1906 23/04/1906 28/07/1906 01/11/1906 05/02/1907 12/05/1907 16/08/1907 20/11/1907 24/02/1908 30/05/1908 03/09/1908 08/12/1908 14/03/1909 18/06/1909 22/09/1909 27/12/1909 02/04/1910 07/07/1910 11/10/1910 15/01/1911 21/04/1911 26/07/1911 30/10/1911 03/02/1912 09/05/1912 13/08/1912 17/11/1912 21/02/1913 28/05/1913 01/09/1913 06/12/1913 12/03/1914 16/06/1914 20/09/1914 25/12/1914 31/03/1915
0
total energy use of the building in this month. The graph in Figure 30 shows the AC system components (Chillers, Fans and Chilled Water Pump) energy signatures in June and July 2009. These signatures reveal that the AHU’s and Chillers in the building run continuously, and that there is an odd spike in consumption of the pumps and chillers at the end of each day around Figure 31 – Carpet plot of CHW pump use in 15 minute intervals 23:15 to 00:15. Figure 31 shows this data using the carpet plot technique. This technique finds the highest consumption value in one time interval over the time period being investigated and then divides the consumptions per time interval into 10% bands which are coloured from dark blue representing 0 – 10% of the peak demand through to white representing 90 – 100% of the peak demand. So each column represents a day, and each coloured box one time interval. Here 15 minute data is shown. The figure clearly shows this high CHW pump consumption occurring between 23:15 and 00:15 nearly every day. This consumption was not visible at all to the building owner/operator as no-one was in the building at this time to note the pumps running, but the impact of these CHW pumps running flat out at this time was that the Chillers were also being called into action as well as they are continually energized Figure 32 – Carpet plot of CHW pump use after control change awaiting the cooling water flow. Following investigation by the building owner/ operators it was found that this fault was a commissioning issue that had not been noticed on building handover. The
pump had an exercise routine built in for an hour at this time every day to ensure that it did not seize while the building was unoccupied and the services were completed and commissioned. Using the data collected from the metering we were able to calculate that removing this pump exercise control regime would reduce the total AC system energy consumption by 4%, comprised of a 12.1% reduction in the CHW pump energy use and a 5.2% reduction in the Chillers consumption. The building owner/ operators were able to quickly implement this change and the new carpet plot showing this change implemented is shown in Figure 32. This figure also shows that the CHW pump energy use has reduced significantly in other parts of the day as well. These additional savings are thought to be due to reduced cooling demand due to weather conditions and fewer occupants during August, but it helps to show that the CHW pumps are reacting well to this reduced demand i.e. that the control now seems reasonable ASSUMING THAT 24 HOUR COOLING IS REQUIRED. This brings us onto the next ECO to be shown in this paper. The AHU fans were unaffected by this change as they are controlled independently of the CHW pump. However, the building occupancy is NOT 24 hour – the only out of hours use is for cleaning and the services are rarely needed for this activity in most weather conditions. The next study therefore looked at why the AC system and ventilation system were running 24 hours per day. Example 2. ECO P1.7: Reduce power consumption of auxiliary equipment; ECO O2.3: Shut off auxiliaries when not required; ECO O4.9: Reduce Figure 34 – Carpet plot of AHU North energy use in June air flow rate to actual needs. 2009 The detailed component level electrical consumption metering revealed that the Air Handling Units in the building were providing the same airchange rate in the building 24 hours per day, 7 days a week when the building was only occupied from 07:00 to 21:00 most weekdays, and even less on weekends. In discussion with the building owner/operators they decided this was not necessary and changed the BMS settings to turn off the AHUs to the occupied zones to reflect these periods. This occurred at about the same time as the CHW pump change was made i.e on 15th August 2009. Figure 34 shows the AHU energy consumption profile occurring in June 2009. It was assumed that this change had been implemented until further analysis of the data was undertaken by the authors in November 2009. At this point it was noted that the AHU was still running 24 hours a
Figure 33 – Carpet plot of AHU North in December 2009
day. Discussions with the building owner/operators led to the discovery that, even though the BMS had been set to control the AHU correctly, at some point someone had switched the control of the AHU from automatic to manual, probably during a service operation, and had failed to reset the control back to the BMS on completion. Figure 33 shows the savings that occurred in December when this fault was found and rectified. The full extent of the savings has yet to be analysed but the AHU alone reduced its consumption by 45%. There will clearly also be knock-on effects on the AC Chillers and the building boilers consumptions and the analysis will attempt to assess these savings as well before the end of the Case Study. Further potential savings are expected to be made in the operation and control of the Chillers themselves – with questions being asked about why all 3 substantial Chillers need to be energized all year round when the measured loads show they are all operating at only 10 – 30% of their peak consumption (not even peak capacity) for most of the year, and for 24 hours a day. It is hoped discussions with the manufacturer might reveal whether the AC units could be fully turned off for part of the year provided appropriate reactivation procedures are followed when the cooling demand reappears.
AC System ECOs identified from Field Trials The last part of this paper considers the ECOs found from over 120 Field Trials of the HARMONAC AC Inspection Procedures undertaken in conjunction with a regular Maintenance visit [6]. It can be seen from Table 13 that only a very few ECOs were capable of being identified and quantified by this combined Inspection/Maintenance approach. At present this table refers almost exclusively to small scale Packaged Split systems. Table 13 - Range of quantified savings by Inspection item for Packaged Systems Average PRE-INSPECTION % Savings PP1 List of installed refrigeration plant 0 PP2 Method of control of temperature. 0 PP3 Method of control of periods of operation 0 PP4 Reports from earlier AC inspections and EPC’s 0 PP5 Records of maintenance operations 0 PP6 Records of maintenance (control systems and sensors) 0 PP7 Records of sub-metered air conditioning plant (use or energy) 0 PP8 Design cooling load for each system 0 PP9 Description of the occupation of the cooled spaces 0 INSPECTION P1 Review available documentation from pre-inspection 0 P2 Locate the plant and compare details with pre-inspection data 0 P3 Locate supply to the A/C system and install VA logger(s) 0 P4 Review current inspection and maintenance regime 17 (Filter cleaning) P5 Compare size with imposed cooling loads * P6 Compare records of use or sub-metered energy with expectations 0 P7 Locate outdoor plant 0 P8 Check for signs of refrigerant leakage. 36.1 P9 Check plant is capable of providing cooling 0 P10 Check external heat exchangers 3.9 P11 Check location of outdoor unit 0 P12 Assess zoning in relation to internal gain and orientation 0 P13 Check indicated weekday and time on controllers against actual 0 P14 Note the set on and off periods 0 P15 Identify zone heating and cooling temperature control sensors. 0 P16 Note set temperatures in relation to the activities and occupancy *
P17 Provision of controls or guidance on use while windows open P18 Type, age and method of capacity control of the equipment P19 Write report *savings still to be determined
0 0
Table 14 [6] shows how often an ECO was identified as a percentage of the Field Trials undertaken to date, and whether Maintenance was required to identify it or whether Pre or Site Inspection would suffice. The savings identified in Table 13 are now seen associated with their specific ECO as well. From Table 14 we can see that nearly all of the main ECOs being found from the Case Studies are not possible to quantify during an Inspection. They can be identified by Inspection but will rely on data on average savings from other sources, such as HARMONAC, to provide guidance to the system owner and the magnitude of savings that might be achieved. This inability of an Inspection to quantify the size of potential savings applicable to a specific AC system, when long-term data relating specifically to the AC system energy use in not available, is likely to be a major hurdle to actually achieving some of the major energy savings available, as owners appear generally reluctant to invest time and money in uncertain opportunities. It can be clearly seen that after ‘dirty filters’ the ECOs most frequently occurring are those related to control issues, and in all these cases a potential saving was unable to be assessed from the Field Trial or Maintenance procedures. Table 14 – ECOs identified through the Field Trials Potential ECO
Occurrence %
No manufacturer’s user instructions on site Dirty Filters Non sequencing of multiple units Set point too low () Equipment needs replacing Lack of air flow through wrong fan rotation etc. Short of refrigerant Air leakage on ductwork Consider smaller system Consider reducing room size area
77 51 47 46 42 36 34 19 19 17 9 9 9 7 7 7 5 4 4 3 3 3 2 2
Savings calculated %
Maintenance needed to identify?
17
Yes Pre Pre Pre Site Pre Pre
2 to 4% per 1K * * Not yet calculated
Yes Yes
* Not yet calculated Not yet calculated 17
Yes
* Not yet calculated
Yes Yes
36
Yes
Not yet calculated
Type of Inspection needed to identify? Pre
Pre Site Site Site Site Site Pre Site Pre Site Site Site Pre Pre / Site
Return air filter missing Modify vegetation Grilles blanked off * No long term data available to calculate.
2 2 1
Up to 50%
Yes Site Site
Conclusions The main conclusions from the project to date are: 1. That there are worthwhile and frequently occurring ECOs to be found from attending to the operation, control and maintenance of Air Conditioning systems. 2. That current AC Inspection procedures will be able to identify some of these ECOs during an Inspection, but will be unable to quantify a saving for specific systems for many of the ECOs. 3. Undertaking Maintenance with an Inspection can quantify and identify more ECOs than Inspection alone 4. Full understanding of the operation of an AC system, and therefore of the ECOs related to it, can only be achieved through long-term data collection and analysis relating to the energy use of the system and desired conditions in the building at sub-hourly intervals. This means undertaking temperature and energy data collection on a regular and automatic basis. The HARMONAC project is moving into its final data collection and analysis phase now. Case Study data collection will finish around July 2010 and the final report will be available by the end of October 2010.
Acknowledgements The authors wish to acknowledge the input of the HARMONAC partners in the data which has been used in this paper. HARMONAC is funded by the European Commission through the Intelligent Energy Europe programme.
The sole responsibility for the content of this paper lies with the authors. It does not necessarily reflect the opinion of the European Communities. The European Commission is not responsible for any use that may be made of the information contained therein.
References [1] Harmonizing Air Conditioning Inspection and Audit Procedures in the Tertiary Building Sector (HARMONAC). IEE Project EIE/07/132/SI2.466705. September 2007 – August 2010. Website: www.harmonac.info [2] Directive 2002/91/EC of the European Parliament and of the Council on the Energy Performance of Buildings. 16 December 2002, Brussels [3] Field Benchmarking and Market Development for Audit Methods in Air Conditioning (AUDITAC). IEE Project EIE/04/104/S07.38632. January 2005 to December 2006. Website: http://www.eva.ac.at/projekte/auditac.htm [4] CEN Standard EN15240 - Ventilation for buildings - Energy performance of buildings Guidelines for inspection of air-conditioning systems. www.cen.eu [5] CIBSE TM44: Inspection of Air Conditioning Systems. CIBSE, 2007 ISBN: 9781903287859 http://www.cibse.org/index.cfm?go=publications.view&item=372
[6] Dave Wright, Ian Knight and Mark Sheldon - Lessons learnt from undertaking hundreds of EPBD Article 9 Inspections of Air conditioning systems - findings and observations from the HARMONAC Project industrial partner. Forthcoming paper in CLIMA 2010 Conference, Istanbul, Turkey, May 2010
Maximizing Refrigeration Efficiency in New Commercial Buildings Ken Tiedemann and Iris Sulyma BC Hydro, Vancouver, Canada
Abstract The High Performance Building (HPB) program was formally launched by BC Hydro in July 2005, but several pilot refrigeration projects were folded into the program. The objective of the HPB program is to accelerate the demand and production of new commercial and industrial high performance/energy efficient buildings and industrial plants. The rationale for the program is to effectively address barriers limiting the design and construction of new energy-efficient commercial and industrial buildings and facilities in British Columbia. The program provides: (1) tools and financial incentives to address financial barriers; (2) education and training to address industry capacity constraint barriers; (3) promotional campaigns to address owner, developer and occupants awareness and understanding of energy efficiency barriers; and (4) recognition programs to address strategic knowledge of energy issues barriers. This paper presents the results of a process and impact evaluation of five refrigeration projects conducted as the pilot phase of the High Performance Building Program.
Introduction The High Performance Building (HPB) program was formally launched by BC Hydro in July 2005, but several pilot refrigeration projects were folded into the program. The objective of the HPB program is to accelerate the demand and production of new commercial and industrial high performance/energy efficient buildings and industrial plants. The rationale for the program is to effectively address barriers limiting the design and construction of new energy-efficient commercial and industrial buildings and facilities in British Columbia. The program provides: (1) tools and financial incentives to address financial barriers; (2) education and training to address industry capacity constraint barriers; (3) promotional campaigns to address owner, developer and occupants awareness and understanding of energy efficiency barriers; and (4) recognition programs to address strategic knowledge of energy issues barriers. The HPB program targets those who are influential in the decision-making process of new construction projects. The program also aims to educate building occupants of the benefits of living and working in a high-performance building. In time, prospective purchasers and lessees will choose to purchase or lease high-performance buildings over buildings of conventional design. The program is for large new projects that are at least 50,000 square feet in area or are electricity-intensive facilities, such as arenas, refrigerated warehouses or grocery stores. Minimum savings criteria apply, and projects are considered as qualified once certain guidelines have been met. The primary audience for the program includes: Building Owners; Building Developers; and Design Teams of new construction projects including architects, consultants and engineers. BC Hydro will assist the customer through two phases of the High-Performance Building Program: (1) BC Hydro will co-fund an energy study to develop a high-performance design that delivers energy savings, compared with conventional building design; (2) BC Hydro may provide incentives to help qualified projects implement the approved design. This study focuses on five refrigeration projects which were undertaken during the pilot phase of the program. Refrigeration systems account for about ten percent of commercial electricity use in North America. (Nadel [1]). The major categories of commercial refrigeration systems are packaged refrigeration systems and built up refrigeration systems. The packaged systems include the components of the refrigeration system in a single package. The built up refrigeration systems are custom designed and built on site. Packaged systems comprise about two-thirds of commercial refrigeration energy use (Arthur D. Little [2], Easton Consultants [3], NYSERDA [4]). This purpose of this paper is to provide a process and impact evaluation of the commercial refrigeration component of the High Performance Building Program.
Data and Method Evaluations of DSM programs which focus on new commercial construction are complicated by the fact that there is no pre-retrofit situation to serve as a basis for comparison with the post-retrofit situation. Evaluation in this situation has to depend upon some combination of metered data, engineering algorithms, and engineering simulations. This study examines five cases studies where energy efficient refrigeration and freezing systems were the key technologies installed. The approach for this study follows the International Performance Measurement & Verification Protocols (IPMVP, see DOE [5]). The four IPMVP options, which are summarized in Table 1, are: (1) Option A. Partially Measured Retrofit Isolation; (2) Option B. Retrofit Isolation; (3) Option C. Whole Facility; and (4) Option D. Calibrated Simulation. Table 1. Summary of IPMVP Options Measurement and verification option
Savings calculations
Typical applications
Option A. Savings are determined by partial field measurement of energy use system(s) to which a measure was applied, separate from facility energy use. Measurements may be either short term or continuous. Partial measurement means that some but not all parameters may be stipulated.
Engineering calculations using short term or continuous post-retrofit measurements or stipulations.
Pre- and post-retrofit values are measured with a kW meter and operating hours are based on interviews with occupants or stipulated values.
Option B. Savings are determined by field measurement of energy use of the systems to which the measure was applied; separate from the energy use of the rest of the facility. Short term or continuous measurements are taken throughout the post-retrofit period.
Engineering calculations using short term or continuous measurements.
Electricity use is measured with kW meter. Hours of operation are measured with motor loggers.
Option C. Savings are determined through simulation of energy use of components or the whole facility. Short term or continuous measurements are taken throughout the postretrofit period.
Analysis of whole facility utility or submeter data using simple comparisons, regression analysis, or conditional demand analysis.
Utility meters measure energy use for 12month base year and throughout the retrofit period.
Option D. Savings are determined by partial field measurement of energy use system(s) to which measurement was applied, separate from facility energy use. Simulation routines must be demonstrated to adequately model actual energy performance measured in that facility.
Energy use simulation, calibrated with hourly or monthly utility billing data and/or end use metering
Utility billing meters measure pre- or postretrofit energy use. Savings are determined by calibrated simulations.
Refrigeration System Basics Refrigerator system basics are discussed in a large number of sources including, as examples, Resource Smart [4], Carbon Trust [5], Government of Australia [6], Industrial Efficiency Alliance [7], and Reindl [8]. A number of refrigeration cycles are used in commercial and industrial applications, but the most common is probably the vapor compression cycle. The basic components of the mechanical compression system include an evaporator, compressor, condenser and expansion valve.
The heat transfer liquid or refrigerant changes state from gas to liquid and back to gas continuously throughout the vapor compression cycle. The vapor compression cycle can be summarized in four stages as follows. “Stage 1: The refrigerant is in a cold gaseous state, having just changed state from a liquid to a gas after absorbing heat in the evaporator for the process (or air). A refrigerant in liquid form will absorb significant amounts of heat during evaporation – it is this phase change that enhances the cooling effect in the refrigeration process. Stage 2. The gas is then compressed by the compressor and discharged as a hot gas. The hot gas enters the condenser where it releases its latent heat of evaporation to either water or air. The heat released is equivalent to the heat absorbed by the refrigerant in the evaporator plus the heat created by compression input. In this stage, the refrigerant will become liquid again. Stage 3. The refrigerant leaves the condenser as a hot liquid and then passes through the expansion valve, which expands the hot liquid into a cold liquid. Stage 4. The cold liquid flows into the evaporator where the cycle begins again. The fluid is boiled off (that is, evaporated) to a cold gas by the heat of the product being refrigerated. The cold gas returns to the inlet (or suction) of the compressor (Resource Smart [6], p.26)”. Table 2 provides a summary of potential energy savings by energy savings method. Note that these savings are not necessarily cumulative, since using a given method will reduce energy consumption and may thus reduce the potential for additional energy saving methods. Table 2. Potential Refrigeration System Energy Savings Method
Potential energy savings (unless otherwise noted)
Use of electronic expansion valves
20%
VSD on motors
20%
VSD on evaporator and condenser fans
2-3% of total refrigeration costs
Evaporator pressure regulators
2% for each degree increase in saturated suction temperature
Reduced temperature lift
3-4% reduction for 1degree Celsius reduction
Conversion from liquid injection oil cooling to external oil cooling
Over 3%
Refrigeration system replacement if older than 10 years
Up to 30-40%
Appropriate refrigerant selection Source. Resources Smart [6].
3-10%
Process Results Program Effectiveness. Based on a file review, literature review, program staff interviews and stake holder interviews, a number of major findings emerged. First, incentive levels vary substantially across the new construction programs of various utilities, but many programs provide incentives equivalent to about 40% to 60% of incremental costs, which is about the share of incremental costs covered by BC Hydro for the refrigeration case studies examined. Second, tiered incentives, where the incentive level is based on the level of energy efficiency improvement above the baseline, are successfully used by some utilities. Third, for many U.S. utilities, a whole building baseline is determined through whole building simulations such as DOE 2.1 to establish the expected energy savings over the baseline. Fourth, the current program procedures are not viewed as particularly burdensome per se, but some concerns were raised about the length of time required for BC Hydro turn-around of documentation.
Fifth, some interviewees felt that the effectiveness of program marketing could be improved, since program marketing depends heavily on Lunch and Learn sessions, which do not necessarily reach the key intended audiences including developers, owners and senior officials of architectural and engineering firms. Market Characterization. Several key features of the new commercial construction market in British Columbia stand out. First, the construction industry is primarily cost driven by the underlying economics, with construction costs, operating costs, vacancy rates, revenues and return on investment being the key drivers. Second, construction design typically focuses on visible building features, because they are what sell new commercial and industrial space. Third, increased energy efficiency is a hard sell because triple net leasing means that the agent owning the building does not capture the gains from energy efficiency and because economic pay-back longer than five years is not viewed as attractive. Fourth, energy efficiency is often an after thought, with relatively little attention paid to integrated design in the early stages of building design. Market Potential. New construction in British Columbia goes through fairly regular cycles in response to changes in the level of economic activity, interest rates, vacancy rates, the incremental stock currently under construction and forecasts of future economic conditions. Levels of new construction vary by segment in response to changes in rates of return and risk by segment. The key nonresidential construction segments are expected to be industrial, large and small offices, non-food retail, wholesale and warehouse, educational facilities and hotels and motels over the next three years. Several of these segments have substantial refrigeration loads and offer major opportunities for energy and peak savings. Free Riders and Spill Over. During the process study interviews, standard free rider and spillover questions were asked of program participants. There was no evidence of either free riders or spillover, but since the projects were part of a pilot, this is not surprising, since participants were custom recruited into the program for specific refrigeration facilities.
Engineering Analysis The engineering analysis uses five refrigeration case studies summarized in Table 3. Table 3. Refrigeration Case Studies Project
Project summary
Analysis
Multiplex arena
New ammonia refrigeration plant for 85,000 square foot complex including computer controls, larger evaporative cooler, supplementary 7.5 HP pony pump for low load conditions, VSD on 30 HP condenser fan, new condenser fan
Power loggers installed for 7 months or more on the fans, pumps, and compressors and actual and simulated consumption compared
Refrigerated warehouse
New refrigeration system serving four blast freezers, two freezer storage rooms, one cooler and one loading dock with features including evaporative cooler with lower discharge pressure, multiple condenser fans, waste heat recovery, compressor oil cooling, defrost thicker insulation, VSDs on compressors (capacity increased from 140,000 lb/day to 318,000 lb/day)
Refrigeration system modeling using design refrigeration loads, run hours, and part load operating conditions, calibrated to metered load and actual and modeled consumption compared
Food processor
New refrigeration system using blast freezers and freezer storage room with VSDs installed on compressors as the only energy conservation measure
Power meters were installed on the compressors and actual and modeled consumption compared
Refrigerated warehouse
New refrigerated warehouse including a 92 ton refrigeration system serving food packaging and preparation areas at 30°F and a 137 ton refrigeration system serving a spiral freezer for storing product at 45°F with the following features: reduced condensing
Savings based on measured operating hours on compressors and the condenser combined with onsite inspections to ensure
Food processor
temperature, thermosyphon oil cooling, computer system controls, condenser fan and compressor VSDs
proper system operation
New refrigeration system serving two blast freezers, freezer storage room and cooler and production room with one-100 ton compressor, one-200 ton compressor with VSD, one-250 ton compressor with VSD, added insulation, waste heat recovery, defrost
Power meters were installed for one year on three compressors and actual and modeled consumption compared
Energy and peak demand savings for the case studies were determined using Option B (Retrofit Isolation) and Option D (Calibrated Simulation). Field visits were undertaken to: (1) compare plant drawings to actual plant layout; (2) inspect the installed equipment to ensure that equipment was installed and operating appropriately; and (3) install power meters, power loggers and lighting loggers. Metered data was downloaded, cleaned and stored in a database. Engineering algorithms and simulations were used to estimate energy and demand savings.
Energy and Peak Impacts Table 4 compares the results of the Monitoring and Verification analysis with the programs’ reported savings for the five refrigeration projects. One project had no savings as the modeled consumption without ASDs was essentially the same as the actual consumption with ASDs. For the four other projects, the realization rate varied from 77.1% to 106.5%. The overall realization rate was 80.7%, again it was brought down somewhat by the non-performing project. Table 4. Claimed and Verified Project Savings Project
Claimed savings (GWh)
M&V savings (GWh)
Ratio M&V/claimed (%)
Multiplex arena
0.464
0.494
106.5
Refrigerated warehouse
1.699
1.310
77.1
Food processor
0.303
None
0.0
Refrigerated warehouse
0.775
0.775
100.0
Food processor
1.571
1.306
83.1
Total
4.812
3.885
80.7
Table 5 summarizes key impact savings results and compares these to the initial reported estimates made by the program management. Energy savings were initially estimated at 4.8 GWh per year and peak savings were initially estimated at 1.07 MW. Evaluated energy savings were 3.9 GWh and evaluated peak savings were 0.7 MW. Table 5. Reported and Evaluated Energy and Peak Savings Period Net savings
F2004-06
Energy Savings (GWh)
Peak Savings (MW)
Reported
Evaluated
Reported
Evaluated
4.8
3.9
1.0
0.7
Cost Effectiveness Table 6 shows the estimated cost effectiveness for the five refrigeration projects. The pay back period is defined as incremental costs divided by the value of incremental energy savings. One project had no payback as the estimated savings were zero. The pay back periods for the four other projects range from 3.6 years to 4.8 years. Previous research suggests that a payback period of five years or less is generally acceptable in the commercial sector in British Columbia.
Table 6. Cost Effectiveness (electricity at $0.045 per kWh) Project
Value of savings ($2005)
Incremental costs ($2005)
Pay-back period (years)
Multiplex arena
22,230
80,500
3.62
Refrigerated warehouse
58,950
252,200
4.28
Food processor
0
51,000
-
Refrigerated warehouse
34,875
168,000
4.82
Food processor
58,770
226,000
3.85
Total
174,825
777,700
4.44
Discussion and Conclusions Program Design and Implementation. Energy efficiency in new commercial buildings is critical because once a building is constructed and occupied, the major building systems may be in place for ten years or more, leading to substantial lost opportunities. The High Performance Building program could address these lost opportunities through a prescriptive program offer that emphasizes energy efficient technology investments in: (1) advanced lighting technologies and lighting controls: (2) energy efficient chillers and HVAC controls: (3) energy efficient mechanical systems including fans, pump and compressors, which offer highly visible savings and rapid pay-back. Building and System Baselines. The present High Performance Building baseline is opaque and causes uncertainties during program design, planning and implementation. There may be advantages in terms of stakeholder understanding and support by moving to a widely accepted and well understood baseline such as the ASHRAE/IESNA 90.1 standard. This may also increase program participation. Design Assistance. Many commercial, institutional and industrial buildings are designed with limited attention paid to energy efficient systems and even less attention paid to integrated, energy efficient design. Energy efficiency considerations often enter the design process when the major mechanical and lighting systems are being designed, which is often too late for an integrated system to be used. Support for early design assistance during the concept phase could help to overcome this barrier. Energy and Peak Impacts. Energy and peak savings were estimated for the five refrigeration projects undertaken during the pilot phase of the program. Since there was no evidence of either free riders or spill over during the process study interviews, the gross and net savings are the same. Energy savings were estimated by the program at 4.8 GWh per year and peak savings were estimated at 1.07 MW. Evaluated energy savings were 3.9 GWh and evaluated peak savings were 0.7 MW. Cost Effectiveness. The pay-back period varies across projects form 3.6 years to 4.8 years. This is within the acceptable limit for most companies in British Columbia.
References [1]
Nadel, S. Packaged Commercial Refrigeration Equipment: A Briefing Report for Program Planners and Implementers. Washington, DC. ACEEE, December 2002.
[2]
Arthur D. Little, Inc. Energy Savings Potential for Commercial Refrigeration Equipment. Cambridge, Mass. 1996.
[3]
Easton Consultants, Inc. Commercial Refrigeration Baseline Study. Stamford, Conn. 1993.
[4]
NYSERDA. Smart Equipment Choices Program Review. Albany, NY. 2002.
[5]
DOE. International Performance Measurement & Verification Protocols. Washington, USA: DOE/GO-102000-1132, October 2000.
[6]
Resources Smart. Energy Efficiency Best Practice Guide: Industrial Refrigeration. Sustainability Victoria, 2009.
[7]
Carbon Trust. Carbon Trust Networks Project: Operational Efficiency Improvements for Refrigeration Systems, 2007.
[8]
Energy Smart. Commercial Refrigeration. Downloaded on December 20, 2009 at www.sedo.energy.wa.gov.au/uploads/comm_refrig_28.pdf.
[9]
Industrial Efficiency Alliance. Industrial Refrigeration Best Practices Guide. Downloaded December 20, 2009 at www.industrialefficiencyalliance.org.
[10]
Reindl, D. Cooler Ideas for Refrigeration System Efficiency. Downloaded December 20, 2009 at www.plantservices.com/articles/2007/188.html.
Heat Pumping and Reversible Air Conditioning in Office buildings Philippe ANDRE1 and Jean LEBRUN2 University of Liège, Department of Environmental Sciences and Management 2 JCJ Energetics 1
Abstract The main objective of IEA Annex 48 is promoting condenser heat recovery and reversible heat pumping in HVAC systems, with help of new design and evaluation tools and through experience gained in cases studies. Heat pumping is a very old idea; its success is mostly depending of the “qualities” of both (“cold” and “hot”) heat sources. Outdoor air is the most common “cold” source, ground is the safest, exhaust air a fairly good one, but with limited capacity and the condenser of another heat pump used in cooling mode is from far the best one, but its availability is limited. Cold storage appears as one of the best way to increase the heat recovery potentials, but it requires a careful design. This paper will, successively, present the basic concepts of the technology used in such applications, explain the tools and methods developed in the course of the Annex and finally present the major learnings obtained from the case studies.
Introduction In late 2005, a new project was launched under the umbrella of the IEA-ECBCS Implementing Agreement (Afjei et al, 2006). This project, numbered Annex 48 was dealing with “Reversible Air Conditioning”. The start of this project was an observation which can be quite often made in office buildings: although heat pumps are there currently used for cooling, they are much more seldom used to cover, even partially, the heating requirements. The technology and the concepts to achieve this task are available but these solutions are not yet fully competing with more classical alternatives made of a heating boiler and of a separate cooling system. The IEA-ECBCS annex 48 project aims to identify the obstacles which prevent a more general application of heat pumping concepts in office buildings and to develop the tools and methods which might help the HVAC designers to make a better use of these solutions. This approach was supported by a number of case studies in several European countries, which helped, on one hand, to better identify the practical problems and, on the other hand, to assess in situ the performance (and sometimes drawbacks) of some implemented solutions.
The heat pump market Vapor compression refrigeration technology is now very robust and the characteristics of all of its components are already well known. Most of the heat pump studies were, until now, concentrated on applications to new (“low” and “very low” energy) residential buildings. In those buildings, heat pumps are usually used in connection with low temperature heating systems (like floor heating systems) and consequently require a sufficient level of thermal insulation of the building. The cooling function, by making these heat pumps reversible, is still relatively marginal, because of smaller demand, lack of incentives and a priori choices which are not always entirely rational… A growing attention is now given to other building types: - Existing residential buildings to be retrofitted; - New and existing non-residential buildings, mostly those presenting some cooling demand (supermarkets, offices…).
In those buildings, a heat pump is usually installed to satisfy the cooling demand. Making the heat pump reversible is not yet a common practice and, except for a few countries in the world, the heat pump market stays, still today, surprisingly marginal… This moderate success might be due to the following obstacles: - Wrong (or non-updated) information: wrong promotions were done in the seventies with poorly efficient heat pump systems, poorly efficient electrical power plants and poorly trained installers. Heat pumps gained a bad reputation at that time… - Some « conservatism »: building designers and engineers tend to promote the techniques they know the best and refrigeration is, for many of them, a bit “mysterious”… - Dissuasive capital costs: a (low tech) residential heat pump is sold today for 10 times the price of a (high tech) car air conditioning! - Dissuasive running costs: Electrical energy, peak of electrical power and maintenance are still too expensive… The IEA-ECBCS “annex 48” project intended to remove these obstacles, thanks to the following actions: - Defining better the heating demands, in relationship with the characteristics of the building, with the climate, with the occupant behavior; - Updating the information about heat pump performances, in relationship with the heat source available and with the heating system selected; - Developing design tools adapted to the different phases of a project, in such a way to guarantee the best integration of the heat pump inside the building - heating system; - Conducting case studies.
The heat pump concept The old dream Heat pump use for space heating is a very old dream, almost as old as the invention of refrigeration cycles. Space heating is indeed only requiring “very low grade” heat (or very little “exergy”), because of the actual temperatures of both (“cold” and “hot”) sources to be considered. This is very favorable to heat pump use... The cold source The cold source can be found in six different (four “outdoor” and two “indoor”) locations: Outdoor air is, still today, the most current “cold” source. It has the inconvenient to become a bit “too cold” at the time of highest heating demand and also to produce frosting, even in milder weather conditions (below around 5°C). Evaporator defrosting is a well resolved technical problem, but the penalty associated to lowest air temperatures is still heavy. Solar energy is sometimes also used as a “booster”: the evaporator can be connected, not to the air, but to a solar collector. This collector has to be sized generously enough to make sure it doesn’t become a bottle neck when there is little or even no solar radiation. Naked collectors are usually preferred for this reason, but this solution stays today very marginal… Surface or underground water is usually considered as the best “external” source: its temperature is relatively high and almost constant (mainly for ground water). But its availability stays rather exceptional and its use is more and more limited by environmental considerations. Fouling and/or corrosion of the heat exchangers can also be a serious problem… Ground itself appears as a very safe, but also very expensive, source: Safe, because, if well designed and well installed, the ground heat exchanger makes no harm to its environment (no pollution, no noise…); Expensive, because it requires large areas (for horizontal exchangers) or deep wells (for vertical exchangers), due to the low thermal conductivity of the ground.
Exhaust ventilation air is also a very attractive source, because of its high and constant temperature, but its capacity is limited and usually insufficient to satisfy the whole building heating demand. Moreover, this option is, at least partly, in “concurrence” with so-called “passive” heat recovery (through a heat exchanger located between exhaust and supply air circuits). The condenser of any refrigeration equipment can be considered as an ideal “internal” source. Such source is even from far the best of all, if it can be used “directly”, i.e. without heat pump, because its temperature is high enough (Dorgan, 1999). In such case, heating can be considered as (almost) “free”. If not, a “templifier” can be added between the existing condenser and the heat using equipment (Hannus et al. 2006). The hot source There are also different options for the hot source: Panel (floor, ceiling and/or wall) heating system is, until now, considered as an ideal source, because of: - low temperature actually required - limited auxiliary consumption - possibility of (short time) energy storage. Other space heating systems, as oversized radiators, fan coils and warm air can also be used, but usually with less good performances, mostly because of (slightly) higher temperatures required, or higher auxiliary consumptions and almost no storage capacity. The so called “VRF” system offers another possibility: the indoor environments of some building rooms can be used as hot sources and other ones as cold sources, thanks to a set of reversible units, actuating as condensers and as evaporators, according to heating and cooling demands. Such system includes an outdoor unit, composed of the compressor associated to a heat exchanger; this one also works as condenser or evaporator, according to the remaining (heating or cooling) demand to be covered. But space heating is not the only one “heat user” inside the building; two other ones are sanitary hot water production (among others in residential buildings) and air humidification. Sanitary hot water production may require a significant rise of the heat pump condensing temperature, which penalise a lot its COP. This may justify the use of a separate system (second stage or completely separate cycle). Air humidification appears to be a problem in some (non residential) buildings: - Adiabatic humidification is ideal in term of energy management (looking to the temperature required), but is questionable in terms of health safety (also because of the low temperature level, favorable to bacteriological contamination). - Steam humidification seems, from other part, fully safe, but energetically inefficient. If actually required for hygienic considerations, it might be realized through a second heat pump stage…
Heat recovery and/or reversibility Heat recovery and/or reversibility techniques have to be selected according to the characteristics of the equipment actually available in the building: Condenser heat recovery requires some connection between the condenser of the refrigeration machine and the heat user (through a warm water distribution circuit, or directly from the condenser to the indoor environment). Such connection is direct in the case of a VRF system. As the amount of heat rejected by the refrigeration machine is very often larger than the building heating demand, a double condenser (or a double condenser cooling circuit) may be required (Aparecida Silva, 2007). Reversibility is understood as the possibility of passing from cold to heat productions with a same system. It can be achieved thanks to some “change over”, performed inside the machine (the evaporator is used as condenser and vice-versa), or in the secondary circuits (inversion between the fluids supplying the condenser and the evaporator, respectively).
These constraints justify a careful analysis of actual heating and cooling demands before making any technological choice in a new building project, or before deciding of any retrofit in an existing system. Both cases deserve careful attention: - New buildings offer the best opportunities with perspective of highest performances (it’s still time for them!); - But the “weight” of existing buildings in global energy and CO2 balances is remaining very heavy in the following decades, because of the slow building renewal rate... Air-cooled chillers are, from far, the most common in existing plants; they don’t offer any heat recovery opportunity, but most of them could probably be made reversible, without too many technical difficulties…
Approach and products of the IEA-ECBCS Annex 48 In order to consolidate the scientific basis to the use of heat pumps in commercial buildings, IEA annex 48 included the following work steps, which, at the end, produced a number of directly associated deliverables. Analysis of heating and cooling demands (Stabat et al, 2009) This analysis is a prerequisite of the evaluation of any heat pumping project. The work concentrated on two types of buildings: office and health-care. For each category, a number of cases were defined, mainly differing by their sizes: -
-
Office buildings: o Type 1: large office buildings (15000 m²), further divided into: § Type 1a: broad open space offices § Type 1b: broad partitioned offices § Type 1c: thin partitioned offices o Type 2: medium size office buildings (5000 m²) o Type 3: small office buildings (1000 ²) Health-care buildings: o Type 1: large hospitals (30000 m²) o Type 2: rest homes (4000 m²)
Each category was further defined in terms of thermal insulation, thermal inertia, solar transmission and orientation. The loads applying in each case were precisely quantified (occupation, lighting, appliances, ventilation and infiltration, heating and cooling set points and domestic hot water consumption (for health-care buildings only). For each combination of these factors, an annual calculation the heating and cooling demands were calculated for 5 climates, selected as representative of Europe (Athens, Lisboa, Torino, Paris, Munich). Examples of simulation results are shown by figure 1. From this large set of simulations, simple indices quantifying the theoretical potential for reversibility and heat recovery were calculated. The definitions of both indices are illustrated in Figures 2 and 3, respectively.
40
maximum heating power of chiller in heat pump mode
30
20
10
priority to the cooling mode
0 0
-10
1
2
3
4
5
6
heating demand
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
40.0
cooling demand reversibility potential -20
20.0
kWk/m²/year
0.0
-20.0
-40.0
-60.0
-80.0
-100.0
type: 1a Orient.: NS Climate: PARIS S olar F: LOW Ventil.: LOW
type: 1a Orient.: NS Climate: TORINO S olar F: LOW Ventil.: LOW
type: 1a Orient.: NS Climate: ATHENES S olar F: LOW Ventil.: LOW
type: 1a Orient.: NS Climate: MUNICH S olar F: LOW Ventil.: LOW
type: 1a Orient.: NS Climate: LISBOA S olar F: LOW Ventil.: LOW
cooling demand
-36.0
-50.2
-78.5
-37.1
-63.2
heating demand
22.2
20.5
6.7
27.9
5.6
Figure 1: Impact of climatic zone on the heating and cooling demands (example: building of type 1a, with a North/south orientation, low solar factor and low ventilation rate)
Figure 2: Reversibility potential calculation
Figure 3: Heat recovery potential calculation
The following conclusions can be drawn from this first analysis: Office buildings offer a high potential of reversible use of the chillers since the maximum cooling power is close to the maximum heating power whatever the building type. Moreover, the potential is more interesting in temperate climates (Mid -North of Europe, France, North of Italy and North of Spain) than in hot climates (periphery of Mediterranean Sea). On the contrary, the condenser heat recovery potential is the most interesting in Southern Europe.
Health care institutions offer a high opportunity of energy recovery, essentially for sanitary hot water. Large hospitals are more interesting than rest homes, since both cooling and hot water demands are larger. The energy recovery for space heating is less interesting in all cases. In large hospitals, with humidity controlled operation room, the potential of recovery for steam humidification is not negligible (up to 1,5 kWh), but much lower than for hot water. The reversibility potential is high in fully air conditioned rest homes. In large hospitals, the reversibility potential is quite high in temperate climate and medium in hot climates (Athens and Lisbon). On the contrary, in partly air conditioned rest homes, the “best” climates for reversibility are Lisbon and Athens.
Review of heat recovery and heat pumping solutions (Bertagnolio et al, 2010a) A systematic review of the major technical solutions allowing the use of heat pumps to satisfy heating and/or cooling demands in buildings was carried out. This review addressed the following points: -
Heat sources and sinks (air, water, ground, solar, industrial processes); System classification: table 1 shows the extensive classification of system types considered in the Annex.
Table 1: Overview of heat pump systems
Nomenclature
Heat pump unit type
Heat source / sink
Exhaust air heat pump
Heat recovery
Reversible air-to-water Reversible brine-to-water
Ground
Yes
No
Refrigerant
Groundwater, surface water
Yes
No
Reversible air-to-water
Extracted air
Yes
No
Extracted air
Yes
No
Split type
Outdoor air
Yes
No
Water-cooled chiller with heat recovery
Water-cooled chiller Dual condenser chiller
Outdoor air (cooling tower) Outdoor air or/and water
·
VRF Decentralized reversible waterto-air
Water Air or refrigerant Refrigerant
Brine
Water
Open/closed water loop
Water
Direct
Water
Direct
Air
Direct
Refrigerant
Non-reversible systems with heat recovery
·
VRF Water-loop heat pump system
Water
Refrigerant
Air-to-air
Reversible (groundsource, groundwater or surface water) heat pump system with heat recovery
Direct
No
Reversible brine-to-water
Reversible water/air-towater Non reversible water-to-water (water-cooled chiller)
Distribution fluid to the building
Yes
Mono-split / Multi-split
Reversible water/air-towater heat pump system
Distribution to the heat source/sink
Outdoor air
Air-to-air dual duct heat pump
Dual condenser chiller
Changeover
Reversible systems without heat recovery
· Reversible air-to-water heat pump Reversible ground source heat pump Reversible groundwater(surfacewater) heat pump
Reversibility
No
Yes
-
Water loop
Water
No
Yes
-
Direct
Water
Reversible systems with heat recovery Outdoor air
Yes
Yes
Refrigerant
Direct
Water
Ground, groundwater, surface water
Yes
Yes
Water
Two separate water loops
Water
Outdoor air
Yes
Yes (3-tubes)
Refrigerant
Direct
Refrigerant
Boiler / Outdoor air (cooling Yes Yes tower) Ground, groundwater, surface water Table 1: Classification of heat pump systems
Refrigerant
Water loop connecting the local heat pumps and the heat source / sink
Two rather popular examples are illustrated by figure 4: the reversible air source heat pump (which is the simplest system) and the exhaust air ventilation heat pump
Figure 4: Two configurations of heat pump systems: reversible air source heat pump (left) and exhaust air ventilation heat pump (right) An important issue in the implementation of reversible heat pump systems concerns the transition from heating to cooling modes. The so-called “change-over” can be operated at the level of the refrigerant circuit (by means of an inverting valve) and/or at the level of the secondary fluid (by means of two or three way valves). Both changes are neither applicable to all systems, nor equivalent, as it can be seen the two configurations presented in Figure 4: - A refrigerant side change over is required to make reversible the air cooled chiller and a water side change over may also be required if the heating and cooling circuits are not compatible; - A water side change over can be sufficient to make reversible a water-cooled chiller, but this adaptation might be even more efficient if “re-using” also all “cooling” heat exchangers (AHU cooling coils and terminal units) for heating…
Development of tools to assess the performances of heat pump systems (Bertagnolio et al, 2010b) A package of simulation tools was developed in order to assess the energy and environmental performances and costs of such solutions. First, a pre-identification tool was developed: this is a “2-minutes- 5 clicks” program, consisting in an Excel-based sheet which only retrieves, using very limited data, relevant results from the generic simulations performed and stored in a database. By comparing the case under analysis and the most similar case in the database, this tool is able to give a first answer to the relevancy of a heat pump project. A second tool allows a quick estimation of the potential of recovery and reversibility options. It consists in comparing computed or measured hourly values of heating and cooling system loads and to compute theoretical reversibility and recovery potentials (Figure 5). Hourly heating and cooling system loads can be generated by means of a calibrated building energy simulation model or obtained through in-situ measurements. This allows the user to make a first selection between the available reversible and recovery systems. A third tool allows to simulate the behavior of the selected heat pump system and to compute its performances using the previously computed hot water and chilled water demand profiles (at distribution network boundaries) as inputs (Figure 5). Only a few parameters are asked to the user (HVAC components rating performance, CO2 emissions per kWh of electricity, weather data…). The heat pump configuration considered is then compared to a classical (boiler and chiller) primary HVAC system, in terms of final and primary energy consumption, CO2 emissions and costs. This evaluation does not take the secondary system into account and provides what can be considered as an upper bound to the performance of the selected solution. This performance can be reduced by the influence of the secondary system with all inefficiencies associated to distribution and control losses.
Figure 5. HP system assessment methodology For final assessment, the use of a detailed simulation program (like TRNSYS) is recommended in order to take the characteristics of the secondary system (and its control) into account. Design guide (Stefan et al, 2010) An important product of the Annex is a tool which provides a global design methodology, starting from comfort requirements, environmental, economical constrains and an analysis of heating and cooling demands. Ecological and economical objectives are evaluated. So the designer can do the best choices at an early stage of a project: architects, consulting engineers and installers should be able to reach a global optimisation of the whole heat pump and HVAC system. This tool includes flow charts and check lists, to help in taking right decisions in right time. The design flow chart is represented in Figure 6.
Figure 6: Methodology proposed by the design guide of the Annex 48
Case studies (Masoero, 2010)
TABS T_supply A
TABS T_supply A
T
T
65 °C
50 °C
TABS cooling
17 °C
District heating
Distributer and collector Three examples are presented hereafter ….
TABS
radiator
TABS heating
radiator heating
domestic hot water
T, p Various case studies were performed in connection with the IEA-ECBCS project. They provided a lot T T of very useful information, but none of them can be yet considered as a convincing demonstration project: in almost each case, the practical conclusion seems to be: “it should work, or it would have T T worked, if…”
cold storage
warm storage
A German case study (Figure 7) allows to learn a lot about the design and submission phases. This T, V case proposes a system configuration which is already quite common in Germany: a ground - coupled reversible heat pump connected, on the buildingT, Vside, to a “Thermally Activated Building System” (TABS). This system is by nature relatively difficult to control and requires a deep commissioning. A number of problems were identified, among others at the level of the hydraulic circuits… T T, V T, V T reversible heat pump p
cold and warm heat exchanger
ground heat exchanger
Figure 7: Ground-coupled reversible heat pump system in connection to TABS An Italian case study also includes a ground coupled heat pump system. This recently completed office building incorporates several energy saving features: high energy performance envelope, reversible GSHP for year-round HVAC, hot and cold phase-change storage, variable-flow water pumps, low temperature heating / high temperature cooling terminals (chilled beams)and green roof. Two water-to-water reversible ground-source heat pumps (GSHPs) provide hot water in winter, and chilled water coupled with recovered hot water in summer operation. The winter heat source / summer heat sink is a geothermal field consisting of 31 borehole (vertical) single pipe heat exchangers, 100 m deep. Two eutectic salt storage tanks are connected in parallel to the GSHPs (one on each side), allowing a significant reduction of installed HP capacity. The HVAC system of the building is relatively complex (Figure 8) and can run in not less than17 different operating modes. ..
Figure 8: HVAC system scheme of the Italian case study One of the Belgian case studies concerns the retrofit of a classical air conditioned office building. The assessment tool applied that case shows promising performances for heat pump used in reversible mode. The results of this analysis are presented in Figures 9 and 10,, with the “model numbers “corresponding to the following system variants: - 0: classical system (boiler + air cooled chiller, used as reference system) - 1: Air to water reversible - 2: Exhaust ventilation air system - 3: Dual condenser - 4: Water loop - 5: Ground coupled HP system
Figure 9: Primary energy consumptions (Belgian climate)
Figure 10: CO2 emission (Belgian climate and Belgian electricity production) Conclusions The following facts and ideas can be extracted from the case studies: - Heat pumping is an expensive technique, which should not be introduced in any new or retrofitting project before having reduced already as much as possible all energy wastes. - In an existing system with water-to-water chillers and cooling towers, it would be cost and energy effective to introduce some water-to-water heat pump (or “templifiers”) in order to recover the condenser heat and to up-grade it until the temperature level required by the heating system. - An existing air-to water chiller can be made reversible and also have a water-cooled condenser added in such a way to allow some heat recovery. - Both reversibility and heat recovery would be made more efficient if taking profit of all heat transfer areas already available in the system. This require some change over: (large) cooling coils of air handling and terminal units can be very well “re-used” in heating mode. - Steam humidification could be performed with the help of a second heat pump stage; this one could use the humidification steam as working fluid (no condenser required: compressed steam would be directly used for air humidification). - Panel heating and cooling is an attractive option, but not applicable in any sort of building; it also deserve a careful design and use of the control system, especially with high inertia structures like TABS. - Manufacturers should optimize more and more their machines for the heating, better than for the cooling, mode. This is not yet the case and most systems are, unfortunately, less efficient in heating than in cooling mode. - As currently done until now, the commissioning of (conventional and unconventional) systems stays insufficient…
Acknowledgment The Belgian contribution to this project has been funded by the Ministry of the Walloon Region of which the support is gratefully acknowledged.
References [1] Afjei, T., André Ph., Halozan H., Lebrun J., Lemort V., Madjidi M., Rivière Ph., Schmid J., Sunye R., Thonon B. Heat pumping and reversible air conditioning: a new project from the Intrenational Energy Agency. Proceedings IEECB 06 Frankfurt, 2006
[2] André, Ph.; Lebrun, J. “Heat Pumping and Reversible Air Conditioning; wWhat we learned from the IEA-ECBCS annex 48 project”. Keynote. ISHVAC 2009, Nanjing, Novembre 2009
[3] Aparecida Silva Cl., Bertagnolio St. et al. (2007) Heat pumping and reversible air conditioning; retrofit opportunities in a laboratory building. ISHVAC 07, Bejing, China, September 2007 [4] Dorgan Chad B. et alii (1999): “ Chiller Heat Recovery Application Guide” ASHRAE project 892 Final Report 1999 [5] Hanus V., Lebrun J., Lemort V., Condenser heat recovery in air conditioning systems. EPIC, Lyon, France, September 2006 [6] IEA-ECBCS Annex 48 http://www.ecbcs-48.org/ [7] Stabat P. André Ph., Bertagnolio S., Caciolo M., Franck P-Y., Rogiest C., Sarrade L. Analysis of heating and cooling demands and equipment performances. Final report of the IEA-ECBCS Annex 48 project, December 2009 [8] Bertagnolio S., Caciolo, M., Corgier, D., Stabat, P. Review of heat pumping technologies. Final report of the IEA-ECBCS Anenx 48 project, February 2010. [9] Bertagnolio S., Gendebien S., Soccal S., Stabat, P. IEA 48 simulation tools: Reference book. Final report of the IEA-ECBCS Annex 48 project, February 2010 [10] Stefan, W., Dentel A., Madjidi M., Dippel T., Schmid J., Gu B. Design handbook for reversible heat pump systems with and without heat recovery. Final report of the IEA-ECBCS Anenx 48 project, February 2010. [11] Masoero M. editor Case studies book. Final report of the IEA-ECBCS Annex 48 project, February 2010
IEECB'10 - Energy Efficiency in Building Equipment
Technology forecast in Lighting regarding Energy Efficiency Wilfried Pohl Bartenbach LichtLabor
Abstract Lighting is a significant energy consumer and causes a serious part of the maintenance costs in buildings. More than 90% of the worldwide running lighting installations are older than 20 years, they are antiquated and inefficient. The retrofit of these installations would increase the lighting quality and simultaneously save most of the energy. In the project IEA Annex45‚ Energy efficient electric Lighting in Buildings‘ [1,2] a survey on existing and emerging lighting technologies (e.g. LEDs, OLEDs) has been made to promote the use of energy efficient and high quality lighting technologies. The author was the leader of Subtask B‚ Innovative Lighting Technologies‘, where the different trades transforming electric energy in visual environment have been analysed and their energy saving potentials have been estimated. A future scenario of lighting technologies in use has been drafted and the resulting energy consumptions have been calculated. The forecast shows that there is a big energy saving potential, and it is realistic to achieve a decreasing energy consumption for the future, and at the same time consume more light. Aiming at saving energy we should not forget the goal of the system: to lighten a space according to architectural and visual requirements, thus increasing our living quality.
Lighting energy It is estimated that ca. 20% of the worldwide electric energy consumption is used for lighting, and we are facing an increase of ca. 2-3% each year in the developed countries [3]. In the realms of the EU-building guideline »Energy Performance of Buildings Directive« 2002/91/EC (EPBD) [4] special standards are under development aiming to establish conventions and procedures for the implementation of the EPBD into lighting practice, e.g. the EN15252 [6] and EN15193 [7], which takes the power requirements for electric lighting into consideration and places limit-values thereupon. In the standard limit-values for the different building types are given. These limit-values refer, on the one hand, to connected loads (in W/m²) and on the other hand to energy consumption over a particular period of time (mostly one year, indicated in kWh/m²year) [5]. The EUP directive 2005/32/EG (Energy Using Products) from August 10th 2007 forces lamp industry to phase out inefficient lamps from the market, and one result of this regulation is the ban on the GLSbulb (picture below). And on April 22nd, 2009, the European parliament voted that all new buildings from 2019 forward have to fulfill the standard for Zero-energy buildings. Zero-energy buildings are buildings that produce as much energy as they consume and represent the cutting edge of energy efficiency in buildings. Whereas in common buildings the electric energy consumption for lighting may be comparable small, for such low or zero energy buildings the demand for electric energy for artificial lighting becomes a decisive matter. If we consider that GLS bulbs (incandescent, ca. 12lm/W efficacy) consume ca. 30% of the electric energy for lighting (producing less than 10% of the light!), and that ca. 20% of the electric energy for lighting is consumed by antiquated T12 (38mm diameter) fluorescent tubes (less than 50lm/W, including ballasts) we can estimate the huge saving potential by replacing these lamps by new lamp types with 80lm/W or more [2] !
Figure 1: GLS bulb (left) and a fluorescent tube (right)
Quality of Lighting Evaluating economics and energy aspects of a lighting solution we never have to forget the goal of the system: to lighten a space regarding to the visual and aesthetical requirements of the occupants. Adequate illuminance and luminance levels horizontal and vertical (regarding on the room utilization, visual tasks, etc.), proper balanced luminances in the field of view, control of direct and reflected glare, and adequate color rendering are minimal conditions for a good lighting. The Lighting quality (‘climate’) is not measurable, but there are a few criteria (measurement values) which enable to assess the quality: - Horizontal illuminance distribution - Vertical/zylindrical illuminance distribution - Luminances in the field of view - Colour temperature and colour rendering indexes - Glare - Radiation field (light directions, shadowing, contrasts). - Flicker frequency - Daylight. The European standard EN12464 ‘Light and Lighting – Lighting of work places’ gives guideline and boundary values for these criterias [8]. Table: Examples of requirements for different room types and tasks acc. to EN12464 Room type resp. visual task Office floors writing, reading technical drawing Restaurants Parking garage, way in and out Health Care Surgery Rooms Autopsy
Emean
UGR
Min. Ra
100 500 750
28 19 16
40 80 80
-
-
80
300
25
20
1000 5000
19 -
90 90
The minimal illuminance on the task area is Emean, the glare is evaluated with the unified glare rating (UGR) method, and the colour rendering featurers are measured by the Ra index.
From electricity to brightness (visual environment) In lighting we can identify three groups of trades, which transform electrical energy into light, starting with the power connection (grid) and ending with the luminances of the room surfaces (visual environment): the lamp (light source, including controls and ballasts), the luminaire, and the room. The lamp transforms electric power into light flux, the luminaire distributes the light in the room, and the room transforms this light into visible luminances by the surface reflections. The energetical performance of these different transformations are characterized by the factors - lamp efficacy (in lm/W, including operating device) - luminaire light output ratio (LOR, in %) - room utilization factor (RUF, in %). The ‘sum’ of these factors gives the ultimate (total) utilization of the electric light installation. The energy consumption of the installation is further defined by the operating times, i.e. the need for artificial lighting should be minimized by intelligent architecture and daylight harvesting. To avoid needless operating of the artificial light proper controls (occupancy, daylight dependence, etc.) has to be installed [6,7,8,9]. A key point in energy efficient lighting design is the choice of efficient lamps, which produce the proper spectrum (colour temperature Tf and colour rendering Ra) and offer the required operating features. At the moment fluorescent lamps dominate in office lighting, but 55% of the connected power is the antiquated T12 (38mm diameter) lamp. The new generation of linear fluorescent lamps, the T5 (diameter 16mm), together with high frequency ballasts, allows us to increase energy efficiency and decrease the costs at the same time, compared to the old magnetic ballasts and T12 and T8 techniques. In domestic lighting the dominant light source (>80% connected power) is the inefficient GLS bulb (incandescent lamp, 12lm/W), consuming ca. 30% of the electric energy for total lighting. Replacing them by CFL’s, IRC tungsten halogen lamps, and by LEDs, could save most of the energy use for residential lighting. Beside the use of high efficient lamps the application of high quality luminaires with efficient lighting concepts and controls is important for the visual and ecologic quality of the whole lighting. A luminiare is a device to operate the lamp. It is a complete lighting unit, which comprises the light source including electric operating devices (transformer,ballast, ignitor), together with the parts that position and protect the lamp(s) (casing, holder, wiring) and connect the lamp(s) to the power supply, and finally the parts that distribute the light (optics). The luminaire’s function (if not a pure decorative fitment) is to direct light to appropriate locations, creating the required visual environment, without causing glare or discomfort. Different lamp technologies require different luminaire construction principles and features. For example, a metal halide lamp HCI 150W (extreme high power density, very small, luminance 20 Mio cd/m2, bulb temperature ca. 600°C) compared with a T-8 fluorescent lamp HO35W (diameter 16mm, 1,5m long, surface temperature 35°C, luminance 20.000cd/m2) require completely different luminaire types.
Figure 2: Circular fluorescent fitting with secondary radiation technique and high quality shielding.
The efficiency of a luminaire is characterized by the light output ratio (LOR), i.e. the ratio
The efficiency (LOR) of a luminaire depends mainly on the lamp with electronic operating device and on the optical components. Recent developments of high reflective (high specular or diffuse) surfaces for lighting purposes, of complex surface calculation methods and of new manufacturing technologies (e.g. injection molded plastics with Al-coating) has improved the efficiency (light output ratio) of luminaires (reaching 80% or more), also the emerging LED-technique will follow this trend.
Figure 3: Inefficient lighting solution (left), lack on control (right) The room utilization RUF factor, which is the last factor in the efficiency chain, depends amongst others on the room surface reflectances: e.g. for a room with a mean reflectance of • mean = 20% the additional indirect lighting (by multiple room surface reflections) is only 8% of the direct lighting, whereas for a mean reflectance of • mean = 70% it is 70% ! Most of the running lighting installations (ca. 90%) are older than 20 years, i.e. that these installations use antiquated and inefficient lighting equipment. Replacing these inefficient installations by energy efficient components (lamps, controls, ballasts and luminaires) is a huge energy saving potential, and in parallel the lighting quality could be improved [2].
LEDs Light Emitting Diodes (LEDs) are undoubtedly the most revolutionary innovation in lamp technology since decades. Powered meanwhile by several Watts, emitting white light with an efficacy of more
than 50lm/W (and envisaging 100lm/W), and with a colour rendering index (CRI) greater than 80, they will soon outperform most traditional lamps. The benefits of LEDs are a long lifespan up to 100.000h, colour mixing possibility (flexible colour temperature Tf), ‘cold’ spectrum (no infrared), design flexibility and brilliant light due to its small size, easy control and dimming, safety due to low-voltage operation, ruggedness, and a high efficacy (lm/W) compared to incandescent lamps. Due to the low prices and high lumen output fluorescent tubes with an efficacy of > 100lm/W and life spans > 20.000h are the most economic and wide spread lamps, more than 60% of the artificial light is generated by this lamp type today. Compared to this, LED’s are expensive and offer a much lower light output. The gap between conventional light sources and LEDs is decreasing but at the moment still too large for economical lighting. Only for the GLS-bulb and the tungsten halogen lamp, the most used lamp types in homes, with a very low efficacy ( 20Miocd/m2), with extremely low thickness (a few millimeters) and flexibility in shape. They can produce high-quality and tailored spectra (coloured and white, dependent on the application), and they will be very efficient (the expected long-term efficacy is more than 100lm/W).
Figure 4: Small OLED examples [10]
Life cycle costs For economic evaluation of different lighting solutions a life cycle cost analysis has to be made, this means, that all cost categories including initial (installation) and future costs (operation costs like maintenance and energy) must be considered over the lifetime of the whole lighting installation [5]. Initial costs are e.g. costs for the lighting equipment, wiring and control devices, and the labour for the installation of the system. Future costs may include relamping, cleaning, energy, replacement of other parts (reflectors, lenses, louvers, ballasts, etc.) or any other costs that will be incurred. Usually only installation costs are taken into account, people are not aware of the operation costs, and in commercial buildings very often the operation costs are paid by others than the initial cost which are usually paid by the investor, who makes the system decisions. Especially the energy costs of a lighting installation during the whole life cycle very often are the biggest part of the whole costs. Similar results can be calculated for offices or other commercial buildings. For a more precise calculation you have to take into account interest rates and increasing prices for energy and service [2], especially the latter will increase the fraction for energy costs significantly.
Maintenance All system components are aging, and must be replaced at certain times (before dropping out). Lamp performance decreases over time before failure (see figure), and dirt accumulations on luminaires and room surfaces decreases the utilization factors. Lack of maintenance has a negative effect on visual perception, human performance, safety and security, and wastes energy. Both effects, aging and dirt depreciation can reduce the whole efficiency of a lighting installation by 50% or even more, depending on the application and equipment used. The following measures should be defined by a regular maintenance schedule: Ø cleaning of luminaires, daylighting devices and rooms (dirt depreciation) Ø relamping (usually before burn-out) Ø replacement of other parts
Ø renovation resp. retrofitting of antiquated systems and components.
Figure 6: Lamp light flux depreciation during life time (principal sketch).
Recommendations for energy efficient lighting The European standard EN15193 ‘Energy performance of buildings – Energy requirements for lighting’ defines procedures for the estimation of energy requirements of lighting in buildings, and provides guidance on the establishment of national limits for lighting energy based on reference schemes [7]. To design energy efficient lighting solutions the designer should perform life-cycle cost evaluations and economic evaluations (including payback criteria desired by the building owner). The following rules should be kept in mind to reach or supersede these goals: 1. intelligent architecture and facade construction (use of daylight) 2. efficient lighting concepts (bright surfaces, use of high quality luminaires and lamps) 3. proper controls (on/off, daylight, occupancy) 4. proper maintenance.
Electric energy consumption forecast The estimated global electric light consumption (quantity of light Q in lmh, produced by lamps) is shown below. The biggest share of light consumption, 11,3 Mlmh/pers,a, is consumed by linear fluorescent lamps (LFL) followed by HID lamps with 5,4 Mlmh/pers,a. largest proportion of 11.2 Mlmh/person/year is produced by linear fluorescent lamps followed by HID lamps with 5.3 Mlmh/person/year. Incandescent lamps have a comparably lower share.
Figure 7: Estimated electrical light production 2005 (by end user and lamp type) [2,3]. In Figure 8 the proportion of electric energy consumption of the different lamp types for each sector is represented. The high share of energy consumption of the incandescent lamps, due to their low efficacy, is very distinctive.
Figure 8: Estimated electrical power consumption 2005 (by end user and lamp type) [2,3]. In the following Figure 9 one can see the halving of energy consumption up to the year 2015, mainly due to the phasing out the GLS bulbs and low efficient tungsten halogen lamps, due to the replacement of the T12 fluorescent tubes, and due to increased light yield of all lamp types and luminaires [2]. The forecast of the electric energy consumption is based on the assumptions - increasing light demand of 25% (2015) and 55% (2030) of end user - increasing efficiencies of the installations of 0.80 (2015), espectively 0.75 (2030) (LOR of luminaires, room utilization) - reduced operating times (by daylight utilisation and controls) of 0,80 (2015), respectively 0,70 (2030) - phasing out incandescent (mostly until 2015), T12 (2015) and T8 (2030) lamps, replaced by CFL, LFL T5 and LEDs. As the proportion of tungsten halogen lamps remains relatively unchanged, but their light yield slightly increases, their energy consumption will sink minimally. This is similar with the HID lamps. The proportion of compact fluorescent lamps will increase and at the same time, their light yield will increase, therefore resulting overall in a lower total energy consumption. Furthermore, for the year 2030, there will be a further reduction in the use of incandescent lamps due to the almost complete replacement by tungsten halogen lamps and compact fluorescent lamps, due to an increased yield and with regard to fluorescent lamps and HID lamps, due to the replacement of obsolete technology. LED’s will penetrate further into the market and will have a corresponding share.
Figure 9: Development of electric energy consumption from 2005 to 2030 [2]
Conclusion If we would realize the technical potential for energy savings we not only could limit the yearly growth of electric power consumption for lighting, we rather could halve the total energy consumption of nowadays until 2015! In the above defined (realistic) scenario one can see a big decline in the future energy consumption although the lighting demand is increasing. This reduction is mainly due to the phasing out of incandescent lamps, to the replacement of the T12 (and low efficient T8) fluorescent tubes, and due to increased light yield of all lamp types, luminaires, and installations. Taking these assumptions for granted we can expect a decrease in electrical energy consumption for lighting down to less than a half of the consumption of 2005. These assumptions and also the forecast of lamp efficacies are rather conservative for the developed countries. The remaining unknown is the development in China, India and Africa, that will define if the predicted energy savings become reality. So there is no reason to abandon the quality requirements, in lighting we are in the lucky position to do both: save energy and increase the quality of light (= visual environment) !
Acknowledgement (for IEA ECBCS Annex 45) The International Energy Agency (IEA) is an intergovernmental body committed to advancing security of energy supply, economic growth and environmental sustainability through energy policy cooperation. IEA has Implementing Agreements (IA) to organize research. One of these IAs is Energy Conservation in Buildings and Community Systems (ECBCS). The function of ECBCS is to undertake research and provide an international focus for building energy efficiency. Tasks are undertaken through a series of annexes that are directed at energy saving technologies and activities that support their application in practice. Results are also used in the formulation of energy conservation policies and standards.
The Executive Committee of the ECBCS program established a new Annex in June 2004 called Energy Efficient Electric Lighting for Buildings, which will be finished this year. The objectives of Annex 45 are to identify and accelerate the use of energy-efficient high-quality lighting technologies and their integration with other building system, to assess and document the technical performance of existing and future lighting technologies, as well as to assess and document barriers preventing the adoption of energy-efficient technologies, and to propose means to resolve these barriers. The author is the leader of Subtask B in Annex 45, which is focused on innovative lighting technologies and its potential for saving energy. The work was funded by the Austrian Federal Ministry for Transport, Innovation and Technology (Bundesministerium für Verkehr, Innovation und Technologie, BMVIT).
References [1]
http://www.lightinglab.fi/IEAAnnex45
[2]
Guidebook on energy efficient electric lighting, IEA, Annex 45, publication pending
[3]
Light’s Labour’s Lost. International Energy Agency IEA Publications, France
[4]
EC (2002). Directive 2002/91/EC of the European Parliament and of the Council of 16 December 2002 on the energy performance of buildings (EPBD)
[5]
Project EIE-07-190 ‘Comfort monitoring for CEN standard EN15251 linked to EPBD’ COMMONCENSE
[6]
EN15252 European standard ‘Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics’
[7]
EN15193 European standard ‘Energy performance of buildings – Energy requirements for lighting’
[8]
EN12464 European standard ‘Light and Lighting – Lighting of work places’
[10]
www.oled100.eu
Theoretical Comparison of Innovative Window Daylighting Devices for a sub-tropical climate using Radiance Michael Hirning, Veronica Garcia Hansen, John Bell Queensland University of Technology Abstract Daylighting in tropical and sub-tropical climates presents a unique challenge that is generally not well understood by designers. In a sub-tropical region such as Brisbane, Australia the majority of the year comprises of sunny clear skies with few overcast days and as a consequence windows can easily become sources of overheating and glare. The main strategy in dealing with this issue is extensive shading on windows. However, this in turn prevents daylight penetration into buildings often causing an interior to appear gloomy and dark even though there is more than sufficient daylight available. As a result electric lighting is the main source of light, even during the day. Innovative daylight devices which redirect light from windows offer a potential solution to this issue. These devices can potentially improve daylighting in buildings by increasing the illumination within the environment decreasing the high contrast between the window and work regions and deflecting potentially glare causing sunlight away from the observer. However, the performance of such innovative daylighting devices are generally quantified under overcast skies (i.e. daylight factors) or skies without sun, which are typical of European climates and are misleading when considering these devices for tropical or sub-tropical climates. This study sought to compare four innovative window daylighting devices in RADIANCE; light shelves, laser cut panels, micro-light guides and light redirecting blinds. These devices were simulated in RADIANCE under sub-tropical skies (for Brisbane) within the test case of a typical CBD office space. For each device the quantity of light redirected and its distribution within the space was used as the basis for comparison. In addition, glare analysis on each device was conducted using Weinold and Christoffersons evalglare. The analysis was conducted for selected hours for a day in each season. The majority of buildings that humans will occupy in their lifetime are already constructed, and extensive remodelling of most of these buildings is unlikely. Therefore the most effective way to improve daylighting in the near future will be through the alteration existing window spaces. Thus it will be important to understand the performance of daylighting systems with respect to the climate it is to be used in. This type of analysis is important to determine the applicability of a daylighting strategy so that designers can achieve energy efficiency as well the health benefits of natural daylight. Introduction Lighting affects the appearance of a space and its occupants’ mood and productivity level [1,2,3]. Lighting in commercial buildings should enable workers (who typically spend one third of their waking hours there) to perform their required tasks effectively [4]. At present, the concern over climate change is driving a renewed interest in the development of daylighting practices for energy efficient lighting purposes. Daylighting is the controlled admission of natural light into a space to reduce or eliminate the need for electric lighting. It offers environmental, economic and social benefits when applied successfully; however, poor use of daylight causes unwanted heat and glare problems that negate any desired benefits. In order to develop effective daylighting practices, it is necessary to have a thorough understanding of how particular daylighting devices will affect a space and its occupants before installation. The main aim of this study was to theoretically analyse four daylighting devices that may be applicable for use in windows of commercial buildings in a sub-tropical climate. This was done using computer simulations in RADIANCE [5]. The use of simulations to understand our natural and built world has become increasingly popular with the advancement of computer technologies and their software. Simulating daylight to create aesthetically improved or more efficient daylighting design in buildings is common among researchers and designers [6,7]. Simulations provide a few notable advances over
either scale building or laboratory testing. Computational analysis of daylight is less expensive than building scale models and it can provide more accurate data on the illumination within a building. Conducting controlled experiments is easier with simulations as daylight is a highly variable and rapidly changing light source. A disadvantage though, is that a simulation is less tangible than real scale model. Any errors or shortcomings which would be physically visible in a scale model are less easily diagnosed in simulations where the entire calculation process takes place behind the scene. The simulation of daylight in this study was conducted using the RADIANCE simulation environment. RADIANCE is a highly accurate physically based backwards ray-tracing software system for UNIX [5]. This means when conducting simulation, at each specified point of calculation lights rays are traced from the detector backwards to a known light source, to determine either the illuminance or luminance. This makes the program more efficient than forward raytracing programs because it doesn't trace rays that will eventually be blocked from reaching the detector. It is primarily used for architectural and research lighting simulations. RADIANCE is not so much a program itself, but a small collection of programs that facilitate accurate simulation and visualisation of lighting. It is the software of choice for the majority of lighting researchers and is increasingly popular among lighting consultants, architects, and interior designers. However RADIANCE is generally considered very user unfriendly which has led to its less than rapid acceptance by a wider community. Daylighting In Sub-tropical Climates There is a great variation between sky conditions in sub-tropical climates and those in Europe and USA. Most daylighting research is conducted in Europe and daylighting technologies, lighting calculations and simulations have been developed for these climates [8]. In Brisbane, sky conditions are representative of a temperate sub-tropical climatic zone; warm and temperate conditions along the coastal strip. This means the sky is mostly clear or partly cloudy all year round, there are no great variations in climatic conditions between seasons [9]. In general, bright skies and hot climates mean daylighting is not the main concern in building design. Extensive shading devices and small window openings are employed as the main features of building design to control excessive penetration of direct sunlight to reduce heat gain and glare (Figures 1 and 2). In addition, generally windows are only single pane, unlike in Europe (Figures 3 and 4) where the majority of buildings are double glazed, which greatly affects the thermal heat transfer through windows. Therefore, the amount of daylight entering windows is severely reduced by these strategies and internal daylight levels in shaded subtropical buildings are well below those achieved in buildings in more temperate climates [9]. By defining the characteristics of tropical and sub-tropical skies, sky distribution models that better represent the conditions can be used for simulation and analysis to obtain more realistic results, giving rise to more appropriate daylighting solutions.
Figure 1 (left) and Figure 2 (right): Office buildings in Brisbane (a sub-tropical climate) employ significant shading strategies to reduce potential glare and solar heat gain, consequently interiors appear dark and gloomy and rely solely on electric lighting. Daylighting Devices
A laser cut panel (LCP) is a daylight redirection system (Figure 5) that is made by laser cuts in a thin panel of acrylic material [10]. These laser cuts work by deflecting a fraction of the incoming light through total internal reflection at the surface of the cuts (Figure 6) [10]. The remaining light passes through the panel undeflected [11]. LCP's perform better in climates with clear sky conditions, deflecting direct sunlight into the ceiling avoiding direct sunlight on the workplane. Little maintenance is required and they can increase the natural
Figure 3 (left) and Figure 4 (right): European office buildings employ large double glazed windows with little to no shading. The daylight penetration in these buildings is much higher than those in Figures 1 and 2. illumination in the deep space of a room [11]. A simple algorithm based on the RADIANCE ‘prism2’ material allows quite complex arrangements of LCP's to be simulated [12].
Figure 5: A laser cut panel (LCP) [10].
sunlight redirected sunlight laser cut panel light from
double
reflection
Figure 6: Light path through a vertically installed Laser Cut Panel.[13,14] The micro-light guides (MLG's) are made of nine small light guides (Figure 7). Each guide contains two metal reflectors, one flat and one parabolic which form an aperture and a guide. Translucent panels are placed over the front and back of the guides to protect it from dust. MLG's have been shown to be an improvement on light guiding shades [14]. The system increases the illumination of interiors in comparison to windows with shading. They also avoid glare if placed above eye level, and can help reduce cooling load.
Figure 7: MLG panel in facade (left). Light path through a micro-light guiding element (right) [14,15]. The MLG has been optimised for sub-tropical climates and there are developed RADIANCE algorithms for modelling both LCP's and MLG's [14,15], with both simulated models in agreement with test field measurements.
Figure 8: An installed internal light shelf [16] A light shelf (Figure 8, Figure 9) is a horizontal or nearly horizontal baffle that reflects light into a building off its top surface whilst shielding direct sunlight [13,16]. Under direct sunlight a window with a light shelf can give higher illuminances near the back of a room than just a window, reducing the contrast in the space due to the illuminance reaching the workplane from different sources.
redirected daylight light shelf view window
Figure 9: Path of light through an internal/external light shelf system [13]. Ochoa and Capeluto [17] studied many innovative daylighting systems in a sub-tropical area and investigated their daylighting and shading potential. The study found that the lightshelf ‘‘provided a safer approach by reducing contrast between levels at the view window and those at the back of the room, yet sacrificing on illuminance levels”. Extensive modelling in RADIANCE of light shelves with different geometries in test rooms with different ceiling geometries has already been undertaken [7]. It was found using an external curved lightshelf increased illuminances levels in the back of the room and improved uniformity. Light redirecting blinds (LRB) work in the same manner as the other light redirecting devices mentioned previously. Highly reflective metal louvres of a venetian blind redirect incoming sunlight towards the ceiling (Figure 10) [18]. However unlike the other devices considered here, LRB's are not integrated into the structural design of the window and building. They are located behind the existing window. This makes them easier to install and thus a more cost effective solution for retro-fitting in existing buildings. The tilt angle of LRB is also easily controlled by occupants to maximise their effectiveness but this will not be investigated.
redirected daylight LRB
Figure 10: Light redirecting blinds (LRB) installed behind window [18]. RADIANCE Model Test Room The State Government Executive building located in George St, Brisbane, Australia is a high rise office building considered to be a medium to deep plan building (Figures 11 and 12). It is a typical multi-story office block for Brisbane.
Figure 11 (left) and Figure 12 (right): George St Government Office Building. Geometry of the test room is based on rooms mid-way along the building in Figure 12. rd
For the simulations a typical room located on the 3 floor (10m high ~ 3 storeys), midway along the exterior of the building was chosen as a 'test room' for the comparative simulations (Figure 12). The width and length of the test room measures 5m and 8.5m respectively. The standard convention of reflectance's used in artificial lighting simulations (70% ceiling, 50% walls, 20% floor) was used for the test room. The room has three windows each 1.366m in width, 1.66m in height. The windows are separated from each other by a thin metal window frame. The room will be orientated north as this will be the most effective orientation for daylight redirection. Sky Description The sky used for every simulation is the CIE clear sky with sun model adjusted for Brisbane's location (latitude -27°, longitude 153°). Brisbane has a sub-tropical climate and on average (for the past 10 years) has around 228 sunny days a year (137 with no clouds) thus the clear sky with sun model is the most relevant sky description to use [19]. A sky description was generated for selected dates and times in three seasons. These dates were; st − 21 December (Summer) st − 21 June (Winter) st − 21 September (Spring) For each of these dates a sky description was created for 9am, 1pm and 4pm. Device descriptions The generic windows are used in each simulation as a base case for comparison. The windows used were single pane 8mm clear float glass with a transmission of 88%. Each light redirecting device was situated at least 2m above the floor, so as to avoid directly redirecting light up into an occupants eyes. The MLG's, LCP's and LRB's used in the simulation are each 53cm high (approximately one third of the original window height) and expand the width of the windows. The laser cut panels replace the top section of window (Figure 6), while the micro-light guides sit at a 30 degree angle out from the top of the window (Figure 7). The LRB's are within the room and sit just behind (10mm) the top section of window (Figure 10). The descriptions of the micro-light guides and laser cut panels were adapted from the work of Greenup [14]. The micro-light guides are made of eight small light guides. Each guide contains two metal reflectors, one flat and one parabolic which form and an aperture and guide. Translucent panels are placed over the front and back of the guides to protect them from dust. The metal reflectors are made from silver coated aluminium with a specular reflectivity of 95%. The translucent material covering the front or input of the micro-light guides is a translucent material with about 80% diffuse transmittance. The output panel is highly transparent glass (91% transmittance). The laser cut panels are defined in RADIANCE as an acrylic prism with a refractive index of 1.5. They have a cut depth (thickness of panel) to cut height (vertical distance between cuts) ratio of 0.5 i.e. for panel thickness ~ 8mm, distance between horizontal cuts is ~ 4mm. Sitting in the window the LCP will deflect part of the light towards the ceiling and the rest will be transmitted undeflected. Since the lasercut panels and micro-light guides are 53cm high and sit in the top section windows the light shelf was designed to be as equivalent as possible to these other light redirecting devices. The light shelf again sits 53cm below the top of the window, and is made of two sections, both 0.3m wide (similar to Figure 9). One section sits on the outside of the windows perpendicular to them, the other equivalent section sits inside the windows. The light redirecting or upper surface of the light shelf is made of an 85% diffusely reflecting white plastic material, while the lower surface or light shading surface of the light shelf is made of a 40% diffusely reflecting white plastic material. The LRB's are made of a highly reflective metal slate material (70%). The blinds sit 10mm on the inside of the window and cover the top 53cm section of window (similar to Figure 10). The each slat is inclined at 30 degrees to the vertical. The model for the LRB was generated in LBNL's Window 6 program [20]. The program allows creation of custom shadings,windows and venetian blinds. Using Window 6 a bi-directional scattering distribution function (BSDF) was calculated. A BSDF gives the
light output distribution of the window and LRB combination. RADIANCE has recently been modified to use this data in its raytracing algorithms to more accurately simulate window elements of this type [21]. Calculation Process Within the simulation room a grid of collection points that were evenly spaced about 25cm apart throughout the room was used. This included a 0.5m wall zone and the grid was situated on the workplane at 0.7m above the floor. The illuminance at each point was calculated using RADIANCE. Using this data the average illuminance, maximum illuminance and uniformity (min/ave) was calculated (Table 1). Also using this data the illuminance in the plane parallel to the window (across the front) was plotted against distance from the window (Figures 13 to 17). These graphs allow easier visualisation and comparisons of the daylight penetration and distribution throughout the room. The purpose of these simulations is to compare different daylighting devices with respect to their lighting performance using typical room geometries of already constructed real buildings, in this case the geometries of the Government Office Building located in George St, Brisbane. The five daylighting devices that were simulated are; − clear float single pane windows − micro-light guides − laser cut panels − light shelves − light redirecting blinds The simulation is conducted by translating an architectural model into a RADIANCE scene file. From this point on the description of the sky and daylighting devices must be manually coded in RADIANCE. With descriptions of the sky, daylighting devices and building, a lighting simulation can be performed. Results Table 1 shows the lighting performance of each daylight redirecting device with respect to the average and maximum illuminance as well as the uniformity (min/ave). Winter
Spring
Summer
Winter
Spring
Summer
Winter
Spring
Summer
Average Illuminance Win 10am: 7.50E+03 1pm: 9.18E+03 4pm: 2.17E+03 10am: 3.61E+03 1pm: 4.40E+03 4pm: 9.62E+02 10am: 5.56E+02 1pm: 6.47E+02 4pm: 4.37E+02
(lux) MLG 5.98E+03 7.20E+03 1.97E+03 2.17E+03 2.55E+03 8.18E+02 6.28E+02 7.45E+02 4.23E+02
Maximum Illuminance Win 10am: 2.81E+04 1pm: 4.06E+04 4pm: 8.42E+03 10am: 3.82E+04 1pm: 4.79E+04 4pm: 8.97E+03 10am: 2.04E+03 1pm: 2.45E+03 4pm: 1.50E+03
10am: 1pm: 4pm: 10am: 1pm: 4pm: 10am: 1pm: 4pm:
(lux) MLG 2.79E+04 4.06E+04 8.24E+03 3.50E+04 4.95E+04 4.97E+03 2.36E+03 2.76E+03 1.44E+03
Uniformity (Min/Av) Win 0.054 0.045 0.110 0.060 0.051 0.139 0.238 0.233 0.251
MLG 0.057 0.054 0.106 0.131 0.128 0.180 0.204 0.207 0.225
LCP 6.47E+03 7.64E+03 2.19E+03 2.87E+03 3.60E+03 8.50E+02 5.58E+02 6.43E+02 4.33E+02
LS 5.05E+03 5.50E+03 1.98E+03 9.92E+02 1.07E+03 5.62E+02 6.14E+02 6.98E+02 3.99E+02
LRB 7.36E+03 9.13E+03 2.12E+03 3.54E+03 4.41E+03 8.89E+02 4.60E+02 5.32E+02 3.56E+02
LCP 3.05E+04 4.41E+04 8.78E+03 3.92E+04 4.91E+04 9.06E+03 1.98E+03 2.38E+03 1.48E+03
LS 2.79E+04 4.06E+04 8.06E+03 3.05E+03 3.26E+03 3.04E+03 1.83E+03 2.10E+03 1.24E+03
LRB 2.78E+04 4.07E+04 8.38E+03 3.79E+04 4.79E+04 8.78E+03 1.70E+03 2.03E+03 1.28E+03
LCP 0.058 0.052 0.106 0.075 0.063 0.148 0.238 0.235 0.249
LS 0.063 0.062 0.103 0.190 0.188 0.204 0.227 0.225 0.257
LRB 0.044 0.041 0.096 0.057 0.053 0.121 0.223 0.224 0.218
Table 1: Daylighting performance of each light redirecting device for all simulated seasons and times. Table 1 shows that overall the light shelves provided the best uniformity overall, followed by the LCP's, MLG's, Windows and LRB's. The maximum illuminance achieved by each device was very similar, but this is to be expected with unobstructed daylight penetrating through the lower two thirds of the window. The average illuminances achieved were also very similar as well as expected, with windows generally achieving higher averages than LRB's, MLG's, LCP's and LS's respectively. To more easily visualise the above presented data, selected graphs of seasons and times that show significant results are presented below (Figures 13 to 17).
Figure 13 (left) and Figure 14 (right).
Figure 15 (left) and Figure 16 (right).
Figure 17. All light redirecting devices performed optimally in Spring. The daylighting devices considered in this study were designed to not be adjusted and so Spring and Autumn are a compromise between the extremes of the summer and winter solar elevations. Figures 13 and 14 show that the light shelves significantly shade direct sunlight from the room, as suggested previously, at the sacrifice of illuminance levels in the back of the room [17]. The same figures show the MLGs provide some shading as well as significant light redirection, achieving the best levels overall in the back of the room. The laser cut panels perform better than other devices in winter and summer. LCP's provide a more consistent light distribution all year round. The LRB's appear to have a significantly reduced performance in Summer. This is due to the LRB's being mounted behind the window. In summer the high angle daylight isn't reaching a significant portion of the blinds and is unable to be redirected. The raw data presented here gives an indication of the daylight penetration and distribution within the test room and allows for easier comparison of the devices. However, the data presented in Figures 13 to 17 are smoothed averages and don't allow us to see the actual distribution and what the devices look like integrated into the window. Figures 18 to 22 are selected high dynamic range images and luminance maps of the devices at 1pm in Winter. The point of view is for an occupant sitting (eyes 1m from ground) in the centre of the room (4.25m from window) looking almost directly at the window. The generated luminance maps were also used for the glare analysis presented below. The maximum and minimum luminance is displayed on the image.
Figure 18 (left), Figure 19 (middle) and Figure 20 (right): Contour luminance maps of Windows, MLG's and LCP's.
Figure 21 (left) and Figure 22 (right): Contour luminance maps of Light Shelf and LRB's. All fisheye HDR images were analsyed with the RADIANCE based program evalglare [22]. It would be expected from the mounting height (> 2m) of the daylight redirecting devices that there would be no sunlight directed towards any occupants and thus no significant glare from the daylighting devices. The daylight glare probabilty (DGP) index as calculated by evalglare for the above images is shown below (Table 2). DGP
Window 0.36
MLG 0.64
LCP 0.35
Light Shelf 0.33
LRB 0.36
Table 2: DGP index as calculated for Figures 18 to 22. Table shows all devices performed in a similar manner and did not produce any glare except the MLG's. Specular reflections can be seen from the individual metal guides of the MLG's. At particular times of day an image of the sun can be seen in the aperture of the MLG's which will potentially cause glare. This could be remedied though with a diffusing output panel on the back of the MLG's. It should also be noted that the LCP's and LRB's are misrepresented by RADIANCE in terms of luminance. RADIANCE uses algorithms to simulate the light output distribution of these devices, it doesn't simulate the actual physical elements. Thus in reality these devices may potentially cause much more glare than is indicated by Table 2. The light shelf performed slightly better than the other redirecting devices in terms of the DGP.
Conclusion From the conducted simulations the most effective daylighting system for distributing light throughout the test room as well as providing some shading was the light shelf. The MLG's and light shelf were the two devices that were simulated as external elements to the window. Its no too surprising that these devices performed the most optimally as they were able to provide shading as well as redirect sunlight from high solar elevations in summer. The devices integrated into the window (LCP, LRB) struggled to redirect a significant amount of daylight during summer. All daylight redirecting devices are appropriate for sub-tropical conditions but there are many factors to consider before selecting a particular device. Simulations, the type that were conducted in this investigation are necessary to ascertain the benefit of using a particular daylighting strategy and also optimising that strategy to extract the maximum benefit. The goal of the simulations was not to optimise the performance of any particular device, but to use literature, known or inferred data for each device as it would be used in sub-tropical conditions for the George St test room case. The accuracy of RADIANCE relies heavily on accurate material and geometry descriptions of the various devices, thus any modification of any material or orientation of a device could drastically change its performance. Degradation of the materials is also an important factor not considered in the simulations with all devices considered to be at optimal performance. The analysis conducted here applies to multistorey medium to deep plan buildings in sub-tropical locations. The study has found that retro-fitting existing buildings with the daylighting technologies discussed in this paper has a positive yet at times limited effect on illumination quality. Using daylight redirecting devices will also save energy if used in conjunction with a well designed electric lighting system. However, they will also increase solar heat gain within buildings which can offset energy savings. Specifically, very few buildings in Australia employ any window daylight redirecting devices. This research provides little evidence of the value of retro-fitting existing buildings with the daylight redirecting devices considered here to improve lighting quality, even though this is achieved. There is greater cause for employing these window daylighting devices for a building designed from the ground up to include a tailored daylighting design to suit the occupants needs. References [1] Collins BL. In: Windows and people: a literature survey. Psychological reaction to environments with and without windows. NBS Buildings Science Series, Vol. 70. Washington, DC: NBS, 1975. [2] Heschong L, Mahone D, Kuttaiah K, Stone N, Chappell C, McHugh J, Burton J, Okura S, Wright R, Erwin B, Digert N, Baker K. Daylighting in schools: an investigation into the relationship between daylighting and human performance. Fair Oaks, CA: The Heschong Mahone Group, 1999. [3]
Charles, K. E., & Veitch, J. A. (2002). Environmental satisfaction in open-plan environments: Effects of workstation size, partition height and windows. Ottawa, Ontario: Institute for Research in Construction, National Research Council Canada. [4] Mark Rea, editor. IES Lighting Handbook, reference volume 15, page 517. Illuminating Engineering Society of North America, New York, 1993. [5] Ward G., Shakespeare R., 1998. “Rendering With RADIANCE. The Art and Science of Lighting Visualization,” Morgan Kaufmann Publishers [6] light
Greenup PJ, Edmonds IR. Test room measurements and computer simulations of the microguiding shade daylight redirecting device. Sol Energy 2004;76:99–109.
[7] Freewan AA. Maximizing the lightshelf performance by interaction between lightshelf geometries and a curved ceiling. Energy Convers Manage (2009), doi:10.1016/j.enconman.2009.09.037
[8] Nabil A, Mardaljevic J. 2006. Useful daylight illuminances: A replacement for daylight factors. Energy and Buildings 38(7): 905–913. [9]
Edmonds IR, Greenup PJ. Daylighting in the tropics. Sol Energy 2002;73:111–21.
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Thermo-accumulation: an effective alternative for increasing the power load factor in electricity retailing 1,2 1
Vieira, Francisco Anizio; Frota, 2Maurício Nogueira, and 2Souza, Reinaldo Castro
Asea Brown Boveri, ABB Postgraduate Metrology Programme Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil 2
Abstract In Brazil, the commercial building sector is one of the fastest growing energy consumers in the country, accounting for 14% of the total demand. This is a market niche that has a great potential for the use of ‘cool storage’. Studies have shown that thermo-accumulation is an attractive technology to increase the electric power load factor which can lower tariff billings in the electricity retailing. The aim of this work is to validate the technological benefits of thermo-accumulation applied to the electrical sector as an economically feasible alternative for power load displacement at peak mode. In addition, it presents results of a literature survey on tariff billings and regulatory aspects of the electrical sector, discusses the aerial and underground distribution systems at locations of high power load demand and develops a technical analysis of power substations. In a recent tariff billing revision —where the electrical sector shared energy-efficient gains with consumers—, the study suggests alternate tariff schemes and power load displacement policies. Three major results were found: (i) the feasibility of thermo-accumulation in acclimatization; (ii) the reduction of operational cost of electricity for commercial air-conditioning users and (iii) a proposal for differentiated retailing tariff billings. Advantages in the use of thermo-accumulation technology by electricity companies are unequivocal: on the one hand it provides better tariff schemes for consumers and, on the other hand, it is environmentally friendly.
1. Introduction Energy is an essential ingredient in modern industrial societies. Transport, manufacturing, communication, trade and food preservation, to mention a few, depend on energy availability. But finiteness and exhaustibility of resources make the notion of indefinite energy availability problematic. With the emergence of the idea of sustainable development environmental and economic pressures (competitiveness and continuous quality improvement) are tightening up on the generation and rational use of energy. The pursuit of economic prosperity, environmental quality and social equity, the three dimensions of sustainable development, inspired the third generation of ISO standards. The ISO 50001 (Energy Management System) [1] is a typical example. It is able to provide organizations and companies with technical and management strategies to increase energy efficiency, reduce costs, and improve environmental performance. Data from the National Energy Balance 2008 (BEN 2008) [2] show that the energy consumption follows the pattern of the country’s economic growth. To meet the demand for electricity, the Ten Year Plan for Expansion of Power (PEP 2006/2015) [3] estimates that Brazil needs to increase its generation capacity to overcome a possible deficit in the near future. Electricity demand grows at a higher rate than the country’s ability to expand the national grid: the total primary energy supply grew 5.0% in 2007 (compared to 2006), while electricity consumption alone increased 5.7% over the same period [2, 4]. Power management plays an important role in the planning of the electrical sector as costs associated with overall planning and optimization of the national grid are significantly lower than those needed for expansion. Heating, Ventilating and Air Conditioning (HVAC) systems (the technology of indoor environmental comfort), which account for a large fraction of the consumption of electricity, are potential applications for thermo-accumulation —a process of accumulation of thermal energy in the form of sensible or latent heat. The thermo-accumulation is capable of keeping thermal energy for a long period of time without appreciable heat loss. A very favourable technique that enables more efficient and rational use of air conditioning systems as it generates cold throughout the night, stores it and uses it to cool the environment during the day when the electricity are much higher.
The aim of thermo-accumulation is to rationalize energy use by shifting electricity demand from high to low periods of utilization rather than to provide an energy-saving device. Thermo-accumulation can add value to the entire chain of the electrical sector to all parties involved: the environment, investor, licensee, consumer and society. The creation of new alternatives, pricing, technology, or related processes and regulations, among others, are cited as key measures for a new scenario, which includes the use of thermo-accumulation. An adequate application of a thermo-accumulation device to support a central air-conditioning system for large and medium-size consumers of electricity can reduce the demand values requested from the electrical system during peak periods. This would certainly generate savings for consumers and would mitigate investments needed to expand the insufficient system in place to meet higher demands. Thermo-accumulation finds natural applications in market segments exhibiting a clear periodicity in the demand such as: shopping centres, hotels, convention centres, commercial buildings, government agencies, hospitals, educational institutions, supermarkets and hypermarkets, shops, airports.
2. Scope of the work The aim of this work is to promote the use of thermo-accumulation as an strategy to: (i) shift loads enabling the proposition of a differentiated tariff; (ii) shift electrical loads during peak periods; innovation of the sector, notably pushing price-innovation (iii) generate opportunities for industries interested in benefitting from the use of thermo-accumulation during peak hours and (iv) create business opportunities for the use of a more homogeneous system of underground power distribution in downtown Rio de Janeiro18. 2.1 Pricing power Until 1981, electricity companies applied the single tariff system (Conventional Rate). Consumers were not concerned how the electricity was being consumed. The reason was clear: as there was no differentiation of prices in the electricity bills, consumers were not worried whether to consume more or less during the day or during the night. Let alone during the year. Depending on the availability of water, typical behaviour of the load throughout the day and throughout the year led to a tariff structure —Rates Blue and Green— which include the systematic application of the tiered rates according to the times of day (peak and off-peak) and periods of the year (dry and wet). The Blue Rate was conceived in 1982 and the Green Rate in 1988. This differentiated tariff introduces a more rational use of energy in the market, more consistent with potentials of the existing interconnected production and distribution power system installed [5]. 2.2 The underground electrical network The underground electrical network has some special characteristics: high marginal cost for expansion; large concentration of demand; high reliability and a great number of commercial consumers. In Brazil, the overwhelming majority of underground power distribution is located in the cities of Rio de Janeiro, São Paulo, Brasília, Belo Horizonte and Curitiba. The largest in Latin America, Rio de Janeiro’ underground electrical network has about 3,400 underground chambers. The underground electrical network of downtown Rio de Janeiro is unique: the commercial sector accounts for most of the demand during business hours (usually from Mondays to Fridays, between 8 am to 8 pm) with no significant load during weekends. The commercial sector is a great consumer of energy: about 86% from electricity and 14% from other sources. [2]
3. Thermo-accumulation: an alternative technique to rationalize the use of electricity Thermo-accumulation can be used as a strategy to rationalize the use of electricity by shifting loads during periods of increased consumption. It plays an important role for the electrical sector; particularly 18
www.light.com.br
in terms of opportunities to implement differentiated tariffs while promoting trade. It denotes a technical and economical alternative to "generate and storage cold" allowing air conditioning systems to operate more efficiently. This becomes possible by levelling the thermal load between periods of high and low demand. As a great solution, its use benefits the entire chain of the electricity system (generation, transmission, distribution) by shifting demand for electricity from "peak time" to "off-peak hours". 3.1 Advantages and limitations of thermo-accumulation Among the main advantages introduced by thermo-accumulation technique has several advantages [6-8]: (i) reduction of the capacity (and physical size) of the refrigeration system (e.g.: refrigeration compressors, water pumps, cooling towers) that reflects on the investment cost of the cooling unit; (ii) reduction of installed power system cooling, which results in a lower demand for energy; (iii) reduction of the electrical infrastructure and plumbing; (iv) increase in reliability of the refrigeration system due to "cold reservoir"; (v) shifting load to off-peak hours of the electrical system; (vi) introduction of a differentiated tariff to reduce the cost of electricity; (vii) better use of energy during the 24-hour daily operation; (viii) increase of the load factor of the system “producing cold” and increase in equipment efficiency, bringing the work closer to the ideal operating conditions. And limitations too: (i) the need of additional cooling systems for the installation of storage tanks; (ii) increase in the initial investment required to implement a conventional cooling system; and (iii) reduction of the uncertainty associated with measurements demanded by the thermal load. Thermal systems are classified based on the nature of the working fluid used. The elements commonly utilized in systems designed for thermal comfort are: (i) water (pure substance) in its liquid phase (ii) water in its solid phase (ice) and (iii) saline solutions [9-11]. 3.2 Alternatives to the use of thermo-accumulation Figure 1 illustrates the benefits introduced by thermo-accumulation in the operation of a classic refrigeration system. A central cooling system of the conventional type denotes the thermal load. It shows the profile of the heat load of an existing commercial facility whose maximum load (1350 TR) is attained at 2 pm. Figure 1: Conventional cooling system (without thermo-accumulation).
Figure 2 below compares a central refrigeration system with and without thermo-accumulation. As can be seen, the maximum installed power is reduced from 1350 to 750 TR (a 37% reduction) when thermo-accumulation is introduced. In addition, thermo-accumulation allows operation at maximum power (maximum efficiency) and shutdown at peak hours (from 5 to 8 pm). The area shown in blue denotes the energy generated by the chiller and heater. The area shown in red refers to the energy generated by the chiller to supply the load. The area in green represents the energy stored to supplement the power generated by the chiller required to meet the load.
Figure 2: Profile of the heat load with thermo-accumulation
As shown in Figure 3, the use of thermo-accumulation provided a substantial reduction of the nominal capacity of the chillers to 750 TR, tons of refrigeration (37% reduction of the nominal capacity when compared to the conventional cooling system operating at 1350 TR). Thus, without reducing the level of thermal comfort of the facility, it is possible to stabilize their energy consumption curve. Figure 3: Profile of the heat load with and without thermo-accumulation. Source: Modified from Guzman [12].
The implementation of a system of thermo-accumulation is simple from the technical point of view, not requiring major changes in the basic thermo-fluid circuitry. 3.3 Thermo-accumulation: proposition of a electric utility bill model In light of the conditions prevailing in the market of electricity energy in Brazil, this work contributes to the formulation of an alternative electric utility bill model. The proposition is based on the use of thermo-accumulation systems as a strategy for rationalization of energy generated by displacing load during hours of maximum demand. The proposed business model analyzed refers to a system of
underground power distribution. The analysis is justified by the fact that there is already a large concentration of business consumers that have access to underground systems. Thermoaccumulation becomes an attractive alternative for commercial installations whose electricity demand exceeds 50% at peak-hours to power their refrigeration systems. The (Brazilian) National Grid (BNG) has to deal with different levels of load -ranging from 60% to 70% (light period), 70% to 90% (average) and 90% to 100% (heavy period)-, all referenced to the maximum capacity of the system. Peak loads observed by BNG occur between 5 and 10 pm (shown in figure 4) across the country, while in the underground electrical network in downtown Rio de Janeiro between 10 am and 3 pm (shown in figure 5). Furthermore, the different levels of load of the underground electrical network can be compared to those of BNG: it is 15% to 20% (light period), 70% to 100% (average) and 20% to 30% (heavy period), respectively. Hence, it is underused from 8 to 12 pm and from 0 to 7 am. The low use of the network during the night and at dawn compensates for the use during the day. Figure 4: Typical load curve of BNG. Source: Brazilian Electric Sector Operate (ONS)19.
Figure 5: Typical load curve for the underground electrical network. Source: Brazilian Electricity Regulatory Agency (ANEEL20).
19 20
www.ons.org.br www.aneel.gov.br
The following is a typical daily load for client type low tension - underground electrical network (fig. 6). Figure 6: Curve of load feature to client type underground electrical network. Source: ANEEL [13].
The longest period of loading the profile of Figure 6 occurs between 8 am and 6 pm. During the peak period from 6 to 8 pm, the electrical network is charging low, (from 10% to 35% of maximum load), while from 9 pm to 6 am it continues with charging less than 10% of maximum capacity. 3.4 Innovation of the electrical sector The competitiveness of economic agents can be defined in several ways. Giovanni Dosi [14] stresses two major approaches: the structure of industries and technological evolution. The evolutionary approach is of vital importance by its concepts of selective environment, technological trajectory and technological paradigm, and contributes to expedite the analysis of the structure of the electricity market. Electricity companies should remember that the thermo-accumulation can also be used with natural gas -an environmentally friendly fossil fuel. The customer who buys a system with an investment of this size does not change the energy input in the short term. The tendency is to stay with the technology by the lifetime of the machine, which is around 15 to 20 years. The refrigeration industry has the opportunity to influence the electricity market by indicating environmentally friendly and energy-efficient models and better standards for cooling systems. And vice-versa, electricity suppliers ought to participate in the debate of energy-efficient devices and monitor the refrigeration market. As a rule, consumers remain foreign to technical, regulatory and pricing issues but they always require reduction in tariffs. It is therefore left to the refrigeration and electricity suppliers communities to allow for the implementation of feasible and attractive technological schemes (such as the thermo-accumulation) to cut down costs. Refrigeration units now installed in Rio de Janeiro are adapted to new requirements of the refrigeration market (Montreal protocol). The introduction of new tariffs may encourage changes in attitudes and promote new concepts of commercial refrigeration to replace the existing ones. 3.5 Flexible rates In market economies, excess demand is removed by price increase. In regulated markets, electric utility bills can not enjoy the flexibility of special rates. In this case, there would be only one option to eliminate excess demand: rationing. Turvey and Anderson [15] describe and justify situations where an adequate increase in tariffs becomes an effective way to deal with increased demand. They also showed that an underestimation of the predicted growth in demand led to wrong decisions on the expansion of power capacity when time is a crucial variable to allow an appropriate solution. They also mentioned that significant changes in climatic conditions may jeopardize the ability to meet the electricity demand in countries where energy matrices are based on hydroelectricity.
Prices play a key role in determining the demand for energy. Thus, the tariff policy may:(i) postpone investments in expansion of infrastructure in the electricity sector, (ii) rationalize energy use and (iii) change the schedule of the use of electricity by consumers among other possibilities. It is vital to have a combination of new tariffs and existing technologies. As such, they could modify patterns of electricity consumption in use for a long time. The current measurement systems for consumers hourseasonal (Rates Blue and green) and Fare Conventional allow the most dynamic forms of sale of electricity. They depend only on new charges that are able to encourage new patterns of use. 3.6 Pre-fixed rate model A major hurdle to the widespread use of thermo-accumulation is the price of energy. It does not encourage consumers to use it during light periods (late night and at dawn). Consumers of the underground electrical network, which have cooling systems that operate on a 24 hour basis, or extend their operation for peak hours, are encouraged to implement thermo-accumulators. But that is not enough, because the vast majority of consumers do not operate on a 24 h basis, as shown in Figure 6. For the change in consumer behaviour is mirrored in the load curve of the electrical network, it is necessary to stimulate consumers through incentives. The offer of a more attractive rate is one mechanism that produces results. Following this line, we propose a strategy based on three pillars: §
§
§
keep the tariff at the tip position: 3 (three) consecutive hours defined in terms of the schedule of higher loading of the electric supplier. This will help maintain the current tariff structure policy if there is no distortion by the consumer of the importance to the electrical system there are reductions in energy use during this period. Keep the current cost of the peak tariff; reduce the stand off-peak tariff: from 21 (twenty one) to twelve (12) hours included in the time interval of the stand off-peak tariff (e.g.: from 7 am to 6 pm and from 9 to 10 pm). Keep the current cost of off-peak rate; and create job special tariff (ST): 9 (nine) hours included in the time interval of the current stand off-peak tariff (e.g.: late night and at dawn, i.e., from 10 to 12 pm and from 0 to 7 am, applying price tariff below the price of the tariff applied to off-peak).
Figure 7 shows the same curve in Figure 6, with indications of the three periods here proposed. Figure 7: A proposal for three billing periods.
The electricity tariff structure obeys the complex methodology developed by the Brazilian Electricity Regulatory Agency (Aneel). Thus values to be charged shall be constructed in accordance with Aneel to the three periods suggested here. To strike a balance between the increase in consumption during the night and a tariff reduction, one may offer to:
• •
consumers a substantial reduction in rates for the electricity consumed to justify investments in thermo-accumulation technology; the electric utility and the whole chain of the electrical sector, which benefit from the possibility to postpone investments to expand the infrastructure to expand operations.
3.7 A would-be electricity tariff structure for underground electrical network Although the data presented here reflect actual data collected from a utility power supplier, the supplier’s name was omitted to preserve confidentiality. And only consolidated data will be presented. For the sake of analysis, load patterns of aerial and underground sub-stations are classified as follows: § Group 1 (SE1, SE2 and SE3) - underground sub-stations located in areas with high charge density (essentially commercial consumers); § Group 2 (SE4, SE5 and SE6) - underground sub-stations located in areas with high density of charge (commercial and residential consumers); and § Group 3 (SE7) - air substation located in an area with an average charge density (commercial, residential and industrial consumers).
3.7.1 Analysis of load patterns from 7 am to 6pm Figure 8 presents data of load patterns from 7am to 6 pm for the three groups above over a week’s period of observation. From Monday to Friday their load patterns nearly coincide. Loads vary between 70% and 90% of the planned capacity for the system. At weekends, the three groups display a fall with respect to the other days of the week. However, for group 1, the drop is substantial. Saturdays operates with loads ranging from 23% to 31%, and on Sundays from 13% to 23%. This confirms the predominance of commercial loads operated by the underground electrical network. On Saturdays, groups 2 and 3, operate with loads ranging from 58% to 65% and, on Sundays, from 46% to 56% of full capacity. Figure 8: Typical daily load curve for sub-station SE (from 7am to 6pm).
3.7.2 Analysis of load patterns from 6 to 9 pm Figure 9 shows loads for the three groups analyzed in the period from 6 to 9 pm during the week. There is no convergence for the three groups from Mondays to Fridays, and only for groups 2 and 3. In group 1, loads vary between 42% and 56% of the capacity planned for the system. In groups 2 and 3, they vary from 66% to 84%. At weekends, the three groups display a fall in loads patterns compared to the other days of the week. However, for group 1 the decrease is substantial. Saturdays operates with loads ranging from 16% to
25% and from 12% to 22% on Sundays. This confirms a peculiarity of the underground electrical network, with a predominance of commercial cargo. For groups 2 and 3, on Saturdays, they operate with loads ranging from 57% to 72% and 51% to 66% on Sundays.
Figure 9: Typical Daily Load patterns for SE( from 6 to 9 pm).
3.7.3 Analysis of load patterns from 9 to 12 pm and 0 to 7 am Figure 10 shows the loads for the three groups analyzed for the periods from 9 to 12 pm and from 0 to 7 am on weekdays. Again, there is no convergence for the three groups in the Monday-Friday period, and only for groups 2 and 3. In group 1, the loads vary from 17% to 26% of the capacity planned for the system. In groups 2 and 3, they vary from 46% to 64%. At weekends the three groups display a decline with respect with the other days of the week. Group 1 keeps loads very low when compared to the other two. On Saturdays, group 1 operates with loading that varies from 14% to 21% of the planned capacity, and on Sundays, from 12% to 20%. This is a particularity -the predominance of commercial loads- of the underground electrical work. On Saturdays, groups 2 and 3, operate with loads that vary from 46% to 61%, and on Sundays, from 45% to 58%. Figure 10: Typical daily load patterns for SE( from 9 to 12 pm and from 0 to 7 am).
3.8 Value of the displaced load The opportunity cost to shift from peak load to a lower demand schedule (as illustrated in Figure 11), which can be done by means of thermo-accumulation, is highly lucrative for electricity companies. This allows electricity suppliers to meet new consumers’ demand with the same existing infrastructure.
Figure 11: Load transfers during the day and at night.
3.9 Formulation of rates: competitive advantages of electricity suppliers The strategic vision of electricity utilities should go beyond the conventional standards set and backed by the electrical sector. The adoption of new designs to replace the old conservative practice ought to be considered. Innovation is made necessary to explore alternatives already available but not explored in full to promote efficient use of electricity, in particular to encourage less consumption during the peak period of the power system. Santos [16-18] stresses that the tariff issue can not be treated simply as a static system of cost allocation between consumers in distribution systems. It needs to be considered as a dynamic system, which leads to different reactions in the load curve in accordance with the price signal to which consumers are subjected. Discounts to be applied to a new tariff will be calculated in several ways. One of the following alternatives should be considered: (i) rebates for existing taxes or to the existing burden; (ii) alternative methodologies for calculating the three tariff periods; (iii) new methodology to calculate tariffs in three periods, including an analysis specific to the underground system; (iv) temporary price reductions, seeking financial returns for consumers to invest in projects of thermo-accumulation and (v) tariff reductions in the sale of electricity (“take or pay" or "ship or pay") to reach minimum load factor for consumers. Detailed information on the use of thermo-accumulation as a strategy for load shifting is available elsewhere [19]. A new tariff does not depend on any particular measuring technology to be computed and formalized in the electricity bill. Electricity meters and programs used by them incorporate functions that enable electricity metering based on a new rate applicable to a third period of special tariff (ST). These meters are able to measure energy and demand functions in accordance with a scheduled time in four periods.
4. Conclusions Retail electricity market may contribute to sustainable development by adopting environmentally friendly and socially responsible technologies to create fairness for power consumers while achieving the revenue requirements of electricity utilities. A new electricity tariff structure can be achieved by load management. To directly control or indirectly modify the patterns of electricity use of various consumers of a utility, peak loads need shifting. This is can done by means of thermal systems such as the thermo-accumulation. The adoption of thermo-accumulation technology can provide: § § §
modernization of consumers’ obsolete refrigeration systems (still equipped with Montreal protocol banned CFC working fluids) by introducing ozone friendly refrigeration technologies; gains for new entrepreneurs, universities, laboratories, researchers, manufacturers in an emerging alternative market and proposals on electricity tariff restructuring to promote efficient power generation and utilization.
5. References [1]
ISO/CD 50001 - Energy management systems - was prepared by Project Committee ISO/PC 242, Energy management - document distributed for review and comment. Version 2.1c2 Date: 2009/6/17 25 W 43rd St, New York, NY 10036 Email
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SATEIKIS, I. Determination of the amount of thermal energy in the tanks of buildings heating systems. Energy and Buildings, 2002.
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ELECTRIC POWER RESEARCH INSTITUTE. Water-thermal energy storage: Using off-peak energy for low-cost space conditioning. Electric Power Research Institute, 1992.
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VAN WYLEN, GORDON JOHN. Fundamentals of Classicla Thermodynamics. Edgard Blucher, São Paulo, 1990. 2da Ed 565p.
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DOSSAT, R. J. Princípios de Refrigeração. McGraw-Hill, São Paulo, 1992.
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GUZMÁN, J. J. M. Estudo Experimental do Super-resfriamento da Água em Cápsulas Cilíndricas. Doctor Thesis, 2004. Can be downloaded at: www.puc-rio.br.
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ANEEL. Nota técnica no 0228/2008. Can be downloaded at: www.aneel.gov.br
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DOSI, G. Expected energy use of ice storage and cold air distribution systems in large commercial buildings. Electric Power Research Institute, 11, 1990.
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SANTOS STEELE, P. E. Tarifação dos serviços primários de distribuição - mestrado em engenharia elétrica. Dissertação de Mestrado, Universidade Federal de Itajubá, 1999. Can be downloaded at: www.unifei.edu.br.
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Rate structures for consumers with onsite generation: Practice and innovation. National Renewable Energy Laboratory, 2006.
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Vieira, F.A., Thermo-accumulation: an effective alternative for increasing the power load factor in electricity retailing leading to differentiated tariff billings. Master Thesis. Post-graduate Metrology Programme (Metrology for Quality and Innovation). Catholic University of Rio de Janeiro. Brazil. May 2009.
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Elevators and escalators: Energy performance and Strategies to promote energy efficiency Anibal de Almeida1, Elisabeth Dütschke2, Carlos Patrao1, Simon Hirzel2, João Fong1 1ISR-University of Coimbra, Portugal 2Fraunhofer ISI, Karlsruhe, Germany
Keywords Elevator, Lifts, Escalators, Energy efficiency, Standby energy consumption, Barriers, Monitoring, Strategies
Abstract Elevators and escalators are the crucial element to make it practical and comfortable to live, work and shop several floors above and below ground. In tertiary sector of the EU-27, about 1.6 million elevators are installed as well as about 56,000 escalators and moving walks. Their energy consumption adds up to 3 to 8 % of the overall electricity consumption of the building. However, elevators and escalators have not received much attention in terms of energy efficiency for a long time. In this paper, we characterize the energy consumption profiles these vertical transportation devices in standby and running based on a monitoring campaign conducted within the E4-project. An estimation of the overall energy consumed by elevators and escalators is presented. Building on this, potentials for saving energy are identified – both from a technical point of view as well as from a behavioral approach. The technical analyses show that the savings potential is up to 66 %. The behavioral approach includes an interview study and identifies market barriers to the penetration of energy efficient technology and proposes strategies to overcome those barriers.
Introduction Vertical transportation systems, for both people and goods, have been employed by mankind since ancient times. In early agricultural societies, these devices relied on men, animals or water power to lift the load. The Industrial Revolution brought with it a number of technological advancements. Machine power allowed for fast developments, and safety systems were introduced. In 1880 the first electric motor was used to power an elevator. Today, in the European Union 27 (EU-27), more than 4.8 million elevators and 75.000 escalators and moving walks are operating. Every year 125.000 new elevators and 5.000 new escalators and moving walks are installed (extrapolation of ELA-Elevator market statistics 2005-[1]). About 1.6 million, i.e. one third, of these elevators are installed in the tertiary sector and about 56,000 escalators and moving walks, i.e. 75 %. Their energy consumption is estimated to add up to 3 to 8 % of the overall electricity consumption of the building [2/3]. Installations have a long life-cycle [2], thus technological innovations need a lot of time for diffusion. Therefore, it is very important to characterize people conveyors (elevators and escalators) in terms of electricity consumption and technology in the tertiary sector in the EU as well as to promote the efficient use of electricity in these applications through the application of cost-effective energy efficient technologies available or emerging in the market. However, elevators and escalators have not received much attention in terms of energy efficiency for a long time. Results of the E4-project which form the basis for this paper estimate the savings potentials of energy efficient technology up to 55 to 66% for elevators and to 28% for escalators thus holding a significant potential waiting for realization [4]. •
Presently elevators and escalators represent 1% of the total electricity consumption in the tertiary sector (
Figure 35), with a trend for a significant increase of this share.
Figure 35: Electricity consumption shares in tertiary sector in the EU (source [5])
0% 0% 1% 3% 3% 3% 4% 25%
5% 6% 9%
16% 11% 14%
Heat pumps Laundry (in hotels, health) Elevators ICT office Cooking (in hotels, health) Circulation pumps and other heating auxiliaries ICT data centers Lighting street Electric heating Refrigeration Ventilation and air-conditioning Hot water Misc. building technologies Lighting
In the remainder of this paper, we first provide further information about the energy consumption of elevators and escalators in the tertiary sector. As part of the E4-project, a monitoring campaign has been carried out which included the measurement of 81 installations. From this campaign a summary of the monitoring data, including the characterization of standby consumption, will be presented. Then the potentials for energy efficiency are identified by estimating potential savings under the condition of using the best technology available on the market. This section also includes an overall estimation of the energy consumption of elevators and escalators in the tertiary sector. The following chapter is devoted to identifying barriers that might hinder the realization of this potential. Following this, strategies are proposed to overcome those barriers.
Energy consumption of elevators and escalators in the tertiary sector Monitoring campaigns were carried out within the E4 project as a contribution to improve the understanding of the energy consumption and energy efficiency of elevators and escalators in Europe. The aim of these monitoring campaigns was to broaden the empirical base on the energy consumption of elevators and escalators, to provide publicly available monitoring data, and to find indications for system configurations using little energy. An effort was made to select lifts for this study from different years of installation and using different technologies in order to be able to compare the performance of a wide range of lifts with different characteristics. Originally, 50 installations were planned to be monitored within the project. In the end, 74 elevators and 7 escalators, i.e. a total of 81 installations, were analyzed in the four countries under study: Portugal, Poland, Italy and Germany. Figure 36 shows the monitored elevators by sector and country. Figure 36: Monitored elevators by sector and country
40 35 30 25
Portugal Poland Italy Germany
20 15 10 5 0
Residential buildings Tertiary buildings
Industrial buildings
A common methodology was used by all partners to ensure the repeatability of the measurements. The methodology considers energy measurement relating to the normal operation of the elevator, escalator and moving walk including: • Main energy - elevating/escalating/moving walk equipment such as: motor, frequency converter, controls, break and door. • Ancillary energy - car auxiliary equipment such as: light, fan, alarm system, etc. The reference measurement cycle for elevators, starting at the bottom landing, consists of: 1. Opening the Door 2. Closing the Door 3. Driving the car from the bottom landing to the top landing 4. Opening the Door 5. Closing the Door 6. Driving the car from top landing to the bottom landing Figure 37 shows the annual energy demand for each of the audited elevators. Figure 37 : Total annual energy consumption of the elevators audited
It is clear that there are large differences between the energy consumption of the different elevators analyzed. Even if this consumption is compared with elevators of the same rise height, same velocity or same nominal load, the conclusions are not clear about what technology is more efficient as there are a lot more factors to be included in the analyses, such as lighting or type of control. Amongst others, the technologies used in cabin lighting and control equipment can explain these differences between the analyzed elevators. The measured standby power also varies widely. This standby consumption is due to the control systems, lighting, floor displays and operating consoles in each floor and inside the elevator cabin. In the analyzed elevators the standby power ranges from 15 W to 710 W. Figure 38 shows the standby consumption and the running mode consumption, in proportion to the overall consumption of the elevators audited. Standby consumption varies from 5% to 95%. These differences originate especially from different usage patterns (the higher the number of trips, the higher in tendency the running consumption) on the one hand, and from the different consumption values during running and standby on the other.
Figure 38: Total annual energy demand of the elevators audited
Figure 4. Share of running and standby consumption. According to European Lift Association (ELA) statistics there are 75.000 escalators and moving walks installed in the EU-27. Based on the surveys conducted during the E4 project, two assumptions can be made: • 75% of the escalators are installed in commercial buildings, the remaining 25% being in public transportation facilities. • 30% are equipped with a Variable Speed Drive (VSD) Escalators and moving walks are estimate to consume around 900 GWh of electricity each year [4].
Estimation of savings potentials for elevators and escalators The characterization of the installed elevator stock according to building type and basic characteristics was made, by means of a survey conducted in cooperation with the national member associations of the ELA. Detailed data was collected in 19 European countries. An overview of the extrapolated stock numbers for the EU 27 is given in Table 15. Table 15: Elevators in the EU27 by drive technology (units) Hydraulic Geared Gearless Traction Traction Residential 743.979 2.254.112 100.330 Tertiary 333.248 946.208 270.344 Industrial 49.312 126.397 227 Total 1.126.539 3.326.718 370.901
Total 3.098.421 1.549.801 175.936 4.824.157
Typical values for the electricity consumption of elevators are based on the monitoring campaign carried out during this project and briefly described above. With respect to the achieved values of potential savings, it is important to note that: • The initial cost of the technologies used, while being an important issue regarding their application, has been not considered; therefore, no indications are provided about costeffectiveness of using those technologies; • Maintenance costs such as labor and spare-parts, have not been included in the calculations, even if some of the electronic components in inverters (e.g. cooling fans, capacitors, internal relays) ought to be periodically serviced in order to avoid degradation in inverter’s performance;
•
Some technologies may increase standby consumption while reducing consumption during the running phase. Therefore, their application should be carefully evaluated on a specificcase basis.
The total electricity consumed by elevators is estimated at 18,4 TWh, of which 6,7 TWh are in the residential sector, 10,9 TWh in the tertiary sector and only 810 GWh in the industrial sector. Figure 39 shows the running and standby estimated annual energy consumption of European elevators in the residential and tertiary sector. Although there is a smaller number of elevators installed in the tertiary sector their energy consumption is far greater than in the residential sector due to their more intensive use. Figure 39: Elevator annual electricity consumption [4]
As it can be seen, the standby electricity consumption represents an important share of the overall electricity consumption, especially in elevators installed in the residential sector where the time spent in standby mode is larger. Figure 40 presents the standby and the running mode, in proportion to the overall energy consumption of elevators in the residential and the tertiary sectors. Figure 40: Proportion of standby and running mode to overall energy demand of elevators [4]
The estimation of the potential savings in elevators is made by assuming that the Best Available Technologies (BAT) are used along with two different scenarios for the standby mode. For the running mode consumption the following assumptions were made: • • •
Motor efficiency: 15% lower losses than IE3 in IEC60034-30 (Super Premium or Permanent Magnet Synchronous Motors) [6] Efficiency of helical gear – 96% Friction losses (5%)
•
Efficiency of VSD (95%) [7]
For the standby mode consumption two scenarios were considered: 1. Consider the best available technologies for each of the components which contribute to the standby energy consumption: • LED Lighting (varies from 12W for lift with load 320 kg to 18W for 1000 kg load lift) • Electronic Controllers (25 W) • Inverter (20 W) 2. Additionally consider that all non-essential components which contribute to the standby energy consumption when the elevator is not in use are turned off and that the controller and inverter are put into sleep-mode (1 W each). Figure 41 and Figure 42 show the estimated electricity consumption, in the residential and tertiary sectors, according to the different scenarios proposed. Figure 41: Estimation of the electricity consumption of elevators according to different scenarios in the residential sector [4]
Figure 42: Estimation of the electricity consumption of elevators according to different scenarios in the Tertiary sector [4]
The results show that overall savings of more than 65% are possible. A reduction of 10 TWh is achieved in the 1st scenario and of 12 TWh in the 2nd scenario which translate into a reduction of around 4,4 Mtons of CO2eq and 5,2 Mtons of CO2eq, respectively21, with the current electricity production methods. 21
[ ] For converting the electricity into CO2 eq. we used the carbon emission factor used by the EuP EcoReport tool
Savings in the standby energy consumption are particularly noticeable even in Scenario 1 where although low power equipment is used it is always kept on even when not in use, as is presently the common practice. A reduction in standby power of over 80 % is considered feasible with off-the-shelve technologies. In particular, the use of LED lighting can play a major role in this reduction. For the estimation of potential energy savings in escalators and moving walks it is considered that all of the units installed would be equipped with VSD. Furthermore, it is considered that when stopped the controller and inverter only consume one Watt each. A potential reduction in the electricity consumption of around 28 % (approximately 250 GWh pa) would be possible translating into a reduction in CO2eq emissions of 100.000 ton per year.
Barriers to energy efficiency As outlined above, significant and extensive savings of energy would be possible for elevators and escalators without decreasing comfort or accessibility if the best available technologies were applied. However, this is not the case in reality. On the one hand, due to the long-life-cycles of elevators and escalators a long period of time is needed until these technologies will have replaced existing stock; however, also for new installations, customers do not always choose the most efficient technology. Thus, this section aims at identifying reasons that prevent these technologies from conquering the market as soon as possible. Reasons hindering the diffusion of energy efficient technologies are usually termed as barriers. A barrier is defined as a mechanism that inhibits a decision or behavior that appears to be both energy efficient and economically efficient; in particular, barriers are claimed to prevent investment in costeffective energy efficient technologies [8, p. 27]. Methodology In addition to identifying common barriers from the literature 23 expert interviews – either written or oral – were conducted as a first step. In a second step, results from the interviews were discussed with the E4 project team as well as ELA-members, thus validating the information obtained as well as the conclusions drawn. Experts are usually defined as individuals who have special knowledge or experience of a topic of interest. For the purpose of this study, a list of potential stakeholders was produced a starting point to identify relevant experts. Five categories of stakeholder resulted (cp. Table 16:). Table 16: Categories of stakeholders identified and number of interview participants Stakeholder categories Manufacturers, installers, service & maintenance Architects, construction engineers, lift consultants Construction companies Building administrators and operators Notified bodies
Number of interviews 11 8 1 1 2
The experts surveyed represented several European countries, e.g. Germany, Switzerland, Italy, Portugal and Poland. An interview guideline was provided beforehand based on an analysis of the literature on barriers and on the elevator and escalator market. The guideline consisted of several parts including a general assessment of the elevator and escalator market regarding energy efficiency, a list of potential barriers as well as strategies and tools for market transformation.
which the official life cycle analysis tool used developed in the context of the EuP Directive 32/2005/EC (0.4582 kg CO2 eq. /kWh).
Results and conclusions on barriers The main conclusions to be drawn from our study on barriers can be summarized as follows: Major barriers to the penetration of energy efficient technologies arise from a lack of monitoring energy consumption of installations and from a lack of awareness as well as a lack of knowledge about energy efficient technology. In general, it is not common that operators of elevators or escalators regularly monitor the energy consumption of their equipment. In most cases, no technical appliances are installed that would allow for regular monitoring of installed equipment; thus the energy consumption of elevators and escalators cannot be separated from other equipment, e.g. lighting, automatic doors. This is seen as related to the fact that individuals choosing equipment as well as operators and users are not aware of the energy consumption of the equipment: Due to a low degree of awareness no measurement devices are installed – due to missing data individuals do not become aware for potentials to increase energy efficiency of existing installations or to think of this issue in case new installations. Information on energy efficient technology is not judged as something that is difficult to obtain by the experts surveyed. However, the main sources for information that are regularly used in case of new installations as well as in case of retrofitting are the manufacturers and their sales representatives. Neutral sources for information are missing or hardly known. The experts emphasized that the knowledge provided by sales representatives is usually restricted to the technology used by their company and that energy efficient technology is sometimes too new to be fully understood even by company representatives. Clients themselves usually have little knowledge on this topic and are thus not able to ask for relevant data. Thus, installations and components are usually chosen without a (comprehensive) assessment of their energy consumption and without considering life-cycle approaches. In addition to this, an installation is often neither chosen by the later operator/user of an installation nor the one paying for the energy consumption – who may be but not always is identical to the operator/user. Thus, a split incentive problem occurs: Buildings including an elevator or escalator are often erected by a general contractor for whom the energy consumption of the lift or escalator installed does not matter at all. Thus, life-cycle costs play a minor role when an installation is chosen. This may also be the case for retrofits or refurbishments of installations: Retrofits are often initiated by the operator/administrator of an installation – who does not necessarily benefit from optimizing energy costs of an installation. The split incentive problem is worsened due to low levels of awareness for this issue on the side of operators/administrators/users. It is further intensified as maintenance and energy costs are often divided between several occupants of a building which lowers the probability that they will provoke attention. Other barriers, e.g. lack of time or capital, reliability of technology, legislation, only play minor roles. However, price is crucial although lack of capital is not a major problem. This has to be seen in relation to the split incentive problem already addressed. Moreover, economic efficiency of energy efficient technology is a topic that is highly debated and which suffers from a lack of reliable data. Few examples of technical measures were given during the interviews and the group discussions for which economic pay-off is not doubted. The best example for a unanimously accepted measure is turning off the light when the car of the elevator is not in use and equipping the car with energy efficient lighting. As outlined above, this measure would already strongly contribute to decrease the energy consumption of elevators. However, due to the other barriers – lack of information and awareness as well as split incentives – it is often not realized. For other measures, e.g. investing into the drive system, opinions on economic efficiency were diverse and heterogeneous – even across experts from manufacturing and notified bodies. For example, experts stated wide ranges for prices for certain measures, e.g. regeneration, which, of course, lead to differing opinions regarding economic efficiency. In general, some experts pointed to the long life-cycles of installations which offer a long range for investments to become efficient. Moreover, economic efficiency was perceived to be more easily realized for large scale installation than for small scale ones.
Recommendations to overcome barriers Based on our analyses we come to the following conclusions regarding a strategy for market transformation in the elevator and escalator market: First of all a European standard of measurement for electricity consumption for elevators and escalators is needed. This kind of standard is the basis to allow for comparisons between more and less energy efficient technology and the existence of a standard will already contribute to raise awareness. Second elevators and escalators should become part of legislation and regulation concerned with the energy efficiency of buildings, namely they should become part of the Energy Performance of Buildings Directive (EPBD). Third campaigns and material directing attention at the issue of energy efficiency of elevators and escalators is needed. This third conclusion is to be combined with the fourth, providing easy accessible and understandable information for buyers of elevators and escalators to support decision making processes. The most important groups to be addressed in these campaigns are on the one hand those involved in the decision making for installations for new buildings, i.e. general contractors, architects and construction engineers, on the other hand those involved in maintaining elevator and escalators services in buildings, building administrators and operators. Standardization of measurement Today, the energy consumption of a single installation is usually unknown to its owner as well as to the maintenance company and the manufacturers. Manufacturers have recently started to invest time and effort in providing measurement data for their equipment, however, no consistent European or international standard exists. Precise and standardized data is the first step in identifying potentials for energy efficiency. Otherwise, it is not possible to compare different models or installations or make informed decisions about equipment. Thus, this gap needs to be closed as soon as possible, either via accelerating the ongoing ISO-process or via a European solution. First concepts how to measure energy consumption of elevators have been brought forward, e.g. by the German VDI4707 or by the E4-project. Thus, a rapid development of standard should be possible. Relevant legislative framework Next, elevators need to be included into the relevant framework of regulation and legislation. Up to now, elevators are neither included into building directives, e.g. EPBD, nor into those on electric equipment, e.g. EuP/ErP. The necessity for this is enhanced as many subsidized programs, e.g. for enhancing energy efficiency of buildings, draw on these directives (or their respective national implementations) for defining eligible projects. Raising awareness Setting measurement standards and complementing legislation will already contribute to raising awareness about energy efficiency to some extent. However, higher levels of awareness are necessary – especially on the side of administrators/operators/users – to secure that the energy efficiency of elevators is optimized. Main target groups for awareness raising measure are the stakeholder involved during the planning and construction of buildings, i.e. those taking the decision if new equipment is installed, as well as those stakeholders who are later using and/or operating an installation, i.e. those paying for the energy consumption and taking the decisions on retrofits. One way of raising awareness in several target groups is labeling equipment in a comparable and comprehensive way as it has been done for other electrical equipment, e.g. freezers and refrigerators. However, due to the multitude of types of elevators the development of a comprehensive labeling system may take time and it needs to be dynamic in order to adapt it to technological innovation. In the meantime, other measures to raise awareness should be installed. This is also important as labeling only addresses new equipment and does not include existing installations. Due to the long life-time of elevators, it is necessary that measures for market transformation address existing installations as well. First steps to raising awareness consist of developing dissemination material that provides information for different kinds of target groups and organizing workshops that provide information on this topic. Main target groups should include architects and construction engineers, construction companies that act as general contractors as well as building operators and administrators. While the first two groups
are most important in the process of installing new equipment, the last one is relevant in case of retrofits and modernization. To advise all of these groups on energy efficient equipment information material is necessary that is easily accessible and comprehensive – a topic that will be further discussed in the next section. Enhancing knowledge It is one of the general experiences of elevator experts that most clients have little knowledge about elevators. Furthermore, specialized consultants are only involved in a minority of project. Thus, raising awareness is not enough to enhance energy efficiency: Even if decision makers were aware of energy efficiency they would not know how to achieve this goal. Here again, standardized measurement turns out to be key for energy efficiency. Without comparable data for different models and types of elevators customers do not have the possibility to make an informed decision. Additionally, building on this, relevant information has to be accessible to customers e.g. via the internet or brochures. This includes, for example, check-lists about energy efficient components which may be consulted for retrofits [e.g. 9]. It is important to keep in mind that this information has to be directed at different target groups: to general contractors, individuals involved in the planning process of a building as well as to operators and administrators of buildings and building owners. Thus, several channels have to be used to communicate about the information sources once they are established.
Conclusion To sum up, this paper leads to the following conclusions: Notably, the potential reduction of standby energy consumption is an opportunity for energy efficiency that must not be disregarded: The energy need for standby could be reduced by 80 % if the best available technology was used. However, the share of standby mode in elevators represents 5 % to 95 % of the overall consumption which is a broad range. This broad range is on the one hand due to usage patterns - a higher number of trips usually increases the share of energy necessary for running. On the other hand, the energy consumption during running and standby is determined by the technology used and its energy efficiency. Based on the calculations for the estimation of savings, the results show that overall savings of more than 65% are possible. A reduction of 10 TWh is achieved in the 1st Scenario and of 12 TWh in the 2nd Scenario which translate into a reduction of around 4,4 Mtons of CO2eq and 5,2 Mtons of CO2eq, respectively, estimated based on the current electricity production. However, these scenarios are far from becoming reality. Elevators and escalators have long life cycles and several barriers to energy efficient technology are present in the market. The main barriers identified are lack of information and awareness, split incentive problems and an unclear state of knowledge on the economic efficiency of the technological measures. Several of these barriers may be addressed by the recommendations provided above: Implementing a valid standard of measurement on the electricity consumption for elevators and escalators, including elevators and escalators into the EPBD, raising awareness through campaigns and the provision of information material for relevant stakeholder groups and finally providing easily accessible and understandable information for buyers of elevators and escalators to support decision making processes.
Acknowledgments The E4 Project was mainly supported by the European Commission, Executive Agency for Competitiveness and Innovation, EACI.
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De Almeida, A. T., Patrão C., Fong J., Nunes U., Araújo, R. E4 - Energy Efficient Elevators and Escalators, “WP4 D4.2: Estimation of Savings”, Report elaborated for the EC, December 2009, www.e4project.eu (documents section)
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Standby and off-mode energy losses in office equipment - The SELINA project Aníbal de Almeida1, Andrea Roscetti2, Lorenzo Pagliano2, Barbara Schlomann3, Carlos Patrão4, David 5 5 Silva , Philippe Rivière 1 ISR-University of Coimbra - eERG, end-use Efficiency Research Group, 2Dipartimento di Energia, Politecnico di Milano, 3Fraunhofer ISI, 4ISR-University of Coimbra, 5Mines Paristech
Keywords Energy monitoring, electronic loads, standby and off mode consumption, low power modes, market transformation, test methods, office equipment
Abstract The introduction of energy labels, together with MEPS, implemented with EU Directives over the past years, has produced a very positive trend in the sales of more energy efficient appliances. Consumers have responded positively to this mandatory information scheme at the point of sales enabling the comparison of the energy-efficiency of various models of the same appliance family through their ranking. Despite these improvements electricity demand has increased and it a considerable increase in is expected due to the increasing number of electronic components in appliances that offer more and more functionalities and to the increase of the size of some key appliances as fridges or TVs. This paper presents the preliminary results of the SELINA (Standby and Off-Mode Energy Losses In New Appliances Measured in Shops) project, focusing on office equipment. The main objective of the SELINA project is to identify effective market transformation policies targeted at all the key stakeholders involved in the manufacture, distribution, sales and operation of appliances with standby and off-mode losses in order to achieve electricity and carbon emissions savings. The paper presents the analysis of the data acquired up to now during the large scale monitoring campaigns regarding standby and off-mode consumption as well as the methodology developed for measurement of these data. Energy consumption of the measured appliances in low power modes will be compared to the standby and off-mode European legislation and compared to data available, international literature and databases. Another key issue of the project is to find out the commerce/retailer awareness of energy efficiency in general and of low power mode consumption modes. Are retailers active enough in promoting energy efficient products towards their customers? Are they aware of the impact of low power modes? A short questionnaire was designed in order to evaluate the awareness of retailers, e.g. their knowledge and interest on labelling, standby consumption, energy star, efficiency classes, etc. Information is being gathered on the presence of the labelling on the equipments (inside and outside EU countries) and also of policies and actions to accelerate the market penetration of energy-efficient electrical appliances. Preliminary results of this awareness survey being conducted in stores are presented on this paper. Possible generic measures to reinforce the EU legislation are discussed on the basis of these preliminary results.
Introduction Although significant improvements in energy efficiency have been achieved in appliances technologies, during the period of 2004 to 2007 the end-use electricity consumption had an increase of 10.45% in the tertiary sector. This is a significant increase when compared with the growth rate for the period of 2001 to 2004, when an increase of 6.96% was registered [1] Some of the reasons for such increase in the residential and tertiary sector electricity consumption are associated with a higher degree of basic comfort and level of service and amenities (particularly in the new EU member countries) and also with the widespread utilization of relatively new types of loads whose penetration and use has experienced a very significant growth in recent years. 311
Office equipment (PCs, monitors, fax machines, photocopiers, printers, etc.) are the fastest growing users of energy in the tertiary sector, this is expected to double by 2020 [2]. The EL-TERTIARY European Project estimated that the office equipment electricity consumption represents around 5,3% of the tertiary sector in France, 6% in Italy, 14% in Germany and 7,5% in The Netherlands [2]. Based on a recent published estimation, in 2007 more than 48 million desktop computers and 59 million laptops were installed in non-residential applications [1]. In 2007, total standby consumption of home appliances in EU-27 amounted to around 43TWh, which is 5.4% of total residential electricity consumption [1]. In Germany, the share of standby is even higher (6.8% or 9.4TWh) [3]. On the other hand, substantial technical and behavioural saving options exist to reduce standby consumption. For Germany, electricity savings of 4.6TWh are estimated until 2020 if all saving options with regard to standby were applied. This means a halving of current standby consumption in the residential sector. On the part of manufacturers, the technical solutions reducing standby consumption, which are mostly cost-effective, are often not applied due to possible additional costs for the manufacturer, and also because it is not a market access requirement [1, 4]. The relevance of the standby and off mode energy consumption is illustrated by the fact that the IEA estimates that, even with a continuation of all existing appliance policy measures, the electricity consumption for ICT and consumer electronics will grow by almost 800% from 1990 to 2030. In the next figure, an overview of their estimations is shown.
Figure 1: Projected IEA electricity consumption for ICT and CE equipment, 1990-2030 [7] According to the IEA, by 2030, 15% of the total appliance electricity consumption in Europe could be due to standby functions. This represents the largest area of potential energy saving because efforts to introduce measures to reduce the standby and off-mode energy consumption have only started in the last 10 years. In the future, power demand will be influenced by technical improvement in equipment introduced by manufacturers, as well as by Minimum Energy Performance Standards, such as the one recently set by the European Commission (e.g. Commission Regulation (EC) No 244/2009 of 18 March 2009, implementing Directive 2005/32/EC of the European Parliament and of the Council with regard to ecodesign requirements for non-directional household lamps). In a recently completed Energy Intelligence for Europe (IEE) project, REMODECE (Residential Monitoring to Decrease Energy Use and Carbon Emissions in Europehttp://www.isr.uc.pt/~remodece), the electricity use of appliances in houses has been monitored in detail (with separate metering of lighting and individual appliances) in some 1.300 homes across the EU. In average the measured standby power is about 30Watt and electricity consumption is 169kWh per household per year, which is about 6.3% of the total annual electricity consumption per household. The standby energy of the end-uses metered during the REMODECE project amounts in total to about 21.5TWh for all households in the participating countries, and is responsible for about 9,4 million ton CO2 per year. For the tertiary sector the annual electricity consumption for the standby of office appliances in EU-27 countries is estimated to be 9,43 TWh [1].
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The SELINA project The name SELINA stands for Standby and Off-Mode Energy Losses In New Appliances Measured in Shops. The SELINA project is directed to characterize the EU market in terms of standby and offmode consumption in new electrical and electronic household and office equipment, being sold in shops, with a developed appliance specific measuring methodology. A large scale monitoring of new equipment is characterizing low power modes (“lopomos”), of the equipment being sold in a large sample of EU Countries. About 6000 pieces of equipment will be measured, in the period 2009-2010, before and after the entering in force of the European Regulation EC 1275/2008 regarding standby and off-mode power consumption. This will allow creating an equipment database with the market trends, which is a major tool for policy makers to define future policies and regulations. The groups of products that are being covered include: − Entertainment (Set Top Box, TVs screens of all sizes and technologies, DVD players and recorders, Video Projectors, Hi-Fi, Home Cinema systems, game consoles, all external Power supplies and Chargers associated with portable entertainment equipment); − Information and Communication Technologies - ICT (Desktop and Notebook Computers, Monitors, Printers, Fax machines, wired and wireless Routers, cordless Telephones, Answering Machines, all External Power Supplies and Chargers associated with portable ICT equipment.); − Large appliances (Washing Machines, Dishwashers, Tumble Dryers, Chillers, Air Conditioning devices, etc.); − Miscellaneous (Electronic Controllers for central heating/cooling and solar systems, home Alarm Systems Garage Door Openers, Occupancy Sensors / Automatic Light Switches etc). Another aim of the SELINA project is to propose a representative “basket of products” for which standby and off-mode power levels can be measured and tracked in any country around the world. This basket can be measured by interested parties to compare trends in standby and off-mode power within that country and across countries. International cooperation with institutions outside the EU, involved in similar efforts (IEA Implementing Agreement 4E (Efficient Electrical End-use Equipment) with an Annex on Standby, Energy Star/EPA in USA, Australia Standby Initiative, Swiss Federal Office of Energy) are being used to promote synergies in the definition of common approaches to characterize the market and to define realistic and cost-effective performance targets which can be achieved in a short time frame. The purpose of these standby and off-mode measurements on a common set of products is to characterize equipment consumption and to allow national and international comparison of these like equipments across different countries and regions. Such measurements will heighten the awareness of stakeholders of the magnitude of standby and off-mode power and will provide a focal point to highlight possible differences across regions between similar equipments. Such measurement will demonstrate the effectiveness of the policy mix used in individual countries and promote products that meet the standby power challenge. The SELINA project will produce a user friendly brochure with 4 to 8 pages (in each partner national language), with guidelines on equipment selection and operation. This brochure will be emphasizing not only energy and financial benefits, but also the reduction of the carbon emissions and the contribution to the EU climate change targets. It will provide intermediaries (retailers, energy agencies; consumer associations) with estimates of energy requirements and operating costs for electrical appliances, allowing consumers to make more informed electrical equipment buying decisions. The main objective of this project is to identify effective market transformation policies initiatives targeted at all the key stakeholders involved in the manufacture, distribution, sales, purchasing and operation of appliances with standby and off-mode losses. As a result of the future policy actions that may appear after the end of the project it is expected to achieve a huge cost-effective savings of electricity (80TWh projected by 2020) and carbon emissions (30MTons of CO2 by 2020).
The main objectives of the SELINA project The following aims are to be achieved during the project implementation: 313
6. 7. 8. 9.
Compilation in a database of information on the standby and off-mode electricity consumption of new equipment in the market (measured in shops); Compilation in a database of information on the standby and off-mode electricity consumption of new appliances in the market (manufacturers data), in each mode of operation; In order to facilitate for households and organizations to purchase energy efficient equipments will be produced, a Purchasing Guidelines Leaflet, including purchasing requirements and advices on purchasing and operating equipment; Identification of actions and policy instruments, through active international cooperation on products and standards that will reduce the standby and off-mode electricity consumption for each type of equipment. These include energy labeling, minimum energy performance standards, performance visibility and compliance, procurement, and innovation stimulation.
In the long term, project activities will aim to: 1. Increase of the penetration energy efficient equipment in the residential and tertiary sectors; 2. Increased awareness of consumers leading to an improvement of the consumer’s behavior in the selection and operation of the electricity consuming equipment; 3. Reduction standby and off-mode electricity consumption (the economic potential is about 80 TWh/year by 2020); 4. Reduction of the carbon emissions (the savings potential is over 30 million tons of CO2 by 2020), contributing to meeting the EU climate commitment and helping to mitigate climate change; 5. Increase and accelerate the availability of higher energy performance equipment in the market.
Methodology Monitoring and data analysis is very time consuming activity, but can bring a lot of reliable and useful information. Reliable data on electricity end-use consumption is the basis for good policy decisions. Without good data it is impossible to define relevant effective strategies and policies. One of the most important tasks of the project, before the beginning of the measurement campaigns, was to develop and confirm a robust, accurate and safe measurement methodology for the standby power requirement of a basket of Energy Using Products (EuP) that can feasibly be tested in a shop floor environment. Careful consideration was to be given to the measurement methodology recommended for these products in International Standards (IEC 62301). The problem of consistent measurement instrumentation for all the partner testing teams and the format of a testing guidance manual covering each product suggested in the “basket of products” was also to be addressed and resolved. Many of these product types are global commodities with small differences in standby and off-mode power levels (some may be due to voltage and frequency effects). However, some appliances may be subject to regional differences as a result of local standby programs or other influences. For these appliances, which are more regional in nature in terms of their design or configuration, there may be larger variations in standby and off-mode power levels between countries. Power management and efficiency improvement of all modes of operation is increasingly important (for instance "Always on" will be more and more common in the future for a variety of appliances), hence we are metering whenever possible other low power modes besides standby mode. Several tests were conducted in a reasonable measurement equipments available at the market, in order to choose the most accurate. Each partner acquired several measurement equipments, all of the same model, which will provide consistent results across all the testing teams and meet requirements for low power accuracy and PC interface for reliable reporting. All power measurements were taken with a AD Power Wattman HPM-100A meter. This is a meter with a wide measurement range (9mW ~ 3.75kW ±0.5%), with 0,001W resolution. The minimum recording requirements for each product are, Power (W), Power Factor (PF) and Voltage (V) in the following modes, as defined in the regulation, chapter 2 [6]: - Off (product cannot be put into standby mode or any other mode without physical activation of a switch or control mounted on the product); connected to mains without any function (minimal off mode of the regulation) REGULATION “(a) Power consumption in ‘off mode’: 314
Power consumption of equipment in any off-mode condition shall not exceed 1,00 W.”
− Standby product can be reactivated by a remote control and/or if the product has a display/clock. In the case of a product with an external power supply (EPS) a further measurement of W, PF, and V, should be made with the product disconnected from the EPS and full details of the EPS rating plate recorded. REGULATION “(b) Power consumption in ‘standby mode(s)’: The power consumption of equipment in any condition providing only a reactivation function, or providing only a reactivation function and a mere indication of enabled reactivation function, shall not exceed 1,00 W. The power consumption of equipment in any condition providing only information or status display, or providing only a combination of reactivation function and information or status display, shall not exceed 2,00 W”
It was developed a macro for an “xls” file that is capable of communicating with the measurement equipment, inserting into the correct cell each necessary requirement data of the product. These way human errors are avoided and the measurement campaigns are less time consuming. Detailed guidance for product specific measurements and related information requirements were also incorporated into the “xls” file, and shown automatically when an appliance type is selected.
Measurement and awareness survey in shops and stores The shop measurements allowed following the implementation of the European Regulation EC 1275/2008 regarding Standby and off-mode power consumption. The measurements were made in shops across Europe following the previously described methodology.
Measurements Results About 6000 equipment are to be measured in the project. Over 3682 measurements have already been conducted, 473 corresponded to office equipment: computers (desktop and laptops), computer monitors, printers, facsimiles, copiers, scanners and multi-function devices. Both measured off-mode and standby correspond to the EU Regulation definitions. Regarding the first set of measurements of the SELINA project during 2009, Figures 2 shows “offmode power” and Figure 3 show “standby power”. - Values between the 25th and 75th percentile - Average
2010 upper level 2013 upper level *-The numbers after each product type represents the number of measurements. **- The yellow bar represents the distribution, where 50% of the measured consumption can be found. The values placed above and below the yellow bar, represented by a solid line, correspond to the other two distributions where the other 50% of measurements can be recorded.
Figure 2– Off-mode power consumption per equipment type
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Regarding off-mode power consumption, the power of almost all measured equipments measured is below the EU Regulation limits [6] for 2010 (limit for 2010 = 1W). Only desktop computers appear not to meet these limits. The maximum recorded value for off-mode was 5.4 W belonging to a multifunction device. As explained before, the EU Regulation defines two different limits for standby, one for products with reactivation functions only (limit equal to 1 W in 2010) and another limit for products with display/clock (limits equal to 2 W in 2010). It was not possible to record standby values for some of the measured equipments, like printers and multi-function devices, because this mode was not available. This was due to the fact that no cart-ink was installed in the equipment resulting in an anomalous operating mode “error-mode”. However for scanners any equipment presented standby mode.
In figure 3 are shown the products with only reactivation function.
- Values between the 25th and 75th percentile - Average
2010 upper level 2013 upper level *-The numbers after each product type represents the number of measurements. **- The yellow bar represents the distribution, where 50% of the measured consumption can be found. The values placed above and below the yellow bar, represented by a solid line, correspond to the other two distributions where the other 50% of measurements can be recorded.
Figure 3– Standby power consumption for equipments with reactivation only The maximum recorded value was 49.4 W for a computer monitor model. The measured values show that desktop computers are above the regulation limits for standby power consumption, both in standby mode, and in off-mode. Regarding the products with a display/clock while in standby mode, only 7 facsimiles models had an electronic display. For these products the average standby consumption was 2.22 W, only slightly higher than the Regulation limits (Regulation limit for 2010 equal to 2 W). Almost every measured product already meets the 2010 directive threshold, with the exception of computer desktops. It should also be reminded that computer laptops, which represent the biggest sample (192 measured products), are in agreement with the 2010 directive limits already since 2009.
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Figure 4- Compatibility of the appliances low-power consumption with the EC 1275/2008 directive limits [8] The results of the measurement campaign have shown a promising adaptation of the office equipment to the limits set by the regulation. In general, it can be said that office equipments responded to the 2010 regulation limit the year before it entries into force. However a more precise evaluation of the low power modes will be possible once the 2010 measurements are finished. The results presented in the Figure 4 appear promising since only 9.3 % of the measured products have power consumption in off-mode above the regulation threshold for 2010. For standby only 22.9 % of products are above the 2010 regulation threshold. However when comparing the measurement results with the 2013 regulation threshold it can be seen that further development is needed in the next few years because, for both off-mode and standby, more than 50% of the measured appliances do not comply with the 2013 regulation thresholds.
Measurement comparison Next, a comparison is made between the recorded data and the reference values used in the EuP TREN/Lot 6 [4]. Because there was no available data for multi-function devices, scanners and copiers in the EuP TREN/Lot 6, values from other studies were used [7, 8]. The compared values are averages of the recorded power consumption.
Figure 5 – Off-mode power consumption values comparison An average reduction of 70% in off-mode power consumption values can be observed in Figure 5, when comparing the SELINA measurements with other studies realized in 2005 and 2008 [7, 8, 4].
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Figure 6 –Standby power consumption values comparison Figure 6 shows that the same trend for standby as in off-mode. An average reduction of 30 % is observed when comparing the SELINA measurements with other previous studies. As a general outcome of this comparison it can be said that office equipments exhibit a positive evolution over the last few years in terms of low power modes consumption thanks to the implementing measure of the Directive 2005/32/EC on Ecodesign of products, the European Regulation EC 1275/2008.
Retailers Awareness In the SELINA project frame a retailer’s awareness survey with a total goal of 300 questionnaires in 12 different European countries is being done. Until now 128 questionnaires were answered by salesmen from Romania, Belgium, and Denmark. The first results show that 90 % of retailers try to give emphasis to energy savings that could benefit the end-user. However other features like equipment price, brand and design appearance play an important role during equipment sale and for client decision. In the interviewed retailer’s opinion, the use of additional information over what contains the Energy labels, eg energy consumption of the equipment in different modes could change the client decision regarding efficient equipment, i.e. to buy efficient equipments. It has been proposed by some retailers to display the off-mode and standby wattages on energy labels: there is however a risk that the customer may choose the product based on the low power modes consumption rather than based on the total consumption of the product. For products where low power mode consumption and main function consumption are comparable, integrated indices should be adopted. In Figure 7 it can be seen that 23 % of retailers are still not aware that equipment in off-mode can consume energy.
Figure 7 – Retailer’s answers 318
Policies for market transformation In the European Union, the most important policy tool directed at reducing energy consumption of electrical appliances is the Eco-design Directive (2005/32/EC). It establishes a framework under which manufacturers of energy-using products will, at the design stage, be obliged to reduce the energy consumption and other negative environmental impacts occurring throughout the product life. The Directive was revised and enlarged to all energy-related in 2009 (2009/125/EC). In December 2008, the Commission adopted the Regulation No. 1275/2008 for implementing the Eco-design Directive with regard to requirements for standby and off-mode electric power consumption of electrical and electronic household and office equipment. The regulation, which comprises a wide range of products (household equipment, information and communication technologies, consumer electronics, other products as toys etc.), stipulates that from 2010 power consumption of this equipment in any off-mode condition and in any condition providing only a reactivation function shall not exceed 1 W and equipment also providing information or status display shall not exceed 2 W. From 2013, these limits are further strengthened to 0.5 W and 1 W respectively. Minimum energy performance standards (MEPS), as they are set under the EU Eco-design Directive, are a suitable policy tool in order to remove the worst performing products from the market. They are, however, not sufficient to promote the best performing products and to overcome other important market failures and barriers as e.g. information deficits of consumers and retailers. Since this is more relevant for energy consumption in active mode than in standby and off-mode, the analysis of policies for market transformation within the SELINA project is not restricted to polices only focusing on standby, but all operation modes are considered. There is a wide range of additional policy tools in order to bring about long-term market transformation towards more efficient electrical appliances: − Mandatory or voluntary energy efficiency labels, which aim to provide consumers and retailers with information at the point of sale and enable suppliers to gain market recognition for efficient products; − Fiscal and financial measures as e.g. grants or tax reductions for highly efficient appliances, or low interest loans; − Market-based instruments as the establishment of white certificate schemes creating a market for energy efficiency; − Co-operative instruments as voluntary agreements with producers of energy-using appliances, voluntary DSM measures of energy suppliers or technology procurement for energy efficient appliances; − Information and education programs and activities both addressing consumers (as buyers and users of electrical appliances) and retailers. A first overview of the policy instruments which are used in a country to enhance the market transformation towards energy-efficient appliances can be gained from existing online databases, as e.g. the IEA Energy Efficiency Policies and Measures Online Database22 or the MURE measure database including all EU Member States plus Norway and Croatia23. A recent IEA publication about electronic devices [9] also gives on worldwide overview of policies for energy efficient electronics. Nevertheless, these sources mainly refer to general policies addressing energy-efficient appliances at the national level, whereas specific programs and activities addressing consumers and retailers not only at the national level, but also at the level of regions or municipalities, are rarely included. In a survey among retailers in all EU Member States e.g., many suggestions have been made by the retailers how to motivate consumers to buy more energy-efficient appliances at the point of sale which go beyond the usual policy tools (Figure 8).
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http://www.iea.org/textbase/pm/index_effi.asp
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http://www.mure2.com/
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Energy-saving appliances should concentrate on the aspect of energy-efficiency
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Improve the design of the label.
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Provide an energy-saving calculator.
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Special training for shop personnel. Provide more information in the internet about the label and energy-efficient appliances.
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Public promotion campaigns for the label.
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Provide a selection of the most energy-efficient appliances.
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Show purchasing costs compared to energy efficiency. Producers should offer cheaper energy-saving appliances.
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Even more energy-efficient appliances should be developed.
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Financial incentives for the purchase of energy-efficient appliances.
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Figure 8 - Suggestions from retailers in all EU countries how to motivate consumers to buy more energy-efficient appliances (source [10]) Therefore, one target of the SELINA project is the collection of this kind of specific actions directly addressing consumers and retailers both taking into account actions aiming at the reduction of total energy consumption of the appliances in all operation modes and at standby and off-mode consumption in particular. This includes information and education programmes by energy agencies or other institutions, voluntary activities by retail trade or manufactures, financial support for efficient appliances, additional voluntary labels or the development of information tools for retailers. The measure collection is based on a common template both including a formal measure description by type of equipment addressed, actor, target group and status, and some detailed on the contents of the measure, the costs and results with regard to energy and standby savings. The first results of this measure collection, which is still going on, are shown in Table 1. In most countries, information programmes (esp. brochures, leaflets, websites, national labels) are the dominating measure type. In some countries, however, financial subsidies for very energy-efficient appliances, often paid by an energy utility and not by the government, play an important role, too (e.g. in the Czech Republic or Switzerland). Energy savings are indicated for all measures for which this information is available. In general, the impact of a financial programme is easier to quantify than the single impact of an information campaign, which often serves as an accompanying measure for regulations (labels, minimum efficiency standards) or fiscal and financial measures. Table 17-Examples for policies and actions to accelerate the market penetration of energyefficient electrical appliances in selected SELINA partner countries Country Measure title Description and results Austria Quick-Check “Quick-check” is an online tool to calculate the electricity consumption of a private household. It was developed by E-Control and the Austrian Energy Agency and shall allow the user to get more information on the energy consumption of all electrical appliances available in the household. In addition, electricity saving options are given and the benefit of these possible savings is calculated in Euro/kWh. Czech Rep. “Scrap Premium” In 2009, the CEZ group initiated a 2 month programme in cooperation with on white two selected electronic retail stores. Customers got a premium of 1000 CZK appliances (ca. 38 Euro) when buying a new most efficient white appliance and handing over the old appliance, which was ecologically recycled. It is estimated that roughly 50% of energy consumption for a given appliance may have been saved by this measure. Czech Rep. Prazak family is This is an activity in Prague which was based on the EU-IEE project saving with PRE REMODECE. Six most “energy wasting” families have been chosen and got an energy advice, resulting in energy savings of 14 to 31 %. The total savings in the families amounted to more than 6 MWh/year. Linked to that, 320
Czech Rep.
Discounts and subsidies under EnergiePlus+
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Campaign “Turn off the switch – or spend money on nothing” AutoPowerOff plug banks
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Initiative EnergieEffizienz
Italy
Budget law 2007 and 2008
Italy
Law 166, 20/11/2009
Sweden
Technology procurement
Switzerland
Energy label for coffee machines Subsidies for A++ devices
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the biggest electricity distributor in Prague, PRE, initiated a large energy saving campaign, in which these families were the actors. The additional savings of the campaign have not been quantified. Activity of EON, which is a big electricity and gas supplier in the southern parts of the Czech Republic. In cooperation with one producer of white appliances and a special retail chain, a bonus is paid for a purchase of energy efficient white appliances and discounts are given for the purchase of efficient light bulbs and energy saving devices (switch socket power boards, timer). In winter 2003/2004, a campaign was carried out giving information on standby consumption and how much money can be saved by turning off the appliances. The campaign was well-known in the population. Campaign of the Danish Electricity Savings Trust in 2007/2008 promoting the wider use of AutoPowerOff plug banks in cooperation with producers and several major retail chains. The total costs of the campaign amounted to around 1.2 million Euro. The annual savings per household per plug range between 25 and 137 kWh/year. The Initiative EnergieEffizienz is a nationwide platform for action targeting the efficient use of electricity in all consumer sectors. It is organised by the German Energy Agency (dena) as a public/private partnership project in cooperation with energy supply companies. Retail trade and craftsmen, existing consumer advice centres and regional energy agencies are also integrated in the concept of the campaign. With regard to private consumers the campaign is especially focused on reducing standby losses, supporting efficient lighting with high comfort and raising energy efficiency of “white” household appliances. New installation and/or replacing of high efficiency motors of electric power between 5 and 90 kW, of variable speed drives (inverters) on installations with electric power between 7.5 and 90 kW, replacement of refrigerators, freezers and combinations thereof by similar appliances of energy class not inferior to A+ will have a gross tax deduction equal to 20% of the amounts remaining payable by the taxpayer, up to a maximum deduction of €1500 per motor or inverter (in a single installment) and 200€ per refrigerator. Operation has to be carried out by 31 December 2010. Creation of a 1 Million € fund for public information campaigns (in particular on incandescent bulbs phase-out and stand-by consumption reduction). Since the 1990s, about 40-50 “technology procurement” projects have been performed in Sweden. Though no projects are going on now, many “technology procurement” inspired working groups have been established with purchasers groups. The Swiss Government introduced a voluntary energy label for coffee machines following the example of the EU energy label. There are different programs and actions from Swiss utilities to promote highly efficient white appliances by subsidizing A++ devices. As an example, an electricity saving funds of Zuerich pays up to 400 CHF per purchased A++ freezer or refrigerator.
In addition, pilot actions will be carried out within the SELINA project in order to test the new information tools on standby consumption which have been developed within the project (online database including information on best and worse standby consumption of the appliances measured within the project, internet-based calculator calculating energy savings for each of the appliances in the database, brochure including guidelines of equipment).
Conclusions It is expected that SELINA project can support the successful national implementation of the regulation implementing the Eco-design Directive with regard to standby consumption by providing information on the 321
present status from the measurement campaign. The project can also help to embed this implementation in a broader national strategy to enhance the market transformation towards energy-efficient appliances since it gives a deeper insight into retailer’s attitudes towards energy-efficient appliances and an overview of successful and innovative policy measures at the level of retailers and consumers. The SELINA project shows very important results both in technological and in market transformation: − so far, about 70% of the products metered in the project have a better performance in off-mode consumption than recorded in the past three years: the commission regulation appears to work in the right direction and manufacturers to have adapted before the legislation entries into force; − regarding standby power, the efficiency increase is lower, (although almost 30% of reduction is observed) and efforts are still required to reach the legislation requirements of 1 W in 2013; − Both for standby and off mode however, a considerable number of products reaching the thresholds of the European regulation on standby and off mode have already been available at the point of sale in 2009, i.e. before the regulation became effective; − Despite existing efforts, some more target group specific information about energy consumption both in active mode and in low power modes in shops could further support the market diffusion of energy efficient products.
References and Bibliography [1]
[2] [3]
[4] [5] [6]
[7] [8] [9] [10]
[11]
Bertoldi, Paolo; Atanasiu, Bogdan, Electricity Consumption and Efficiency Trends in European Union, Status Report 2009, European Commission, Joint Research Centre Institute for Energy, Renewable Energy Unit, Luxembourg: Publications Office of the European Union, 2009, online: http://re.jrc.ec.europa.eu/energyefficiency/publications.htm, ISBN 978-92-79-13614-6 E. Gruber, S. Plesser, R. Dusée, I. Sofronis, P. Lima, P. Rivière, A. Rialhe: "ELTERTIARY, Monitoring Electricity Consumption in the Tertiary Sector", Intelligent Energy, D26 - Report on the Project Results, 2008 Fraunhofer Institute for for Reliability and Microintegration (IZM) / Fraunhofer Institute for Systems and Innovation Research (ISI): Abschätzung des Energiebedarfs der weiteren Entwicklung der Informationsgesellschaft. Study on behalf of the Federal Ministry for Economics and Technology (BMWi). Berlin, Karlsruhe, 12 March 2009, online: http://www.isi.fraunhofer.de (English summary available) Fraunhofer Institute for Reliability and Microintegration (Fraunhofer IZM): EuP Preparatory Studies “Standby and off-mode losses” (TREN / Lot 6), Final Report, October 2007, online: http://www.ecostandby.org International Energy Agency, Gadgets and Gigawatts-Policies for energy efficient electronics, OECD/IEA, 2009, ISBN 978-92-64-05953-5 European Commission. Commission Directive (EC) No 1275/2008 of 17 December 2008 implementing Directive 2005/32/EC of the European Parliament and of the Council with regard to ecodesign requirements for standby and off mode electric power consumption of electrical and electronic household and office equipment, Official Journal L339, 18.12.2008.pp. 01-08.Can be download at: http://ec.europa.eu/energy/efficiency/ecodesign/legislation_en.htm Schlomann, Barbara et al., Technical and legal application possibilities of the compulsory labeling of the standby consumption of electrical house-hold and office appliances, Karlsruhe, Munich, Dresden, 13 June 2005. Meier, Alan et al, Lawrence Berkeley National Laboratory, Low-power Mode Energy Consumption in California Homes, Buildings End-Use Energy Efficiency, September 2008 IEA (International Energy Agency): Gadgets and Gigawatts. Policies for Energy Efficient Electronics. Authors: Marc Ellis, Nigel Jollands. OECD/IEA, Paris, 2009, online: http://www.iea.org Schlomann, B., Gruber, E., Roser, A., Herzog, T., Konopka, D.-M.: Survey of Compliance Directive 92/75/EEC (Energy Labelling). Study by Fraunhofer ISI, IREES (former BSR Sustainability) and GfK on behalf of the European Commission (DG TREN). Karlsruhe, Nuernberg, January 2009, online: http://www1.isi.fraunhofer.de/e/index.htm SELINA- Standby and Off-Mode Energy Losses In New Appliances Measured in Shops , WP2 D2.2 - Testing Manual “Standby and Off-Mode Energy Losses In New Appliances Measured in Shops”, Report elaborated for the EC, November 2009, http://www.selina-project.eu
Acknowledgments The SELINA Project is mainly supported by the Intelligent Energy Europe Programme of the European Union 322
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MICROPOLYGENERATION APPLICATIONS FOR MILD CLIMATE Sergio Sibilio 1, Carlo Roselli2, Maurizio Sasso2 Built Environment Control Laboratory - Seconda Università degli Studi di Napoli, Italy 2 DING Università degli Studi del Sannio, Italy
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Abstract Polygeneration, in its well known configuration as Trigeneration, is the possibility to supply, with high performance, two or more energy requirements (electric, cooling and heating) to an end-user; in many cases, mainly in tertiary sector (hotels, offices, shopping centers, commercial buildings, hospitals, airports, sports centers, …), a widespread use of trigeneration systems has allowed energetic, economic and environmental benefits. Lately this techonology is being revealed attracting in Mediterranean area, during warm season, where has growth an increasing demand of cooling energy in small tertiary sector generally satisfied by electrically-driven units; this trend has involved an increase power generation capacity of electric utilities and a summer peak load of electric energy consumption with the related problem of electric black-out. At the Built Environment Control Laboratory (Seconda Università di Napoli, Italy) is running a system based on gas fuelled internal combustion engine coupled with an Air Cooled Water Chiller, ACWC, and a ThermoChemical Absorption system, TCA; the assembly supplies thermal (heating and hot water, 12 kW), electrical (6 kW) and cooling energy (7.5 kW) to a part of a building with offices and laboratories under actual operating conditions. At Sannio University an advanced desiccant air handling unit coupled with a reciprocating internal combustion cogenerator is in a tuning phase. The Micro Combined Heat and Power system, MCHP, supplies thermal energy (12 kW), recovered by engine cooling and exhaust gas, to the regeneration of the sorption material (silica gel) of the desiccant wheel. An external thermal load allows to simulate domestic hot water requirements. This paper deals with the applications of two Micro Combined Cooling, Heating and Power systems, MCCHP, the so-called "Domestic Trigeneration" or "MicroTrigeneration" system, under real operating condition for mild climate in South Italy.
Keywords: Trigeneration, Thermochemical Accumulator, gas fuelled engine, experimental plant
Introduction The term trigeneration [1] describes an energy conversion process with combined cooling, heating and power generation, CCHP; the system consists basically of a CHP module generating electricity and heat that, depending on the demand, is either used for heating or cooling purposes or both; as a consequence a trigeneration system is used wherever there is demand for heat, cooling and power, and its key components are a combined heat and power systems and a thermally driven chillers (TDC). The trigeneration has an application area that ranges from small residential to large commercial buildings (office, hotels, schools, sports, entertainment centres, hospitals, airports, etc.), and from small trade to industry facilities. In buildings (residential and commercial) the CCHP system produces heat for domestic hot water, space heating or desiccant dehumidification and cold for space cooling or air-conditioning. The major advantage of trigeneration is the efficient fuel usage, that, in comparison with conventional power generation systems can raise up to 60%; this leads to a lot of benefits: • primary energy saving, • more efficient fuel usage with saving fuels and money (economical benefits), • less greenhouse gases produced (climate change mitigation),
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• energy security of the country/region, • positive impact on economy. At the same time, some drawbacks still remain to the large diffusion of such systems: • components that are in R&D phase or in a pre-selling phase with high first cost, • weak financial supporting actions to ensure a suitable back period (possibility to obtain funds as well as to sell the electric surplus to the grid at good price), • lack of trial data to fill the gap about the optimization between the systems and the user load profile to define several operating strategy and their impact on system optimum performances, • insufficient political support mechanisms and administrative hurdles such as electric network grid connection. Over the abovementioned framework, it's necessary to underline that, in the last years in many European country, during warm season, there has been an increasing demand of cooling energy generally satisfied by electrically-driven units; this trend has involved an increase of power generation
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capacity of electric utilities and a summer peak load of electric energy consumption with the related problem of electric black-out. This problem has been the driving force to an increasing interest to microtrigeneration systems fuelled by natural gas, especially in the South of Europe. With reference to the industrial sector, a recent study [2] assessed that trigeneration could be considered as one of the most effective means to increase the efficiency of electricity generation and to decrease fuel consumption and associated emissions. Unfortunately up to now the technical potential for applications was not fully developed due to the lack of visibility and adverse financial appraisals. The study looked at 4 sectors (food, pulp and paper, refineries and chemical sectors, considering heat loads above 10 MWt) whereas the heat demand needed for their processes can be supplied by means of a cogeneration plant. The project aims to answer at a number of questions such as where the substantial demand for heat in industrial processes in Europe is located, which technological solutions have been selected in the past, which technology is being considered in new schemes, what are the applications for large-scale trigeneration currently found in industry or whether trigeneration is considered an appropriate and competitive option for industry or not. Regarding tertiary sector [3], at the present the prospective customers could be preferably found among: • Medium size hotels (< 200 rooms), • Small hospitals (< 200 beds), • Office buildings (< 4,000 m2), • Small supermarkets. Medium size hotels and small hospitals are likely to constitute the ideal application field. According to statistics of the main chain hotels, micro-trigeneration has the potential to find application in about 50% of the chain hotels of EU15 (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal, Spain, Sweden and the United Kingdom), for a total of nearly 7,000 installations. Considering the totality of the hotel sectors, the number of suitable installations can likely increase up to 70,000. In the health sector, a reasonable estimate of hospitals suitable for micro-trigeneration installations should be in a range from 4,000 to 6,000 units in the EU15. Finally, referring to the residential sector, trigeneration potential in buildings in European countries is hard to estimate [4]. This task will be thoroughly studied within the framework of the PolySMART project. Some results has been related to country specific situation: for example CHP (and hence CCHP) potential in United Kingdom is estimated to be around 17% of total projected electricity production in 2010. Around 15% of this potential exists in individual buildings. Some 40 million homes in old European Union countries are said to be suitable for micro-CHP (and hence micro-CCHP) systems. Sigma Elektroteknisk of Norway estimates a yearly market potential for Micro-CHP of some 800,000 units per annum only in Europe. Taking under consideration that the cooling market in Europe is far from saturation (with only 2% ÷ 5% air-conditioning units per household [4]) and growing very fast, it can be concluded that strong potential for combined heat cold and power also in buildings exists.
European legislation affecting Trigeneration European legislation and policies [5] can play a fundamental role in defining the framework conditions for the current and future use of trigeneration and hence, it's important to provide a picture of the most important pieces of European legislation and by outlining how they could affect trigeneration; among them it can be considered:
Cogeneration The CHP Directive [6] on the promotion of cogeneration based on a useful heat demand in the internal energy market, creates a framework for the promotion and development of high-efficiency cogeneration. The Directive covers all existing and future cogeneration technologies and it introduces methods to calculate "electricity from cogeneration" and to determine the efficiency of installations.
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Emissions Trading Directive The Emissions Trading Directive [7] establishes a scheme for greenhouse gas emission allowance trading within the Community. It applies to a range of large emitters and thus many existing or potential CHP installations. Among several expectations, Emissions Trading could influence the increase of the marginal cost of fossil-fuelled power generation and the price of electricity; these factors were seen as likely to push towards more investment in low-carbon and high-efficiency generation, such as trigeneration
Energy Performance of Buildings The Buildings Directive [8] on the energy performance of buildings, lays down a general framework to devise a methodology to calculate the integrated energy performance of buildings, for which Member States have to define minimum requirements. The calculation process has to take into account the “positive influence of electricity produced by CHP” and of “district or block heating". This directive application can stimulated the trigeneration diffusion by the requirement to integrate its benefits into the calculation of the energy performance of buildings. Moreover, referring to the air-conditioning and cooling in buildings, the Directive contains terms which are relevant for cooling applications in general and when considering the implementation of thermally driven cooling technologies
Energy end-use efficiency and energy services The Directive on energy end-use efficiency and energy services [9] aims to boost the cost effective and efficient end-use of energy in the Union by establishing a framework for the creation of a competitive European market for energy services. Of particular interest for the trigeneration is the fact that the European Parliament has included CHP (and micro-CHP in particular) into the list of examples of where Member States may develop and implement energy efficiency measures. The energy enduse and energy services directive relates directly to trigeneration as its main focus is on demand side management in residential and retail sector
Internal Market for Electricity The Electricity Directive [10] for the internal market in electricity, defines common rules for the generation, transmission, distribution and supply of electricity. Authorisation procedures for new generators can include requirements related to environmental protection and energy efficiency, while distribution system operators have to consider energy efficiency. The connection of new generators to the transmission and distribution networks has to be based on objective, transparent and nondiscriminatory criteria, and all costs and benefits from connecting generators using renewables, CHP and/or distributed generation have to be taken into account. It is possible identify however several important issues that directly impact the viability and/or attractiveness of trigeneration.
Internal Market for Natural Gas The Gas Directive [11] for the internal market in natural gas, establishes common rules on the storage, transmission, supply and distribution of natural gas; legal unbundling of network activities from supply is required like in the Electricity Directive. This Directive can have an great jmpact on trigeneration because of much of the EU’s installed trigeneration capacity is fuelled by natural gas and therefore the opening of the gas market has been a significant development for operators.
Taxation of Energy Products and Electricity The Energy Taxation Directive [12] restructures the Community framework for the taxation of energy products and electricity; this Directive widens the scope of the EU's minimum rate system for energy products, previously limited to mineral oils, to all energy products including coal, natural gas and electricity. It also provides for national incentives to encourage energy efficiency and emissions reduction. The Directive provides the possibility to support the development of high-efficiency cogeneration through preferential tax regimes.
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Electricity from Renewable Energy Sources The "Renewables Directive" [13] on the promotion of electricity produced from renewable energy sources in the internal electricity market sets an EU-wide target of renewables share in electricity production by 2010. The Directive has an impact for trigeneration from renewables through quantified national targets for consumption of electricity from renewable sources of energy, national support schemes plus harmonised support system, simplification of national administrative procedures for authorisation and guaranteed access to transmission and distribution of electricity from renewable energy sources.
European projetcs supporting Trigeneration There have been several trigeneration related projects realized within EU supported programmes, many of them ended in the last years and few are currently running or are in a start-up phase; they were mainly related to a small and medium trigeneration capacity range. Polysmart The main goal of the project [14] is to support the development of a new market for small and medium capacity trigeneration and to demonstrate the cost-effectiveness and reliability of small-scale combined heat, cooling and power units for a wide range of buildings and industrial applications. In the project twelve different combinations of technologies (absorption and adsorption chiller) and applications (residence, office, winery etc) will be realised and monitored extensively. The project involves manufacturers of thermally-driven cooling machines and manufacturers of CHP systems. Eight demonstration sub-projects using different thermally-driven cooling technologies has been carried out as a main activity at twelve sites in seven European countries for a wide spectrum of applications. Many different combinations of thermally driven chillers and CHP systems has been developed to the pre-commercial product stage. This comprehensive project aims to achieve substantial progress in the technical and market development of micro-CHCP systems using advanced, small and medium-scale, thermally-driven air-conditioning and refrigeration technology. ProEcoPolyNet EcoPolyNet [15] is a network for the promotion of Research and Technology Development (RTD) results in the field of Eco-building technologies, small trigeneration and renewable heating and cooling technologies for buildings The ProEcoPoly-Network pursues different overall goals: • editing RTD results to promote and disseminate efficient and innovative building-related energy technologies; • complementing dissemination carried out within similar individual Framework Programme projects; • increase the level of information and know-how transfer throughout Europe by linking leading experts and specific organisations in a network and by implementing joint activities; • contribute to the creation of a European Research Area by strengthening the co-operation between actors and institutions. The main types of actions are networking, screening and bundling of RTD results, exchange of best RTD practice, promotional RTD events, marketing campaigns and material. Hegel The HEGEL Project [16] brings together key trigeneration stakeholders and organisations from across Europe and the main objective of the HEGEL project is to develop, demonstrate and compare high efficiency applications of small-scale and micro-trigeneration for the civil and industrial sectors, based on innovative technologies. Three demonstration plants have been constructed and tested: a trigeneration plant installed in Torino (Italy), a microturbine in trigeneration mode with two air-cooled ammonia-water absorption cooling cycles installed Barcellona and a “Combi System” cogeneration plant consisting of the combination of a reciprocating engine and a Rankine cycle engine operated on the exhaust gases of the reciprocating engine; this unit has been installed in Turkey. POLYCITY POLYCITY [17] is a project of the CONCERTO initiative, co-funded by the European Commission. In the course of the POLYCITY Project, three large urban areas in Germany, Spain and Italy will be
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developed, particularly in the field of energy optimisation and the use of renewable energies. The project deals with different aspects of urban conversion: new constructions in the town of Cerdanyola del Vallès at the city edges of Barcelona with trigeneration energy generation, the conversion of an old city quarter in Turin with grid based energy supply and new building constructions on a former military ground in the town of Ostfildern near Stuttgart with biomass heat and electricity supply. Euroheat & Power Euroheat & Power [18] unites the combined heat and power, district heating and cooling sector throughout Europe and beyond, with members from over thirty countries, including all existing national district heating associations in EU countries, the majority of new EU Member States, utilities operating District Heating and Cooling (DHC) systems, industrial associations and companies, manufacturers, research institutes, consultants and other organisations involved in the CHP/DHC business. This appears a very promising sector because district heating and cooling will play a significant role in the supply of low-carbon heating and cooling in Europe. An international study co-financed by the European Commission [19] confirms the possibility of saving an extra 400 million tons of CO2 yearly (corresponding to 9.3% CO2 reduction – thus more than the whole Kyoto target!) with more District Heating and Cooling across 32 European countries. Creating conditions for the expansion of district heating and cooling schemes will thus secure a more sustainable energy system and a brighter energy future.
Technological framework The most common and flexible system is a decentralized trigeneration; in this case the heat and cold are generated and consumed onsite, while power is either consumed onsite or fed to grid. A considerable number of RTD projects have been or are under implementation in the course of the EU Framework Programmes, Demonstration Programmes and under national R&D programmes in the EU member states as well as in non-EU countries, and small and micro trigeneration systems in the range of some kW are becoming more and more popular. All the project are based on micro cogeneration units and thermally driven chillers that are already commercially available; they constitute the basic components of a micro-CCHP system because it is a logical step to combine micro CHP-systems with small TDC-units to develop so called microtrigeneration systems CHP units At the moment microcogenerators based on Reciprocating Internal Combustion (RIC) and Stirling engines [20], are already available on the market and a large R&D activity aims to produce in the medium and long period small commercially available units based on fuel cells, on gas and steam turbines [21]. Our analysis will be focused only on the microcogenerators based on RIC engines. Many efforts were spent to develop new small displacement engine to stationary use and to allow the engine heat recovery, with a particular attention to the design of the exhaust gas heat exchanger, that is also the engine muffler. These engines achieve small installation space, high mechanical (25-35%) and thermal (50-56%) efficiencies, low noise (< 50 dB(A) at 1 meter) and vibrations, low maintenance (one change of spark plugs and oil a year, corresponding to 2,000 hours) and long life service (20,000-40,000 hours, corresponding to 10 years). Finally, due to lean burn, NOX emissions are less than 100 ppm with a stable shaft power output in a range of engine speed between 1,200-3,000 rpm [22]. A number of Reciprocating Internal Combustion engine based cogeneration systems suitable for residential and small tertiary sectors are currently available in the market. Honda [23] and Osaka Gas have developed the Ecowill model: a 1 kW electrical and 2.80 kW thermal output cogeneration unit, designed for a single-family applications with an overall energy efficiency of 85%. In the period 2003-2009 about 86,000 units have been sold in Japan with the introduction of a new model on the North American market in 2006 able to supply 1.2 kW of electric power [24]. Tokyo Gas and Aisin (Toyota group) in February 2002 lunched in Japan a micro-CHP [25], available also on the European market since 2006. The model, based on a 3-cylinders-952 cm3 RIC engine, supplies an electric output of 6 kW and 11.7 kW of thermal power, with a total efficiency at full load equal to 85 %. The German manufacturer Senertec [26], that has installed until now over 20,000 units in Europe, produces a cogeneration unit of 5.5 kW electric power: the one-cylinder four-stroke Sachs engine has
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a displacement of 579 cm3 and can be fuelled by natural gas, LPG, fuel oil or biodiesel. Finally Ecopower [27] proposes a micro-CHP, based on Briggs & Stratton 5HP engine, fuelled by natural gas or propane, of 4.7 kW electrical and 12.5 kW thermal outputs for an overall energy efficiency of 85%. The cogenerator can modulate the electric power between 2.0 kW (6.0 kW of thermal power) and 4.7 kW (12.5 kW of thermal power). TDC units Small thermally driven cooling systems with cooling capacities of 30 kW down to a few kW have been developed by a number of European companies and are recently being transferred into the market. The absorption Lithium-bromide – water systems are a well-established cooling technology since many years. Many manufacturers are active in the market for large capacity systems, both for singleeffect and double-effect machines. Recently, small-capacity single-effect systems with cooling powers around 5 to 30 kWc have been developed and are now available on the market. The driving temperatures are around 75-80°C (single stage machines) with the highest COP of around 0.7-0.8, and with the double stage machines that can reach COP of 1.2-1.3 (with a driving temperatures >180°C). Four-five new products have been available in the cooling capacity range < 30 kW (Yazaki WFC-SC5 17.5 kW, Sonnenklima Suninverse 10 kW, EAW 15 kW, Rotartica 4.5 kW, Broad BCT 16 kW, ABAKUS 4.5 kW). The absorption water – ammonia technology is well known and developed for large capacities. The system is characterized by an high pressure system (5-18bar) with a lower COP compared to LiBr systems (around 0.6-0.7). There isn't any risk of crystallization and temperatures below 0°C are possible with higher driving temperatures (>160°C). Direct gas-fired systems are also well established whilst. few small capacity hot-water machines are available or close to market (Pink /SolarNext 12kW, Robur 17kW, AoSol 8kW); several groups are working on new developments (Helioplus 5kW, ITW 10 kW, DAKM 3kW [28]. The LiCl – water absorption system (Thermo Chemical Accumulator TCA) has been developed by the Swedish company ClimateWell. It uses the crystallization effect in order to increase energy density, and through the accumulation of salt crystals it functions as a heat/cold storage. The machine operates intermittently and in order to allow a continuous operation a two-barrel system has been developed. The cooling power is variable in the 2-8kW range, and depends on the cycle progress. The system is available and ClimateWell is the only provider (ClimateWell CW 10). Adsorption technology is less developed than absorption, and two adsorption pairs have been used for adsorption chillers up to now: Silica gel – water and zeolite – water. The intrinsic periodic operation of adsorption chillers requires special attention to the hydraulic integration of these machines. The system is characterized by no moving part, reasonable COP of about 0.5-0.6 and no crystallization risk. Only few large machines are available on the market. In the last few years, new small-capacity machines (7 to 15 kW) have been developed and are available as small series products (SorTech 8&15kW kW, Invensor 7&10kW, SJTU 10kW, ECN 2.5kW). Research is going on in order to improve materials and components. The Desiccant-based evaporative cooling (DEC) is an alternative to conventional vapour compression air conditioning. It is driven largely by thermal energy, uses no ozone layer depleting refrigerant, and improves indoor air quality by providing a drier and more comfortable indoor environment. Most applications to date have been in large buildings with central HVAC systems. Tipically solid systems Desiccant Wheels (DW) and liquid systems (LDS) are on the market, but there are many manufacturers of desiccant wheels and only few providers of liquid desiccant systems.
Application of microtrigeneration in mild climate A promising application of trigeneration is referred to a mild climatic condition such those existing in South Italy, where the authors are investigating the on-site performances of Micro-CCHP under real operating condition [29]. As previously referred, during warm season, there has been an increasing demand of cooling energy generally satisfied by electrically-driven units with an increase of power generation capacity of electric utilities and a summer peak load of electric energy consumption; a solution to mitigate the problem consists in cooling systems fuelled by natural gas. Micro-CCHP with Dessicant Wheel At Sannio University an advanced desiccant air handling unit coupled to a reciprocating internal combustion cogenerator is in a tuning phase. The air handling unit allows, during summer operation
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(outdoor air: temperature = 30°C, humidity ratio = 15 g/kg, relative humidity ≈ 55%), to process 800 m3/h of wet air that achieves the input conditions to the room (inlet air: temperature = 13-19 °C, humidity ratio = 7-11 g/kg). Further HVAC main components are an indirect evaporative cooler and an air to water vapour compression chiller (cooling capacity 8 kW). The MCHP supplies thermal energy (12 kW), recovered by engine cooling and exhaust gas, to the regeneration of the sorption material (silica gel) of the desiccant wheel. An external thermal load allows to simulate hot water requirements. Cogeneration power (6 kW) is used to supply electricity for air handling self consumptions (fans, pumps, …), to drive the electric chiller and finally for the external devices. The MCHP/HVAC-DW system is able to import or to export electricity to the external grid; finally the hybrid HVAC system can also operate in traditional way, interacting with separate “production” systems (electric grid and gas-fired boiler). Micro-CCHP with ThermoChemical Accumulator At the Built Environment Control Laboratory of Seconda Università di Napoli, a microtrigeneration system based on gas fuelled internal combustion engine has been coupled with an Air Cooled Water Chiller, ACWC and a Thermal-Chemical Accumulator; it was set up in Frignano (Lat. 40°59'56"76 N; Long. 14°10'48"00 E), it is a municipality in the Province of Caserta in the Italian region Campania, located about 20 km northwest of Naples and characterized of mild climate with 1101 Degree Days (Internal reference temperature = 20 °C and External reference temperature = 13 °C). During warm season the experimental plant has the opportunity to operate with two different microtrigeneration modes: a micro-CHP/ACWC system and a micro-CHP/TCA system, that are also able to function simultaneously as reported in figure 1 below. Figure 1 Microtrigeneration in summer mode
The system micro-CHP/ACWC is able to supply thermal (heating and hot water, 11.7 kW), electrical (6 kW) and cooling energy (7.5 kW) to a part of a building with offices and laboratories under actual operating conditions. In this operating mode the ACWC is supplied by the electrical output of the micro-CHP (2.5 kW), while the remaining part is supplied to the laboratory uses (up to 3.5 kW). The main reasons that lead to the use of an ACWC system are based on: • the possibility of driving ACWC by electric grid whereas a engine failure occurs or a more convenient energy cost is achievable, • the availability of a system with an high levels of operating modes allows to find the optimum match between the equipment and the end-user load profile ie. to follow the energetic and economic advantages, • a mass production units utilization to reduce the plant first-cost. Nevertheless a great quantity of thermal energy produced by micro-CHP is not used in hot season and in this period the energetic performance of the system is unsatisfactory: for this reason it was taken into account an absorption chiller able to use thermal energy stored in warm season, and the plant has been then completed with an heat storage tank (capacity 1000 lt). In order to supply water at the requested temperature for the TCA operations, a gas fired boiler (efficiency 90%) has been placed in series with the hot storage tank. Because the TCA requests a
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charging temperature not less than 50 °C respect to the external air temperature, the MCHP system has the function to keep a medium water temperature in the heat storage whereas the gas fired boiler ensures the high temperature inlet to charge the TCA. The system will be investigated by the Energetic, Economic and Environmental approach (3-E analysis), by which the performances of system proposed (ie. the Alternative System), are compared to that ones of Conventional energy System, CS, based on separate “production”. In order to perform the abovementioned comparison in terms of energetic balances, the whole system (MCHP/ACWC/TCA) considered, has been equipped with a data measurement and acquisition system as follows: • Mass flow sensor for methane, • Ultrasonic mass flow sensor for water, • Temperature sensors, model TT-227/Pt100, • Watt-meters with measuring range 0-6 kW, • Watt-meters with measuring range 0-10 kW, • Exhaust gas analyzer. The data acquisition systems has been set up with field point I/O system with FP-AI-100 modules to acquire signals by analogical output 4÷20 mA and RTD-124 modules to acquire signals by PT100; the data managment has been finally performed by the LabView software. The system considered is in a start-up phase with some data gathered randomly during summer 2009 and the results are referred to a short acquisition period (2 - 3 days). Figure 2 Power delivered by micro-CHP (MCHP)
Figure 2 reports the thermal power delivered by micro-CHP to the heat storage together with the storage water temperature in a single day acquisition. The storage internal water temperature is measured in two points at different heights and the upper temperature is considered on the graph; from the lines trend it can be possible to observe that the power delivered by micro-CHP rises quickly up to 10 kW few minutes after it was switched on and successively it raise up to the highest value of 11.7 kW after 1/2 hour of functioning; this value is held fairly constant till midday; during the same 1/4 period ( 1 hour) the storage temperature increases of about 8 degrees. After this period the delivered thermal power decreases and the internal storage temperature increases with a slightly sloping. Considering the power deliverd by the MCHP, it can be noted that it presents a sequence of downgrading steps corresponding to the on (lower) and off (upper) operation of the ACWC system. A specific analysis of water storage temperature dynamic is reported in figure 3, where the increasing rate of water temperature has been evaluated for several MCHP operation modes.
Figure 3 Storage temperature increasing rate
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The MCHP run at different electric load (1,5 - 3 - 4,5 kW el) with the corresponding thermal power (horizontal axis) delivered to the storage system; in the last configuration the storage electrical resistance is fed directly by the MCHP, and it can be pointed out that the maximum value obtained for temperature increasing rate is 10.7 °C/h; this is a very challenging topic about the trigeneration system under stuy and its application for summer air conditioning. In general the system should go as soon as possible to its maximum temperature to supply the hot water to the TCA cooling system to get the highest efficiency. For the system under consideration, as reported in the above mentioned figures, it's interesting to observe that water temperature is not high enough to be efficiently used in the TCA and about 1 hour is necessary to raise the water temperature of ten degrees. To this aim a domestic boiler it has been necessary to improve TCA inlet temperature; an obviuos development of the plant will consist in using a suitable solar collector to push the water temperature up to 90 - 95 °C. Figure 4 reports, for the same period, the ACWC power lines with values referred to the cooling capacity and the corresponding electric request; the system is characterized by frequent on-off operation with a subsequent temperatures fluctuation at the inlet and outlet of the fan-coils hydronic circuit as reported in figure 5. From the acquired data it can be pointed out that the large commercially available cooling unit considered has a very low cost but very poor performances in term of COP (range 1,5 ÷ 2) and a more efficient unit, equipped with the most advanced technology like multi sensors electronic inverter, is therefore required for a better performance. Furthermore, it clearly appears that a water storage system is necessary for the cooling circuit, to set a nearly constant temperature for the inlet and outlet fan-coils circuit. Figure 4 ACWC cooling power
Figure 5 Fan-coils circuit inlet and outlet temperature in cooling mode
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Finally the system proposed has been compared, in terms of Primary Energy Saving (PES), to a Conventional System (CS) and to the Best Available Technology (BAT) system [30]. These systems are based on separate “production”, i.e. a Power Plant, PP, connected to the electric grid and a natural gas-fired Boiler (figure 6). The efficiencies values set for the comparison are for CS ηpp = 0,46 - ηB = 0,85, and for BAT ηpp = 0,515 - ηB = 0,95; regarding the system proposed, due to the fact that TCA was in start up phase and hence few data were collected, a COP value of 0.65 was set for the simulation considering the water temperature available from heat storage and the TCA performances reported from manufacturer [31]. Figure 6 Primary Energy Saving comparisons
The PES has been evaluated from acquired data and an interpolating curve has been overlapped to the scattered points. The proposed micro-CCHP system has a better performance with respect to the Conventional System during all day long with an upper limit of 10%, whilst the comparison to the BAT system shows only a poor increasing for the PES in a short period. It's interesting to observe that the graph has a similar trend to that reported in figure 2, with a PES decreasing during the day. This is due to the lower heat transfer efficiency within the storage tank. This limit together with the TCA coefficient of performances seems to greatly affect the trigeneration energetic performances.
Conclusions In this paper a framework about the current status on microtrigeneration applications has been reported considering political and legislative aspects, as far as several projects developed and supported for utilization in the building sector. The technological aspect has considered the current status of several micro-CHP technologies that are available or close to market, with a large research activities in the field of micro-CHP systems of new technologies (Stirling, Fuel Cells, gas turbine, Organic Rankine Cycle); furthermore some small capacity TDCs are available in small series products and it's hoped that more systems will be shortly developed in the frame of solar cooling projects. Two case studies of microtrigeneration applications in non residential sector are reported with some performance measurements accomplished on microCCHP-TCA coupling. A first level of this analysis has been focused to the MCHP system, and it revealed some intrinsic limits mainly related to waste thermal heat recovered from engine to the storage tank: the heat transfer
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efficiency strongly decreases during the stationary system operations and the maximum water temperature is not suitable for an efficient utilization in a TDC system. Practical experience is then necessary for the systems that shows operability but need to be optimised. In the research follow-on the aim is to provide a more efficient components (ie. ACWC equipped with inverter and/or solar collectors) and find the best operating conditions not only with regards the optimization of energetic performance of the trigeneration system, but also on the optimization between the system and the user load profile to define several operating strategy and their impact on system optimum performance. Acknowledgments This work has been supported by Italian research project PRIN 2007 “Criteria and methodologies for the optimization of small/medium scale polygeneration systems”. References [1]
http://www.polygeneration.org/
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D-PLOY Deploying Large-Scale Polygeneration in Industry Technical Report Workpackage 2 HEAT LOADS AND POLYGENERATION APPLICATIONS Chemical, food, paper and refinery sectors, August 2008.
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Aprile M. The market potential of micro-CHCP, POLYSMART Workshop, January 2010.
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POLYSMART Polygeneration in Europe, Technical report, 2008.
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D-PLOY Report D3.1 "European Policy and Legislation affecting Polygeneration", 2007.
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European Parliament, Directive 2004/8/EC of the European Parliament and of the Council on the promotion of cogeneration based on a useful heat demand in the internal energy market and amending Directive 92/42/EEC. Official Journal L 52, 21/2/2004, pp. 50–60.
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European Parliament, Directive 2003/54/ec of the European Parliament and of the Council concerning common rules for the internal market in electricity and repealing Directive 96/92/EC. Official Journal L 176, 15/7/2003, pp. 37–55.
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European Parliament, Directive 2003/55/EC of the European Parliament and of the Council concerning common rules for the internal market in natural gas and repealing Directive 98/30/EC. Official Journal L 176 , 15/07/2003, pp. 57 - 78
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European Parliament, Directive 2003/96/EC of the European Parliament and of the Council restructuring the Community framework for the taxation of energy products and electricity. Official Journal L 1283, 31/10/2003, pp. 51 - 70.
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European Parliament, Directive 2001/77/EC of the European Parliament and of the Council on the promotion of electricity produced from renewable energy sources in the internal electricity market. Official Journal L 283, 27/10/2001, pp. 33–40.
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White Paper on District Heating and District Cooling Solutions in an Environmental Perspective, An industry information paper prepared by COWI, Danfoss, Grundfos and LOGSTOR, September 2007
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Entchev, E., Gusdorf, J., Swinton, M., Bell, M., Szadkowski, F., Kalbfleish, W. and Marchand, R. Micro-cogeneration technology assessment for housing technology, Energy and Buildings, 36(9), 2004, pp. 925–931.
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Knight, I. and Ugursal, I., Residential cogeneration systems: technologies,Report of IEA Annex 42 Subtask A, 2005.
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Dentice d'Accadia, M., Sasso, M. and Sibilio, S. Field test of a small-size gas engine driven heat pump in an office application: first results. International Journal of Ambient Energy, 16, 1995, pp. 183-191.
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Hawkes, A.D., and Leach, M.A. On policy instruments for support of micro combined heat and power. Energy Policy, 36 (8), 2008, pp. 2963– 2972.
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Jakob U. Nuove soluzioni nell’ambito del raffreddamento solare, Proc of the 2nd Energy Forum – Architettura & Edilizia Solare (Brixen, South Tyrol, 2007).
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Possidente R., Roselli C., Sasso M. and Sibilio S. Microcogeneration and polygeneration for building in mild climate Proc First International Conference and workshop on MicroCogeneration Technologies and Applications (Ottawa, Canada, May 2008)
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Roselli C., Sasso M., Sibilio S. Experimental analysis of different small scale combined cooling, heating and power systems based on a natural gasfired reciprocating internal combustion engine Proc. ASME-ATI-UIT 2010 Conference on Thermal and Environmental Issues in Energy Systems (Sorrento Italy, May 2010)
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Bales C. and Nordlander S. TCA Evaluation Lab Measurements, Modelling and System Simulations, Report Solar Energy Research Center, ISSN 1401 - 7555, December 2005
a review of the current
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IEECB'10 Success Examples & Retrofits
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Energy Efficiency in Historic Buildings, the case study of the National Theatre of Rhodes, Greece and of the Zena Castle, Italy Maria Kikira a, Elena Gigliarelli b a Architect, Department of Buildings, Division of Energy Efficiency, Centre for Renewable Energy Sources and Saving-CRES, Greece and researcher, University College London Energy Institute, UK b Architect, CNR - ITABC Institute of Technology Applied to Cultural Heritage, Italy
Abstract The potential of energy saving measures in historic buildings is of great interest, due to the increased building stock in European level, the particularities in their architectural form, typology and age of construction, the energy efficient initial design and their specific use and operation. Museums, theatres, churches, as well as offices, universities and hotels, are accommodated in historic buildings. Even if historic buildings are excluded from the Energy Performance of Buildings Directive 2002/91/EC, the need for revitalising and reducing energy consumption in such constructions is rather a challenge towards sustainability and CO2 emissions cut. The aim of this paper is to examine the potential of energy efficiency in historic buildings and communities, presenting the particularities, barriers and challenges in this context. Recent results from an ongoing European programme titled ‘SECHURBA’ are assessed, highlighting the work of seven countries, in relation to sustainability prospects of historic buildings and communities. A study of an example of historic excellence such as the National Theatre of Rhodes in Greece and the Castle of Zena near Piacenza in Italy is presented. The energy audit and energy efficiency study reveal the quality of the design and construction of such buildings and underline the prospective of envelope and cooling system improvement, while revitalising their use and restoring their architectural characteristics. Keywords: cultural heritage, building envelope, energy audit, bioclimatic principles, saving potential
Introduction to Historic Buildings and Communities European and national targets and measures towards energy efficiency and integration of renewable energy sources are firm with limited time tolerance. Sustainability and environmental awareness set as priorities into the construction industry, focusing on existing high consuming building stock. Historic buildings and communities urge to follow and even lead these initiatives, even if the challenges and barriers often predominate these goals. The establishment of a synergy between the cultural heritage protection and the sustainability observance consist the aim of the issues raised in this study. Designing and retrofitting historic buildings requires a holistic approach, considering architectural, cultural, energy and economic viability. This approach differs from the traditional design/build process, as it’s necessary to examine the integration and interrelation of all building components and systems and the merging of old and modern technologies. The Directive on the Energy Performance of Buildings (Directive 2002/91/EC) [1] and its recast [2] introduce incentives and obligations for public and private sector to save energy and reduce running costs. However, historic buildings are excluded from these commitments as stated in the recast: “Article 4 - Setting of energy performance requirements: Member States may decide not to set or apply the requirements reffered to in paragraph 1 for the following categories of buildings: buildings and monuments officially protected as part of a designated environment or because of their special architectural or historic merit, where compliance with the requirements would unacceptably alter their character or appearance;” [2]. Apparently, this does not mean that historic buildings could consume energy beyond any threshold. The enrichment of knowledge and scientific research into the sustainability and energy efficiency of historic buildings is important, considering their vast potential all
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over Europe. Even so, the reuse and rehabilitation of a historic (or not) building consist an energy efficiency measure itself. SECHURBA linking European countries SECHURBA (Sustainable Energy Communities in Historic URban Areas) [3] is a European project funded by Intelligent Energy for Europe, with a consortium of 13 organisations from 7 EU member countries. It aims to study barriers and prospects of various historic urban communities and buildings with diversity in local and national cultural framework. A critical target is to develop Historic Community Climate Change Strategies and route maps for intervening in such culturally sensitive areas. Initial findings from this project are presented in this paper, addressing common characteristics and also individualities of such case studies. Historic buildings characteristics The following characteristics of historic buildings could be indicatively addressed: • Architectural and historical excellence. • Significantly high heights / large volumes (+) efficient cooling performance, (-) high heating demand. • Increased thermal mass, increased wall thickness, solid walls with no insulation (+) control of internal temperatures, smooth temperature fluctuation, qualitative envelope performance. • Controlled and limited openings (window to wall ration often less than 20%)…while contemporary design move towards light and total transparency (+) control sun and light (-) limit passive heating potential. • Recessed windows and openings (+) Self-shading, moderate overheating. • External overhangs, patio, terraces, trees, internal courtyards, roof openings, solar and ventilation chimneys (+) Surrounding space cooling and ventilation, improved microclimate. • Earth and light colours (+) Environmental and climate deference. • Natural lighting and ventilation (+) Human satisfaction and expectation success standards.
Fig. 1: Photos…thermal mass, colours, openings, dignity of historic buildings. (Source: [4]) The above characteristics could be easily considered as bioclimatic: design and build according to the local climate. Therefore, historic buildings embody bioclimatic principles, and as soon as they are exploited efficiently and not vitiated through ages, revitalization and sustainability are realistically achievable. However, “Having a listed building is like a curse!”, an owner of a historic building reported during a SECHURBA project workshop. The procedures of intervening in such buildings often constraint any willingness to conform the architectural and cultural heritage into the contemporary demands. Energy efficiency building interventions have been widely developed by the research and market community, such as the reduction of energy demand and thermal losses through envelope and installations improvement, the integration of renewable energy sources, the awareness rising of occupants, etc [4]. However, interventions in historic buildings -except of architectural preservation purposes- require a holistic study in order to address potential risks such as: moisture and condensation occurrence, chemical incompatibility of old with new construction materials, failures due
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to limited construction knowledge on restoration applications with sustainable technologies. In addition to that, various interventions in time that have been possessed to a building structure and have never been recorded or monitored, constrain a thorough picture of actual building elements. Historic Community, not just like the others Projecting this potential into perspective, historic communities –and especially in urban city centres – address several particularities and challenges such as: § § § § § § § §
High number of visitors and seasonal population (peaks in services, infrastructure transportation, networks). Multi-cultural character, challenge to accommodate diversities and individualities. Limitations to integrate renewable energy sources. Past and future cohabitation, alternation or retention of character and cultural profile. Development versus functionality – often pedestrianisation implemented in a historic centre cause problems of accessing to services and shops within this area. Residents versus visitors, trends of changing uses from residential to commercial. High cost of living, increased value in historic urban areas. High tourism attraction (potential for demonstration and awareness activities and projects).
For example, a community case study in Athens city centre sized 46ha, has a number of 260 listed buildings and a conservation area of 4ha. However, it is recorded that most of the buildings are deserted due to the poor legislative and financial incentives and to the high tourism density and immigrant population. Therefore, except of sustainability viability, the social, economic and security priorities are high in the agenda of the municipal area reformation plan.
Fig. 2: Athens case study area showing listed buildings (green spots) and conservation area (yellow area). (Source: [3]) How could historic communities contribute to sustainability and environmental protection? An integrated approach need to be followed through targeted interventions in: Environment, Society, Culture and Economy. The key role is the local authority and society awareness, as well as their participation and commitment. NATIONAL THEATRE OF RHODES, GREECE Introduction to the history National Theatre of Rhodes (NTR) was designed by the architect • rmando Bernabiti and built during Italian possession in 1930’s. It was used as a lyrical theatre; it has a rectangular layout and could be characterized as a “double shell” construction with the auxiliary spaces in the perimeter, working as
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buffer zones between the stage and the surrounding areas. The building was subjected to serious interventions during the period 1972-77 when air conditioning system was installed, altering few architectural and bioclimatic building elements, such as sealing of openings and demolition of certain internal partitions (for the mechanical system). However, these interventions were limited to the internal of the building and did not extend to the external appearance and form.
Fig. 3: External images of the building – Left: East façade, main entrance – Right: South facade. (Source: Division of Preservation of the Medieval City of the Municipality of Rhodes) NTR could be considered as a building monument to the island due to its historical significance, to its location within the city and its size, fact that increases (or constraints) the challenge and the prospective for future revitalisation interventions, as being out for operation since 2004. Thus, the Municipality of Rhodes, division of Preservation of the Medieval City of Rhodes undertook the initiative to re-operate this building, having a holistic approach towards the refurbishment process by adding the value of integrating energy performance principles. In cooperation with CRES, an energy study has been developed [6] in order to assess the building’s energy performance and bioclimatic elements, evaluate certain energy efficiency measures and examine the possibility of PV integration. The proposed energy saving interventions were mostly based on the findings from the energy audit and the thermal simulation parametrical analysis, integrating contemporary and new technologies and decreasing the building’s operation cost (for heating, cooling and lighting). Existing condition The building structure has high thermal mass of 35 – 45cm reinforced concrete and of 27,5cm brick walls, with 4,5cm external coating of imitating stone surface and plaster coating in the internal part of the walls. The form and shape of the windows and frames define a historic building’s appearance with recessed windows to 40-60-95cm (except of the curved transparent surfaces) which result to a summer shading of 60-100%. The limited proportion of window to wall ratio stands as in most historic buildings with 7% in west, 14% east, 16% north and 20% in south building façade. Windows are single glazing with wooden frames, while the curved surfaces are alabaster with wooden frames. Certain openings in vertical surfaces and roof have been sealed during 1970’s interventions, limiting the natural lighting and ventilation dynamic. Large heights and volumes are recorded in most spaces, increasing the demand for heating and decreasing the demand for cooling. A characteristic of the building is the “double envelope” layout as the main stage forms the core of the building, surrounded by secondary and auxiliary spaces (greenrooms, circulation areas, offices, exhibition areas, etc). Energy Audit findings From the thermographic analysis of the building the following findings could be summarized [7]: § The construction elements of the building envelope have few damages from the plaster collapse and high humidity concentration in the walls, especially in the higher levels of the building. § Moisture and condensation problems have been identified causing thermal bridging effect and further damage to the construction elements. § High thermal losses through the openings are evident, especially from the single glass surfaces.
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§ §
Short run interventions in the structure of the building are needed in order to avoid corrosion of the reinforcement elements. The quality of overall construction is very high with minimum thermal bridging effect, despite its age.
Thermographic analysis is presented below for the three main building façades.
23,9°C
SP02 SP01 SP07 SP06 SP04
SP05
SP03
15,3°C
Spot
Temperature
SP01
17,0°C
SP02
18,7°C
SP03
16,6°C
SP04
17,2°C
SP05
17,5°C
SP06
16,4°C
SP07
17,6°C
Fig. 4: Thermographic analysis of alabaster surfaces – north façade. (Source: [6,7])
21.5°C SP01 SP02
SP03
SP06 SP07
20
18
Spot
Temperature
SP01
16,5°C
SP02
19,4°C
SP03
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17,5°C
SP05
16,6°C
SP06
18,0°C
SP07
15,2°C
16
SP04 SP05
14 13.0°C
Fig. 5: Thermographic analysis of top level – south façade. (Source: [6,7])
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SP01 SP02
18.7°C
SP03
SP06
Spot
Temperature
SP01
13,8°C
SP02
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SP03
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15,2°C
18
16 SP09
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SP07SP08
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10.1°C
Fig. 6: Thermographic analysis of east façade above main entrance – single glazed openings. (Source: [6,7]) Envelope Thermal Performance and analysis An extended simulation study followed the thermographic analysis in order to assess the impact of building envelope improvement as well as of the re-operation of natural ventilation. Different scenarios have been studied in order to identify the potential energy saving from: the improvement of the envelope performance through insulation and windows replacement and from the restoration and re-operation of the horizontal and vertical openings for natural night ventilation purposes. It is apparent that the openings operate strategically for the natural ventilation and the decrease of the cooling demand, as they facilitate the warm air exhaust from the higher levels of the building (Fig. 7).
Fig. 7: Air circulation through vertical and horizontal openings. Left picture: sealed skylights from interventions in 1970s, Right picture: sealed ceiling openings after interventions (Source: [6]) The building was separated in 26 thermal zones according to their profile and use. The stage represents the largest volume followed by the orchestra area, the commuting spaces and the greenrooms. TRNSYS simulation software was used for the analysis with set point temperatures to 26oC for cooling and 20oC for heating. Regarding the existing performance of the building, the study resulted to 31,58kWh/m2 yearly demand for heating and 32,93kWh/m2 for cooling. Examining the scenario that the building does not operate 2 during July and August, the cooling demand decreases to 11,52kWh/m . The condition of the building is considered as poor, however the overall energy performance is satisfactory due to the ‘double shell’ construction, the envelope quality, the positioning of the openings and in general the bioclimatic
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design of the building. The analytical findings from the energy analysis are the following. Proposed Intervention
Energy saving
Heating demand
Cooling demand
Examined for 12-month use Insulation placement to the external walls (internal) and roof 39,41 % 21,55 kWh/m2 (external) Replacement of windows from single to double glazing and improved frames
2,95%
Replacement of windows from single to improved double glazing and frames
4,29%
17,54 kWh/m2
Insulation placement and replacement of windows with improved 45,98% double glazing As above, adding natural ventilation for the heating period, re- 49,43% operating the vertical and horizontal openings (from 23:00 to 6:00)
18,17kWh/m2
14,45kWh/m2
Table 1: Energy saving potential of different improvement scenaria (Source: [6,7]) The placement of the insulation internally or externally does not affect significantly the thermal inertia of the building, mainly due to the high quality construction and thermal capacity of the internal walls (especially perimetric of the stage). For the retention of the internal dimensions of the spaces (perimeter spaces are rather shallow) and due to the fact that external finishing would be replaced during the refurbishment process, external insulation has been decided in cooperation with Division of Preservation of the Medieval City, retaining the aesthetics and architecture of the building. The graph below summarizes the results in energy demand for heating and cooling before and after the proposed interventions. It is evident that most significant impact to the building’s energy performance is recorded in the peak winter and summer months due to the insulation addition and the natural ventilation techniques respectively. The replacement of the windows might have a limited impact for the building overall (due to the limited percentage of such surfaces) however for the thermal zones in the perimeter of the façade, the impact is significantly higher. Energy Demand for Heating and Cooling Existing Condition
Im proved scenario
12 10
10,5
7,6
kWh/m2
8 6
10,9
9,7
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Mar
1,4 0,8 0,4
0,8 0,6 0,2
Apr
May
Jun
Jul
Aug
Sept
Oct
1,5 0,5
Nov
Dec
Fig. 8: Building total energy demand for heating and cooling before and after the proposed interventions (Source: [6]) The energy study included a day lighting analysis which is not explored in this paper, as well as other proposed intervention in the building electromechanical and management systems. Integration of Photovoltaic Panels
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The possibility to integrate photovoltaic panels in the roof of the building was also studied. Being a historic building, special attention was allocated to the positioning of the panels for architectural and aesthetic purposes. The option of roof mounted, following the roof inclination (3-5o), facing south and placed 10cm away from the final roof surface for ventilation purposes, was decided. Based on available area, economic viability and historical preservation aesthetics, a system of 100m2 was proposed, with a capacity of 13,6 kWp and estimated yearly energy production of 18 MWh. Special attention need to be ensured during the placement of the panels so as not to damage the roof structure and insulation layer. For demonstration and education purposes to the public and visitors, an online screen system would present real time PV energy production data within a designated area inside the theatre spaces. CASTLE OF ZENA, ITALY Another case study is the restoration project of Zena castle, for a functional recovery of this monument as a congress and business centre. The aim is to respect the integrity and authenticity of the monument, as well as its sustainability, comfort and ‘livability’ with the use of technological solutions for energy saving and renewable energy systems. A research study has been progressed in SECHURBA project with the objective to explore the links between utilization and conservation in monuments and to develop evaluation models for energy adaptation in historical buildings. Thus, a multi-criteria analysis decision making tool is under development and it aims to assist the feasibility and compatibility process of new applying energy saving systems, as well as of alternative energy sources in ancient buildings and historical centers. Multi-Criteria Analysis (MCA) The Tool has been developed in order to evaluate the potential for Renewable Energy Source (RES) and Rational Use of Energy (RUE) integration at two levels: first evaluating energy saving options against physical characteristics, secondly a Multi-Criteria Analysis (MCA) to address aesthetic and historic features, energy saving systems, financial and administrative frameworks. Environmental and technical indicators have been introduced, together with economic and sustainability benchmarks. The concept of the design tool is presented in the figure below.
Fig. 9: The analytic phase of the Multicriteria Analysis technique, a decision model that helps to identify different solutions for energy rehabilitation of historical buildings. Multicriteria approach was tested at Zena Castle SECHURBA case study, a medieval fortification located in alluvial plains of the Po river, which turned into a country residence in the mid 1700s. The
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aim was to choose the most sustainable solutions in such example of historic excellence. Energy assessment findings An energy assessment antedated the tool application, in terms of restoring its architectural characteristics, improving its construction and revitalizing its use and operation. Before proceeding with the sustainable energy review, an integrated preliminary survey on the historical, physical and architectural profile regarding the monument has been completed. The study was carried out by ITABC with an interdisciplinary, holistic approach for sustainable restoration. An energy assessment was done as well as an infrared thermographic analysis, which reveals thermal irregularities on the building envelope. The design team involved into the technological upgrade of the castle aimed to combine high tech elements in the pre-existing installations. Emphasis was given to the innovative aspects of energy production and use of renewable sources, establishing also a low cost efficient energy solution. The proposed interventions for technological and energy efficiency improvement mainly consists of: 1. Increasing the sealing and insulation of the building envelope (exterior walls, roofs and ground floors, shutters, doors and windows), therefore reducing the heating requirements. 2. Reusing some of the attic areas that meet the necessary sanitary and hygienic requirements for occupancy as living quarters, for optimum recovery of space. 3. Restoring accessibility, functionality and structural reinforcement to the eastern wing that was abandoned after the collapse of the intermediate floors (Fig. 10). 4. Recovery of the basement areas from both conservation and functional standpoint. 5. Design of an innovative energy production system for the entire architectural complex, supported by the use of renewable sources. Additionally, reduce energy consumption for cooling during the summer and heating during the winter and improve the hot water system and lighting of the indoor and outdoor areas. The possible solutions for thermal insulation of the perimeter walls are only on the interior side, since the exterior envelope is constructed with fine mortar and visible brick, and there is no cavity in the walls. The ample thickness of the walls nevertheless provides an adequate thermal conductivity (U value). The interior insulation was adopted in two historic “service” areas of the castle which are therefore free of any frescoes, wall decorations or fine flooring. In these areas, a ventilation space with recycled plastic cement casings will be created for the ground floors, and the walls will be internally insulated with wool and wooden fibre panels covered with mortar. Within these areas, the design of a radiant heat and air conditioning system powered by a geothermal pump is proposed, using the groundwater from the several existing wells on the property. The precarious condition of the load bearing trusses and the roof covering require the disassembly of the roof, allowing the creation of an insulated and ventilated space for maximum comfort and durability of the structure (Fig 11).
Fig. 10 (left): The 3D model created for the functional and energy restoration of the eastern wing of the castle. Fig. 11 (right): Solution adopted for the thermal insulation of the roof. In order to reduce high thermal losses from the envelope, insulation and sealing of the existing doors and window frames is proposed, by replacing the windows with triple-layer low-E glass (with Argon
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gas between the layers). In regards to the systems integration, several options were analyzed and a trigeneration system was selected, which allows autonomous production of electric power and water to water heat pumps by using groundwater. CONCLUSIONS AND FURTHER RESEARCH Historic buildings and communities potential and challenges in terms of energy efficiency and renewable energy sources integration is indisputably interesting and valuable to the sustainability as well to cultural heritage protection and revitalization. The scope is to identify such interventions that preserve cultural heritage, enhance aesthetical and architectural potential, and ensure functionality, energy efficiency and high thermal performance. SECHURBA project and the above described case studies aspire to consist an exemplar example of revitalizing historic communities and buildings though an holistic and scientific approach. In the case of National Theatre of Rhodes, the energy study revealed a high potential of energy saving for heating and cooling load, decreasing energy demand almost to the half. Therefore, preserving the initial architectural excellence, detracting all later arbitrarily interventions throughout the time and introducing an integrated approach to energy restoration is an important asset. Further studies need to be done in order to identify such parameters that will encourage European and national legislations to include and motivate these target groups into sustainability and high standard environmental performance. There is a need for targeted demonstration projects -and not only scattered case studies across Europe-, legislation initiatives, policy making and local authorities motivation, systematic research, monitoring and educational projects, increased competitiveness among historic and other communities and knowledge exchange and enrichment. Buildings need to revitalise within their lifetime, to provide high standard indoor environmental conditions, to consume less energy and operate for less…Respectively, historic communities need to efficiently exploit their energy, economic and cultural prospects through a balance of undergoing development. “..Although people value the historic environment, this does not represent resistance to change..” [8]. References [1] Directive 2002/91/EC of the European Parliament and the Council of 16 December 2002 on the energy performance of buildings. Official Journal of the European Communities (4.1.2003). [2] EPBD Recast, http://www.eceee.org/buildings/EPBD_Recast/ [3] SECHURBA: Sustainable Energy Communities in Historic Urban Areas, Intelligent Energy for Europe Sustainable Energy Communities action, website: www.sechurba.eu, 01/09/200830/04/2011. [4]
Energy conservation in traditional buildings http://www.helm.org.uk/upload/pdf/EnergyConservation.pdf
(English
Heritage),
[5] Photos taken by the author, Sifnos island – Greece, Petra – Jordan, Black sea – Jordan, Rhodes island – Greece. [6] Kikira, M., Lambropoulou, L., Markogiannakis, G., Alexandri, E., Tselepis, E., (Athens, June 2008). Energy study for the renovation and rehabilitation of the National Theatre of Rhodes, Centre for Renewable Energy Sources in cooperation with the Municipality of Rhodes. [7] Kikira, M., Alexandri, E., Lambroulou, L., Tselepis, E., A. Paraskevopoulou, Magos, K. (Cyprus, 26-28 March 2009), Energy saving measures in the historic building of the National Theatre for th Rhodes, article in the 9 Conference of the Institute for Solar Technology. [8] English Heritage, Part 1: Power of Place, Birmingham, page 4 http://www.english-heritage.org.uk/upload/pdf/power_of_place_11.pdf
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What Really Makes Buildings Efficient: Energy High Rise Project
Results from the Low
Paul Bannister1, Chris Bloomfield1, Michael Porter1, Sue Salmon2, Robert Mitchel2, Robert Quinn3 2 3 Exergy Australia, The Warren Centre, University of Sydney, National Project Consultants
1
Abstract The Low Energy High Rise Project has undertaken a comprehensive statistical analysis for Australian office buildings of the relationship between achieved energy and water efficiency a wide range of technical features and management practices. For some years, Australian office buildings have had available energy and water performance ratings, through NABERS (National Australian Built Environment Rating System), formerly ABGR (Australian Building Greenhouse Rating). These ratings provide auditable demonstration of the buildings achieved energy and water efficiency that allows direct comparison between different buildings. The presence of this rating tool in the Australian market for close to 10 years provides an unrivalled level of information and disclosure of real world building performance. In a world-first result, the study has been able to demonstrate clear statistical evidence that certain factors really do correlate with efficient outcomes, and to quantify the impacts. Key factors that correlate with improved performance include: • New buildings, and for temperate climates, those with air side economy cycles perform better; • Improving the technology of buildings increases the variance in the buildings performance; • Buildings perform better when managers undertake regular incremental upgrades and focus on eliminating older and unserviceable technologies; • Buildings that report their performance to their tenants or the public perform better; • Buildings that perform better provide operators and maintenance staff with reason to care about the performance of their building, such as through incentives; • Buildings that perform better have strong management leadership with regards to efficiency, share common objectives and agendas for efficiency throughout the management chain and retain efficiency savings in budgets; • Buildings perform better when the staff are given training in efficiency and are building managers who are not overly conservative with respect to efficiency technologies This paper provides a review of the project, presents the derivation of key results and discusses the next steps in the study. Introduction The technical issues associated with energy efficiency in the commercial office sector are relatively well established, but widespread application of these remains elusive. The existence of market failures in the application of energy efficiency in the sector is similarly well understood, and there have been many studies documenting such barriers. The Low Energy High Rise (LEHR) project was established to seek methods by which a greater uptake of energy and water efficiency can be achieved. Integral to the approach of the project was the decision not to focus on the market failures and barriers but rather to ask what was different about those organisations or buildings apparently succeeding in the face of these problems. Central to this project was the investigation of the correlations between building technology, building management, and building performance. In essence, the question being asked was whether there are identifiable traits associated with buildings that are more efficient. This paper presents results from this statistical investigation. However, rather than report the dry details of the study and the thousands of statistical tests undertaken, the format of this paper is to propose a number of action-oriented findings and demonstrate the underlying statistics supporting these findings. In this manner, the findings are more practical and accessible than would be the case for a more academically focused paper.
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1.
Measurement of energy and water efficiency - NABERS
For over 10 years, Australian office buildings have had available energy performance ratings through the National Australian Built Environment Rating System Energy rating (formerly known as ABGR, or the Australian Building Greenhouse Rating)[1]. For approximately 5 years, NABERS water ratings have been available, to assess the water efficiency of office buildings. NABERS ratings have become the industry accepted metric for assessing operational building performance in Australia[2]. Because of the level of acceptance, market performance, transparency and accountability of ratings, they have been used as the basis for this study. NABERS ratings assess actual performance over 12 months, through metered energy or water bills. Consumption is normalized against the building’s operational requirements, such as the building’s area, hours of occupancy tenants, climate, et cetera. NABERS ratings are audited, and have become of substantial market value within Australia, with over 50% of Australian office floor area having been rated under the program[3]. The uptake of NABERS ratings has rapidly been increasing, with the mandatory disclosure of NABERS energy ratings for office buildings proposed in legislation in 2010[4]. NABERS ratings are presented in stars, on a one to five star scale, with half star increments. 2.5 stars has been set to the average efficiency of buildings in Australia, with better buildings having a higher rating. An improvement of one star corresponds to a reduction in greenhouse gas emissions, or water consumption by approximately 25%. Further background on the NABERS program is available from the NABERS webpage at www.nabers.com.au. NABERS is administered by the New South Wales Department of Environment, Climate Change and Water.
2.
The Statistical Study Methodology
At the heart of this study lies a large and complex survey. Indeed, three separate surveys were used: • A base building survey, covering the technologies and management of the building; • A tenant survey, covering the interactions between the base building and the tenant; • A manager’s survey, covering the knowledge, attitudes, authorities and responsibilities of the building, property and asset managers associated with the building. Well over a hundred questions were covered within these surveys, which were distributed to 189 buildings, 188 tenancies and 296 managers. Satisfactory responses were received from 127 buildings, 102 tenancies and 173 managers. However the need to cross correlate base building data with tenancy and manager data meant that the cross-survey analyses were based on 67 base building and tenancy sets, 93 base building and manager sets and 53 base building, tenancy and manager sets. As this study focused on larger buildings, the sample represents approximately 20% of the net lettable area of office space in Australia. The hypothesis testing processes were based around statistical testing of the following types of proposition: • Do the answers to an individual survey question correlate with the NABERS Energy or Water rating? • Do buildings with NABERS Energy or Water ratings of 3 or above have statistically significant different responses to an individual question than those with ratings below 3 stars? • Do the answers to logically related aggregates of individual survey questions correlate with the NABERS Energy or Water rating? • Do buildings with NABERS Energy or Water ratings of 3 or above have statistically significant different responses to logically related aggregates of individual survey questions than those with ratings below 3 stars? In addition, some information was derived directly from manager’s responses to what they considered to be barriers or facilitators for efficiency decisions.
3.
The Data Sample
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The resultant data sample was tested for a number of factors to establish to what extent biases existed. The following factors were noted: • The sample was biased to high quality buildings, with the majority being classed by the Property Council of Australia as being premium, A and B grade buildings (the top three grades of office accommodation), with lower grades being largely absent from the sample; • The state/city distribution was a reasonable reflection of the national distribution of office buildings. Note however that the majority of office buildings in Australia are located in the relatively temperate south, rather than the arid or tropical northern areas, which results in a climate bias; • The sample was biased towards larger buildings, with sub 10,000m2 buildings being absent from the sample. • The sample had an average NABERS Energy Base Building performance of 2.87 stars and a median performance of 3.25 stars. NABERS is based upon a much larger sample of buildings, with 2.5 stars representing median performance across the national building stock.. • The sample has an average NABERS Energy Whole Building performance of 2.96 stars and a median performance of 2.91 stars. Again both figures are marginally better than population average, of 2.5 stars across the total building stock. These factors indicate that the statistical results can only be considered appropriate for the upper end of the market. However, in many cases it is reasonable to postulate extrapolations to the broader market and indeed to some other building types.
4.
Basic results
From the hundreds of tests and hypotheses undertaken, the following results were identified. Table 1. Statistically significant relationships identified NABERS Energy Impact (percentage improvement in efficiency) 0.6 stars (15%)
Measure Summary
Building technology
1.4 stars (36%)
Management
1.3 stars (34%)
Buildings with current good practice facade and services technology perform better Buildings where management is at least partially insourced perform better Buildings where building, asset and portfolio manager all feel able to affect efficiency perform better Buildings perform better when there is support for efficiency from building owners Buildings perform better when energy efficiency savings can be retained in the building budget Buildings that disclose their NABERS performance to tenants perform better Buildings that provide efficiency penalties/incentives to maintenance contractors perform better. Buildings where there is an efficiency training program perform better Buildings where the manager reports a higher level of energy efficiency knowledge perform better Buildings where the building manager is conservative with respect to new technologies perform poorer Buildings where incremental investments have been made in efficiency perform better than those where no such investment has occurred.
Measure
Air side Economy Cycle
0.9 stars (23%) Weak Weak Disclosure
0.5 stars (13%)
Incentives and Penalties Training and skills
0.4 stars (10%) 0.5 stars (13%) 1.3 stars (34%) Weak
Incremental Improvement
0.6 stars (15%)
Buildings with Economy cycles outperform those without
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Note: Due to cross correlation between factors, the individual results in Table are not cumulative. These results provide an insight into factors affecting building performance but are of limited assistance in informing actions and decisions relating to efficiency. As a result, a range of actionoriented findings have been developed based on these key findings combined with some of the other results from the study and a degree of extrapolation.
5.
What Really Makes Buildings Efficient?
5.1.
Finding 1. Most building types can be operated at up to 3.5 stars (consumption is 74% of average) even if the underlying technology isn’t particularly efficient. VAV buildings are capable of both the best and the worst performance, probably due to their reliance on control to produce efficient operation.
The basis of this finding is illustrated clearly in Figure 1, Figure 2 and Figure 3. In these figures the dot represents sample mean, with statistical error bars as marked; the solid box represents the 25th and 75th percentiles and the dotted box the 10th and 90th percentiles. In Figure 1 it can be seen that there is no significant difference between the different PCA grades within the sample, and that furthermore all groups have both high and low performing examples. This supports building “quality” being independent from building performance. However, it should be noted that the PCA grades relate to the services supplied to the tenants, rather than the technology used to supply the services. In Figure 2, it can be seen that while more recent buildings definitely perform better on average, all age groups have examples of high performing buildings. In Figure 3, it can be seen that VAV buildings show a wide range of performance from excellent to very poor. Other building types tend to be less diverse, perhaps reflecting their lesser dependence on control for successful efficiency outcomes. In aggregate, the results indicate that essentially all building types can be made to perform at 3.5 stars or above, and that in most cases 4 stars is feasible without changing HVAC system type or reducing PCA grade. This is important as it illustrates the strong potential for retrofit upgrades in the building stock rather than knock-down and rebuild.
Figure 1: NABERS Energy rating for different PCA property quality grades. 5
NABERS Energy Rating
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0
NABERS Energy Rating
5.5 5
PCA Grade
4.5 4 3.5
Figure 2.3 Impact of age on building performance. 2.5 2 1.5 1 0.5 0
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Figure 3. Impact of air-conditioning system type on performance. NABERS Energy Rating
5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0
System Type
5.2.
Finding 2: Air side economy cycles (free cooling) work.
The results clearly indicate that economy cycles produce an improvement in building performance. Statistically, the difference in means was 0.57 stars and the statistical confidence was approximately 98%, as illustrated in Figure 4. Of course, this finding has to be qualified to some extent – the sample was biased to temperate climates, and so the results do not indicate that buildings in tropical areas should install economy cycles. However, the use of economy cycles in temperate climates is strongly supported. Figure 4: Impact of economy cycle on performance 5
NABERS Energy Rating
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0
Economy Cycle
5.3.
Finding 3: Buildings perform better when managers undertake regular incremental upgrades and focus on eliminating older and unserviceable technologies. 5
5
4.5
4.5
NABERS Energy Rating
NABERS Energy Rating
There was strong support in the data for the proposition that sites that had conducted minor works in the past 5 years performed better on average than those that had not. For NABERS Energy, the effect was 0.6 stars at 97.7% confidence, while for NABERS Water the effect was 0.51 stars at 95.8% confidence. 4
3.5
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Figure 5. Impact of investing in low cost capital measures on performance 1.5
1
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0
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Yes
Low-cost Capital Measures - Energy Efficiency
No
Yes
Low-cost Capital Measures - Water Efficiency
Interestingly, sites that had reported major upgrades did not show a significant performance benefit when compared to those without major upgrades. This may be because such sites were coming from a very low performance base, or it may be that major upgrades genuinely don’t work. Anecdotal evidence would suggest that both of these factors may be true to some extent. It is recommended that this be a specific topic of further research, and will be targeted in stage 2 of the Low Energy High Rise project.
Figure 6. Impact of building technology on performance. Note in this context that a score of 1 represents modern good practice and as a result lower scores represent varying levels of poor practice.
The concept of focusing on elimination of older technologies arises from the aggregation of a number of questions relating to building technology, including glazing, cooling technology, air-conditioning type, air conditioning zoning and reheat, lamp technology and the control technology. A low score on this scale might typically reflect high solar exposure, poor cooling technology, badly zoned airconditioning, older lamp technologies and the presence of pneumatic controls, while a good score represents a highly shaded façade, modern cooling technology, good practice air-conditioned design, modern lamps and a digital control system. As such, it can be seen that the aggregate is not so much a measure of good technology as a measure of the degree to which the building fails to meet good practice. The result therefore indicates that a building with good basic infrastructure has a better chance of achieving a higher performance than a building that has significant impediments in design or equipment. The elimination of such heritage technology of course is often able to be conducted on an incremental basis, supporting the first half of the finding. 5.4.
Finding 4. Building that perform better measure and report NABERS performance to tenants and the wider public;
The interpretation of the statistical results for this finding required some care as there is a strong risk of reverse causality, i.e. buildings report because they perform well, rather than the other way around. To avoid this problem, the focus of analysis was placed on reporting to tenants separately from reporting to the public, as the former was considered to be less likely to be biased.
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Figure 7. Impact of reporting to tenants on NABERS Rating. The relationship shows a magnitude of 0.55 stars with a statistical significance of 95.7%.
The data in Figure 7 were built from the combination of answers on whether the site held regular meetings with tenants and whether they reported energy efficiency perofmance. As such it is indicative of a level of positive engagement with tenants being correlated with improved efficiency. For reference, the apparent impact of public reporting of energy and water ratings was approximately 0.5 stars at a confidence level of 96-98%. 5.5.
Finding 5. Buildings that perform better provide operators and maintenance staff/contractors with reason to care about the performance of the building
This finding is based on three separate statistical results, illustrated in Figure 8 and Figure 9. The first, and possibly most controversial, is that buildings that are managed by staff significantly outperform buildings managed by contractors. The second finding was that staff maintained buildings performed better than contractor maintained buildings, which showed a remarkably large impact of 0.86 stars at 97.6% significance. Finally there was a further result that the provision of incentives for efficiency to the maintenance contractors correlates with better performance. It is noted in this context that all respondents with such incentives actually applied penalties for non-performance rather than incentives for good performance.
5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0
NABERS Energy Rating
NABERS Energy Rating
Figure 8. Impact of whether the building manager is an employee or a contractor of the building owner.
Staff
Both
Contractor
Building Manager's Position
5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0
Contractor Employee Are you an employee of the building owner or a contractor?
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Figure 9. Impact of efficiency-related incentives for the maintenance team on NABERS performance 5
NABERS Energy Rating
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 No
Yes
Maintenance Team Incentivisation
While it is tempting to take a simplistic interpretation of these results and argue aggressively for insourcing of operation and maintenance, the depth of the sample and results are probably insufficient to draw such a strong conclusion. As a result, a less aggressive interpretation is preferable. In this case, it is clear throughout the results that better results accrue when the operators and maintenance workers have a reason to care about performance, be it because it affects them directly as staff of the owner or because there are penalties or incentives applied in relation to efficiency. 5.6.
Finding 6. Buildings that perform better have strong management leadership with regards to efficiency, share common objectives and agendas for efficiency throughout the management chain and retain efficiency savings in budgets
There were several results supporting this finding, specifically: • Sites reporting that the main driver for energy or water efficiency came from within the ownership group had better performance on average by 1.29 stars (same for both energy and water) at a confidence level of 99.2% (Figure 10). • Sites where multiple layers of management reported that they felt they had the ability to control energy efficiency had better performance on average by 0.88 stars at a confidence level of 99.3% (Figure 11). • There was a weak but significant correlation between the number of years that savings were retained in budget and the NABERS performance (Figure 12).
5
5
4.5
4.5
4
NABERS Water Rating
NABERS Energy Rating
Figure 10. Impact on performance of having owner group driving efficiency
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Owner Driven Energy Efficiency
No
Yes
Owner Driven Water Efficiency
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Figure 11. Impact on performance of having multiple managers with control over efficiency 6
NABERS Energy Rating
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Figure 12. Impact on performance of retaining efficiency savings for reinvestment
NABERS Energy Rating
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Years savings are retained for reinvestment for?
These factors together, point strongly towards a basic conclusion that organisations that decide to do something about energy efficiency do genuinely go on to achieve efficiency improvements. 5.7.
Finding 7. Buildings perform better when the staff are given training in energy efficiency and are not overly conservative with respect to efficiency technologies
Again, this finding was supported by multiple results: • Sites that reported that they had a training program for energy efficiency demonstrated a rating 0.51 stars higher than those that did not, at a confidence level of 98.3% (Figure 13). • Sites where the building managers reported that they had a higher level of skill in energy efficiency achieved better rating. This was the only result where skills appeared to translate to an impact on performance – notably formal qualifications did not appear to cause any impact on building performance. This probably reflects the lack of direct relevance in available formal qualifications (Figure 14). • Sites where the building manager indicated a conservative attitude (assessed as those who only considered investments in proven technology) showed a generally poorer performance. Interestingly, the strongest impact was that conservatism about water efficiency technologies had a 0.51 Star impact at 96.7% confidence on the energy rating (and a similar impact on the water rating); the impact of conservatism regarding energy efficiency technologies only achieved 81% significance and as a result was not counted. It is suspected that in this context water efficiency
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can act as a flag for more general conservatism, owing to the more recent appearance of water efficiency as an issue within office buildings in Australia (Figure 15). Figure 13. Impact of efficiency training programs on performance 5
NABERS Energy Rating
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 No
Ye s
Training Program - Energy Efficiency
Figure 14. Impact of the self-perceived energy efficiency skills of the manager on NABERS performance. 6
NABERS Energy Rating
5
4
3
2
1
0
-1 0
1
2
3
4
Manager's Perceived Skills Score
Figure 15. Impact of only investing in proven efficiency measures (yes indicates more conservatism
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NABERS Energy Rating
5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 No
Yes
Only Invest in Proven Measures 6.
Energy and Water
A strong feature of the data was the level of cross-correlation between actions in energy and actions in water with both the NABERS Energy and NABERS Water ratings. This implies that there is a strong relationship between those sites that successfully implement energy efficiency and those that successfully implement water efficiency. This is further supported by the strong similarities found between the significant findings for management and energy efficiency and those for management and water efficiency. This suggests that once the correct management structures are in place for one, the other follows.
7.
Conclusions
As part of the Low Energy High Rise project, a large scale survey and statistical analysis was undertaken to determine what technological and management factors appear to differentiate buildings with higher levels of energy and water efficiency from the balance of the market. A number of key factors showed statistical significance, including some technology factors, factors relating to the management structures and the presence of training and higher skill levels in building management staff. Impacts for each of these major areas range typically from 0.5-1.5 stars NABERS Energy Base Building. Although the high level of cross correlation between results means that it is not possible to treat these results additively, it is clear from the data that an improvement of 1-1.5 stars should be readily achievable through addressing the major findings of the report. This translates into a 30% improvement in sector performance which in turn translates in to a 1.2% reduction in Australia’s national greenhouse emissions. The scale of this impact is remarkable on two counts: • Compared to other countries, office buildings make up a relatively small proportion of Australia’s greenhouse emissions. • The findings relate to management and low-end technical measures rather than major capital upgrades. Furthermore, a higher total impact would appear possible on global greenhouse emissions, given that the findings would appear to be at least partly applicable to other parts of the commercial buildings sector, such as hotels and retail.
References [1]
http://www.nabers.com.au
[2]
Commonwealth of Australia, Green Lease Schedule Available http://www.environment.gov.au/sustainability/government/eego/publications/
online
at
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[3]
NSW Department of Environment, Climate Change and Water, 2009 NABERS annual report, Sydney, 2009
[4]
Commonwealth of Australia Building Energy Efficiency Disclosure Bill 2010, Canberra, 2010. Available online at http://parlinfo.aph.gov.au/parlInfo/download/legislation/bills/r4324_first/toc_pdf/10071b01.pdf;file Type%3Dapplication/pdf
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Bringing all parties to the table: overcoming barriers to energy efficiency in the world’s most famous building Paul Rode (Director, Business Development), Kelly Smith (Sustainability Programs Manager) Johnson Controls
Abstract Since its construction as the world’s tallest building in 1931, the Empire State Building in New York City has been an icon of modern culture. In 2009, a collaboration of five organizations announced a program to make the building a living demonstration in energy efficiency and sustainability. The Empire State Building case study demonstrates how multiple parties can work together to overcome common barriers to energy efficiency. While the performance contracting model has been successfully used for decades to implement efficiency retrofits in the public sector, office buildings have not traditionally benefitted from whole building retrofits due to misalignment of incentives between tenants and owners, the relatively long payback periods, and the complexity of existing mortgages and ownership structures. This building’s historic status presented additional challenges. The innovative approach used in the Empire State Building can serve as a model for deep retrofit projects in large multi-tenant office buildings, both new and historic, throughout the world. Using an iterative design process, the team narrowed down more than sixty potential energy efficiency ideas using whole building simulation to evaluate the interactive impact of packages of measures to arrive at the optimal balance of financial and environmental return on investment. The resulting project consists of a bundle of eight project components, ranging from the installation of digital building controls to refurbished, high-efficiency windows to an energy management system and demand-controlled ventilation for tenants. By including both building systems and tenant behaviours, this project cost-effectively reaches deeper levels of energy savings than typical retrofit projects. The approach is expected to result in 38% energy savings with a 3.1 year payback on incremental cost. This energy savings translates to 105,000 tons of avoided greenhouse gas emissions over a 15 year period.
Introduction The Empire State Building in New York City was the tallest building in the world from its construction in 1931 until 1979. A popular landmark and tourist destination and frequently depicted in film, photography and other art, it has become a symbol of the modern era, a cultural icon representing the engineering achievements of the twentieth century. The building itself stands 443 meters tall and serves over 260,000 square meters (2.8 million square feet) of rentable space spanning 102 floors [1]. The majority of the building is tenant-occupied office space, though the building also hosts retail and broadcasting activities. The building is managed by its owner, Empire State Building Company. In April 2009, a consortium of organizations announced a comprehensive project to increase the energy efficiency of the Empire State Building. The project team consists of leaders in various aspects of energy efficiency and commercial real estate: • • • • •
Johnson Controls – Energy services company Rock Mountain Institute – Energy efficiency expert Jones Lang LaSalle – Program manager Clinton Climate Initiative – Catalyst for climate change action Empire State Building Company – Property owner
When the implementation is complete, the Empire State Building will use 38% less energy, resulting in an annual savings of $4.4M and a reduction of 105,000 tonnes CO2 over the next fifteen years. These
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improvements will place the Empire State Building in the top 10% of U.S. commercial office buildings in terms of energy efficiency. While the project included rigorous engineering and technical analysis to create a plan for achieving these savings, none of the project measures alone represents a demonstration of novel technology. Rather, the innovation behind the project is the manner in which a group of diverse stakeholders was able to effectively collaborate to create an integrated solution that meets all the project objectives. This process allowed the team to overcome traditional barriers to energy efficiency and makes up the principal lessons learned through this experience.
Barriers to energy efficiency Many studies have explored the market barriers to the widespread adoption of energy efficiency. The central question behind all of this research is the “efficiency gap” first introduced in 1996 by researchers at Lawrence Berkeley National Laboratory [2]. This gap is defined as a difference between the energy efficiency decisions that should be made by rational individuals and those that actually are made. Typical studies quantifying the potential impact of energy efficiency identify numerous opportunities for implementing energy efficient equipment and building construction practices, estimating the savings potential for cost-effective projects to significantly offset the rising demand for energy in most parts of the world. Recent assessments of energy efficiency potential estimate the cost-effective potential savings in 2020 at 13% in the U.S. [3] and 15% in the EU [4], in comparison to “business-as-usual” projections. Significant research efforts have addressed the “efficiency gap” through the analysis of market barriers. These barriers can include structural, organizational, technical, informational, or other types of problems encountered when attempting to implement an energy efficiency project. Barriers have been analyzed by policy-makers, industry analysts and project implementers in an attempt to increase the market adoption and penetration of energy efficient practices, widely recognized as a low-cost and abundant resource for reducing societal greenhouse gas emissions. However, despite this large body of work, there are very few examples in the global discussion of successfully overcoming these barriers. This paper presents a specific instance of a project team that was able to address and overcome several common barriers to energy efficiency. Built in 1931, the Empire State Building is representative of the majority of office space in developed countries. Its aging infrastructure included pneumatic controls, a range of legacy mechanical systems and inefficient building shell. As a privately owned and operated commercial rental property, the building has been managed to meet tenant needs while minimizing cost. This objective has become more difficult in New York, where rising energy costs have presented an increasing challenge to an already competitive real estate market. An increasing global awareness of the climate change problem has further intensified the requirements on the building’s management, leading to Empire State Building involvement with local and state initiatives, including the PlaNYC effort to reduce the city carbon footprint by 30% between 2005 and 2030 [5]. A recent study by McKinsey defines a set of barriers that limit the implementation of energy efficiency projects in existing commercial buildings [6]. Each of these barriers is addressed and successfully overcome as part of the Empire State Building retrofit project plan. The barriers are explained here in the context of the project. The following section describes the approaches used to overcome these barriers. Lack of awareness or information Like many commercial properties, the Empire State Building is served by a highly complex array of mechanical systems. While some components have been designed to operate in an integrated fashion, others are completely independent. Adding complexity is the fact that equipment was added as needed over time, leading to today’s mix of various legacy systems with differing degrees of functionality. Coupled with variations in building load due to occupancy patterns and weather, the challenge of providing comfort to the building’s 900 tenants requires the full attention of a large staff of facility engineers and technicians.
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In the case of the Empire State Building, there is significant technical expertise in house about how to increase energy efficiency. In that sense, the barrier of lack of awareness and information does not apply. However, because of the complexity of the system, the present staff is strained to maintain operation. This effort to fulfill the building’s primary mission (i.e. provide comfort for tenants) prevents resources from being used to identify and pursue improvements in the building’s energy efficiency, even though that is an important goal of management. For this reason, a building like the Empire State Building is likely to be constrained by lack of awareness and information – not relating to technical expertise, but rather to a consistently applied approach to greater efficiency that is integrated with dayto-day operations. To overcome this barrier requires an internal “champion” that places high priority on the pursuit of energy efficiency opportunities. Because this individual has limited resources due to other duties, it is often necessary to introduce an outside party that can work with the champion to implement energy efficiency projects. This approach can lead to more comprehensive or “deeper” efficiency improvements and overcomes the barrier of limited awareness or information that is focused on the opportunities. Capital constraints Another barrier to energy efficiency in existing commercial buildings is availability of capital. Because of its aging infrastructure and operation in a competitive real estate market, the Empire State Building management must be extremely careful about allocation of capital among competing needs. This strain is aggravated by the impact of high and rising energy costs in New York City. Elevated hurdle rate Commercial buildings differ from those of government or non-profit organizations in that they are responsible for creating profit for stakeholders and therefore held to specific financial standards. This difference is illustrated in metrics like return on investment, which is typically required to be much higher in a commercial retrofit project than in a comparable project at a government or institutional site. Another metric commonly utilized in assessing energy efficiency projects is the simple payback period, defined as the initial cost of the project divided by the expected energy cost savings per year. A recent survey of decision-makers in commercial real estate positions found that the average payback period required for energy efficiency projects is 3.5 years [7]. This business requirement strictly limits the scope of potential retrofits and other projects by eliminating measures that provide savings over long periods of time. In many cases, payback requirements limit the bundle of energyconserving measures enough to make the entire project unattractive for a third party provider such as an energy services company. Both the limited scope and the prevented projects are means by which the elevated hurdle rate barrier is a significant hindrance to energy efficiency efforts in existing commercial buildings like the Empire State Building. Agency issues Another perennial problem faced by energy efficiency activities in commercial real estate is misalignment of incentives between those responsible for making decisions and facilitating projects and those who benefit from the projects. This barrier is often referred to as the “split-incentive problem” or “landlord-tenant” agency issues. As an example of this barrier, the Empire State Building ownership is responsible for maintaining structural elements and mechanical systems for the entire building as well as conditioning of common spaces. In addition, building ownership pays the utility bill for energy consumption in equipment such as lighting, office equipment, and terminal HVAC equipment such as fans. To account for this cost, present-day leases often include a standardized “adder” for energy. Because this fee is assigned based on the size of the tenant space and perhaps key factors related to energy use (e.g. high-load equipment), the tenants have minimal incentive to align their behaviours to reduce energy consumption. Under this arrangement, an upgrade to the building windows would be paid for entirely by the ownership, with the benefits split between the owner and tenants. This split weakens the economics for the project from the owner’s perspective. A second example is occupancy sensors for controlling lighting systems. Because the full benefits of this measure would go to the tenants, the building owner
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has no incentive to install the sensors. However, the tenants are also unlikely to implement a project like this because the remaining duration of their lease is less than the expected duration of the savings. A potential remedy to this barrier is the notion of building owners “passing through” the costs of efficiency upgrades in the form of rent premiums. Recent research has begun to quantify this effect empirically using commercial real estate data [8]. While there has been increasing discussion in the real estate community about “green leases” and other forms of implementing this concept, passing the costs of efficiency upgrades to tenants is in the early stages of market penetration.
Overcoming barriers to obtain results The Empire State Building retrofit represents a success story in aligning stakeholders to overcome barriers. The end result is a detailed retrofit plan, under implementation this year, which will achieve significant savings in energy, cost and carbon, and meet the goals of the building ownership, stakeholders involved, and city and state initiatives. When the project is completed, the Empire State Building will use 38% less energy and save $4.4 Million per year on energy costs. Over the next fifteen years, the project will avoid 105,000 tonnes of carbon dioxide emissions. While some of the key factors behind this project’s success are specific to the Empire State Building, others are general lessons that can be applied in similar projects to meet the dual objectives of reducing greenhouse gas emissions and improving the financial bottom line.
Lack of awareness or information The Empire State Building project involved a diverse team, with each party bringing a specific set of skills and experience to the table. One key to the success of this project was integration between these organizations. The project team overcame the lack of awareness barrier in two ways. First, the team brought with them a body of knowledge and experience about not only the technical underpinnings of the project, but also the organizational and work-flow aspects as well. Working closely with the Empire State Building ownership, this team was able to infuse significant information into the project. Second, the project team represented a focus on the goal of increasing energy efficiency that was greater in both level of concentration and duration than would have been possible if the building ownership had acted alone. The careful planning built into the project schedule optimized the team’s influence; analysis and planning for the project were performed through an iterative process that lasted eight months. Another method of overcoming this barrier is to simplify the project. This was accomplished in two steps for the Empire State Building. First, a detailed screening of energy efficiency measures revealed which were the most applicable and appropriate for the building. This screening was based on a thorough preliminary assessment of the building. Seventeen measures were identified as applicable for the project. The next step included additional analysis of the possible permutations of measures. Each “bundle” was assessed from a technical perspective through energy modeling and incorporated financial analysis as well. The team’s final recommendation included eight distinct measures, which together lead to the significant energy and carbon savings attained. Figure 1 illustrated the savings associated with the eight measures included in the final project recommendation.
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Figure 1: Annual Energy Savings by Measure
Annual Energy Use (tonnes of oil equivalent)
6,000 5,000 4,000
5,492
9% 6%
5%
5%
5%
3%
3%
2%
3,392
3,000 2,000 1,000 0
In addition, the timing and location of the project provided an additional support toward overcoming this barrier. As mentioned above, local, regional, and world trends toward sustainable buildings are an important factor in New York. Specifically, city legislation has been proposed that would make retrofits of existing buildings mandatory. These macroscopic trends certainly contributed to a heightened level of awareness and availability of information at all stages of the project. Capital constraints The Empire State Building began this project in a unique situation with respect to the capital constraint barrier. Because of the timing of the project within the capital planning cycle of the building, the energy efficiency investments were able to be incorporated as a small part of a large scale renovation project. While most comparable office buildings do not have the option of scheduling efficiency retrofits that align with renovations, there are several generalized lessons that can be drawn from the manner in which the Empire State Building project was able to overcome this barrier. First, the project planning process included an optimized hierarchy of efficiency measures. This approach has been referred to as “doing the right things in the right order.” For example, the renovation plans had included the expansion of the building’s central chiller plant to meet increasing demands for cooling. However, improvements in the building shell analyzed during the planning process found that this increase in cooling demand could be alleviated by reducing waste energy, thus eliminating the need for an expensive increase to the chiller plant. Instead, the existing chillers will be retrofit for optimal efficiency. The workflow for this strategy is depicted in Figure 2, which shows that building loads are reduced first, followed by the installation of high efficiency equipment and then control capability.
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Figure 2: Sequence for evaluating and implementing energy efficiency measures
Reduce Loads
Use Efficient Technology
Provide Controls A second approach to overcoming the capital constraint barrier is integrated scheduling. For some of the measures considered for the Empire State Building, renovation plans for the next several years could potentially conflict with the retrofit project. Instead of working independently, this project was designed to incorporate with capital planning. For example, planned replacements of equipment such as air handlers serve as an opportunity for more efficient, variable air volume units to be installed for minimal incremental cost. As a result of this integration, the Empire State Building receives over $100 million of energy efficiency investment while only paying $13 million of incremental cost. Table 1 breaks down this effect for each of the eight measures recommended. Table 1: Integration of measure costs with capital planning process Project Description
Projected Capital Cost
2008 Capital Budget
Incremental Cost
EstimatedAnnual Energy Savings*
Windows
$4.5m
$455k
$4m
$410k
Radiative Barrier
$2.7m
$0
$2.7m
$190k
DDC Controls
$7.6m
$2m
$5.6m
$741k
Inc. above
$0
Inc. above
$117k
Chiller Plant Retrofit
$5.1m
$22.4m
-$17.3m
$675k
VAV AHUs
$47.2m
$44.8m
$2.4m
$702k
Tenant Day/Lighting/Plugs
$24.5m
$16.1m
$8.4m
$941k
Tenant Energy Mgmt.
$365k
$0
$365k
$396k
Power Generation (optional)
$15m
$7.8m
$7m
$320k
$106.9m
$93.7m
$13.2m
$4.4m
Demand Control Vent
TOTAL (ex. Power Gen)
A third method of overcoming the capital constraint barrier utilized in this project is to incorporate third party financing through a performance contracting vehicle. This approach, commonly employed by energy services companies in the public and institutional sectors, is an effective means of leveraging investments in energy efficiency by lending against the expected savings of the investment. These contractual arrangements are enabled by a performance guarantee offered by the implementer to reduce the financial risk on both the financier and the building owner. A key piece of the energy performance contract is a clear plan for measurement and verification of the savings over time, including mutual agreement about changes in building use and other factors that necessitate reevaluation.
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Elevated hurdle rate After reducing the capital required for the energy efficiency retrofit project in the Empire State Building, the bundle of measures selected for final implementation entail a simple payback of three years ($13.2M initial investment, $4.4M annual savings). This project falls into the range of acceptable hurdle rates for projects in existing commercial buildings. From the group of seventeen energy efficiency measures resulting from the preliminary screening, thousands of permutations were possible for implementation. Choosing the bundle that met the Empire State Building objectives required a deliberate analysis of the tradeoff between financial return and comprehensiveness of the savings. This tradeoff was apparent in the analysis of each potential bundle of measures along two key axes: net present value of the investment and greenhouse gas reduction over the project horizon. Figure 3 illustrates the relationship between these two quantities by plotting four bundles that were considered. As the figure shows, maximizing financial return leaves behind significant opportunities for cost-effective savings. Further, selecting a bundle that would provide the greatest reduction in greenhouse gas emissions would entail unattractive financial returns, even crossing into a net loss. Performing this analysis was a key mechanism that allowed the building ownership to match a solution to their goals and priorities. The approach selected for the Empire State Building is labeled “NPV Mid” in the chart below. Figure 3: Financial return and greenhouse gas savings for bundles of measures
Thousands
Net Present Value of Package of Measures
15-Year NPV of Package versus Cumulative CO2 Savings $35,000
NPV “Max” NPV “Mid” $15,000
NPV “Neutral”
($5,000) 0
40,000
80,000
120,000
160,000
Cumulative metric tons of CO2 saved over 15 years “Max CO2” Reduction
($25,000)
The same concept can also be seen at the individual measure level. The cost of each avoided ton of carbon dioxide is plotted for each of the initial seventeen measures in Figure 4. Note that some of the measures have negative cost of carbon, implying that the financial payback from energy savings more than compensates for the initial measure cost. Other measures reduce carbon at higher cost. The first 90% of the savings from these measures has an average carbon cost of negative $200 (-$200) per tonne. In contrast, the remaining ten percent of the savings costs upwards of $300 per tonne. By adopting the set of measures that optimized the tradeoff between savings and return, the project team was able to overcome the barrier of elevated hurdle rate.
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Figure 4: Cost of greenhouse gas reductions for initially screened measures
Cost per Metric Ton of CO2 by Individual Measure Cost per Metric Ton of CO2
$4,000
$2,000
$0
($2,000)
Agency issues The split incentive problem was also addressed as part of the Empire State Building project. As mentioned above, the building is occupied by tenants under various leasing arrangements. In a significant portion of the building, tenants have traditionally paid for energy as a standardized “adder” on top of their rent. Because these tenant spaces were not individually metered, it was impossible to charge them individually for the electricity they consume. This structure, common in many commercial real estate markets, inherently lacks the incentive system for tenants to change their behaviour and optimize energy use. A first step, then, toward overcoming the agency issue and effect a change in tenant behaviour is to provide the necessary information. This is being accomplished in the Empire State Building by adding tenant-level sub-meters where they do not already exist. As tenants turn over and new leases are signed, energy consumption will be treated as a pass-through from the building ownership’s standpoint, and the full impetus to implement behavioural changes will fall on the tenants, who will then be in a position to reap the rewards in the form of lower energy bills. In addition to the metering and the leasing arrangement, access to information has been shown to be a major factor in altering energy usage patterns. As an example, recent work in the residential sector estimates that providing electric customers with information leads to an average reduction in usage of seven percent [9]. With a more concentrated focus on managing cost, business customers could be even more responsive to energy information. This hypothesis is one reason that tenant energy management systems are being provided as part of the Empire State Building project. These systems will provide tenants access to their energy consumption data through a configurable and intuitive web interface. It is expected to account for roughly eight percent of the overall savings achieved through the project. Finally, the project was able to overcome the agency issues barrier by modifying the leasing structure in the building to better match the investments in energy efficiency with beneficiary. For measures such as windows, radiant barrier, and digital controls, the benefits will be split between tenants and the building ownership. Others, such as a chiller retrofit, will reduce the energy bills of the building ownership and have no direct impact on the tenants. Yet another set of measures, such as tenant daylighting, plug load occupancy sensors, and a tenant energy management system, will benefit the tenants exclusively. As the project proprietor and building owner, Empire State Building Company is assuming all of the upfront costs associated with the project. To adjust for these split incentives, the
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project assumes a “green premium” for future leases that will allow the ownership to recover the cost of these investments over the years to come.
Conclusions The Empire State Building retrofit project announced in 2009 provides an example of a project team overcoming traditional barriers to energy efficiency. As a result, the project will accomplish the two principal objectives of a significant reduction in greenhouse gas emissions (38% energy savings, 105,000 tonnes CO2 over 15 years) and healthy financial returns ($4.4M per year in energy savings and 3 year simple payback). The project involved technical and engineering innovation. More significantly, however, was the innovative approach to planning and design which allowed the building ownership to meet its objectives. Part of this process was overcoming the traditional barriers to energy efficiency investments in the existing commercial market: • Lack of awareness or information • Capital constraints • Elevated hurdle rate • Agency issues For each of these barriers, the project team adopted innovative strategies that can be extended and applied to similar projects in other existing buildings. By addressing and overcoming barriers in this manner, many more buildings will be able to execute energy efficiency retrofit projects and significantly reduce energy costs and greenhouse gas emissions around the world.
References [1]
http://www.esbnyc.com/tourism/tourism_facts.cfm?CFID=35660041&CFTOKEN=39762699
[2]
Golove W. and Eto J. Market Barriers to Energy Efficiency: A Critical Reappraisal of the Rationale for Public Policies to Promote Energy Efficiency. Energy and Environment Division, Lawrence Berkeley National Laboratory. March 1996.
[3]
Assessment of Achievable Potential from Energy Efficiency in the U.S. (2010-2030). EPRI, Palo Alto, CA: 2009. 1016987.
[4]
Study on the Energy Savings Potentials in EU Member States, Candidate Countries and EEA Countries. Fraunhofer ISI: March 2009.
[5]
http://www.nyc.gov/html/planyc2030/html/emissions/emissions.shtml
[6]
Unlocking Energy Efficiency in the U.S. Economy. McKinsey Global Energy and Materials: July 2009.
[7]
Johnson Controls and International Facility Management Association, Energy Efficiency Indicator. Available at http://johnsoncontrols.mediaroom.com/index.php?s=112&cat=94 May 2009
[8]
Eichholtz, P., Kok, N. and Quigley, J. Doing well by doing good? Green office buildings. UC Berkeley Fisher Center Program on Housing and Urban Policy: August 2009.
[9]
Faruqui,A., et. al. The impact of informational feedback on energy consumption – a survey of experimental evidence. Energy (2009). Doi;10.1016/j.energy, Elsevier: July 2009.
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Reducing Energy Consumption and Peak Demand in Commercial Buildings Iris Sulyma and Ken Tiedemann BC Hydro, Vancouver, Canada
Abstract BC Hydro’s Power Smart Product Incentive Program (PIP) offers financial incentives to encourage business and institutional customers to install a wide variety of simple retrofit installations and save energy. The purpose of this paper is to provide a market and impact evaluation of the Product Incentive Program. The market evaluation examines end use electricity consumption by building type and the nature of program participation by building segment. The impact evaluation examines the program’s energy impacts, peak impacts and cost effectiveness.
Introduction BC Hydro’s Power Smart Product Incentive Program (PIP) began in November 2003. PIP offers financial incentives to encourage business and institutional customers to install a wide variety of simple retrofit installations and save energy. A wide variety of products are eligible for PIP, although the bulk of savings to date have come from energy efficient lighting products. The program is administered primarily through an online application site over the Internet, which simplifies application procedures and keeps program administrative costs low. The goals of PIP include the following. (1) Generate energy savings for BC Hydro by replacing inefficient technologies with more efficient technologies. (2) Increase energy efficiency awareness by actively communicating energy efficient product options. (3) Educate customers on the benefits of energy efficient products. (4) Contribute to market transformation for specific technologies. (5) Better meet the needs of underserved small and medium business customers. (6) Increase business customer satisfaction. This purpose of this paper is to provide a market and impact evaluation of the Product Incentive Program. The market evaluation examines end use electricity consumption by building type and the nature of program participation by building segment. The impact evaluation examines the program’s energy impacts, peak impacts and cost effectiveness.
Data and Method Data extracts containing information on all the PIP projects completed in fiscal year F2008 (April 1, 2007 through March 31, 2008) were obtained in February 2009. The extract contained a variety of information on existing PIP projects including program dates, application status, types and quantities of products installed, estimated energy savings, and incentives awarded. This database was analyzed to provide an overview of PIP program activity. Customer awareness, satisfaction, program experiences, and respondent free rider and spillover questions were summarized from a telephone survey of 150 program participants conducted in the spring of 2008. Participant respondents were recruited from a list of PIP applications for the relevant period. Gross and net energy savings were estimated for program activity completed in the period April 1, 2007 through March 31, 2008. Gross savings are the basic estimate of program savings and are usually based on an engineering study and/or technical calculations. Gross savings generally do not account for factors external to the program that could impact energy savings and may therefore include energy savings that are not attributable to the program. In contrast, net savings are estimated by adjusting the initial gross savings estimates by the expected influences of non-Program related factors including free-ridership, spillover, and naturally occurring conservation.
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Gross savings estimates for PIP are calculated automatically when the customer enters the project information into the online application form, with these estimates relying on deemed savings algorithms for each technology type. Gross evaluated electricity savings were estimated using the following algorithm, where W pre and W post are the wattages of the original and replacement products, hours refers to hour of use for the relevant space type, area refers to the area of the relevant space type and the summation is over areas: (1)
Gross kWhsavings = Sum (W pre – W post) * hours of usearea /1000.
Since the program applications provided these calculations with assumed hours of use, the major calculation here was to correct the assumed hours of use by space-weighted actual hours of use based on metering data. Gross peak demand was estimated by using the ratio of average kWh to peak kWh from engineering analysis. Net electricity savings were estimated using the following algorithm, W pre and W post are the wattages of the original and replacement products, hours refers to hours of use for the relevant space type, area refers to the area of the relevant space type, and the summation is over areas: (2)
Net kWhsavings = Sum (W pre – W post) * hours of usearea /1000*(1 – free rider rate + spillover rate).
Net peak demand was estimated by using the ratio of average kWh to peak kWh from previous engineering studies. We compared the cost effectiveness of the main technologies installed under PIP using the cost of conserved energy, where the estimated installed cost for each technology came from data collected for the pre-program baseline. The cost of conserved energy is the ratio of the present value of the stream of costs to the present value of energy saved. If all costs occur at time zero, then the cost of conserved energy (CCE) can be written as follow where cost refers to the full installed cost of the product, gross kWh refers to savings for the technology, d is the discount rate of 0.06, and n is the useful life of the product, which we assume is ten years: (3)
CCE = (cost/KWhsaving)*(d/ (1 – (1 + d)-n).
End Use Consumption Table 1 summarizes end use electricity consumption for commercial and institutional buildings. This data is based on site visit data used to inform DOE 2.1 modeling of 316 commercial and institutional buildings. The information provided annual end-use consumption per square foot, based on normal weather and full occupancy for thirteen building segments (grocery, hotel/motel, health care, low rise office, high rise office, library, recreation centre, retail, restaurant, elementary school, secondary school, wholesale and miscellaneous) for ten end-uses (space cooling, space heating, interior lighting, equipment, HVAC auxiliaries, refrigeration, exterior lighting, elevators, domestic hot water and cooking). Three features of this data are worth noting. First, average total consumption per square foot per year varies substantially across building segments, from a low of 10.2 kWh per square foot per year for elementary schools to a high of 74.0 kWh per square foot per year for grocery stores. Second, for most building segments, interior lighting is the most important end use with refrigeration for grocery stores and recreation centres, domestic hot water for hotels/motels, and equipment for restaurants and miscellaneous establishments among the biggest end uses. Third, given the relative sizes of the various end use loads, the best opportunities for future energy savings include space cooling, space heating, interior lighting, equipment and HVAC auxiliaries such as fans and pumps.
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Table 1. End-use Electricity Consumption (kWh/ft2/year)
Facility type
Cool
Heat
Int light
Equip
HVAC aux
Refrig
Ext light
Elev
DHW
Cook
Total
Grocery
2.4
1.9
14.4
4.6
5.6
28.0
3.0
0.3
4.2
9.6
74.0
Hotel/motel
1.1
4.7
6.1
2.7
2.7
1.1
0.8
0.8
10.1
1.1
31.2
Health care
0.5
4.3
5.7
1.9
3.3
0.5
0.4
0.5
1.6
0.7
19.4
High rise off
2.9
3.3
8.0
2.8
4.4
0.1
0.7
0.6
0.8
0.3
23.9
Low rise off
1.9
2.7
7.1
2.5
3.5
0.5
0.8
0.8
0.4
0.4
20.6
Library
1.5
3.7
8.2
1.8
3.1
0.1
0.9
0.8
0.5
0.2
22.2
Rec centre
1.4
2.6
6.9
2.8
6.8
9.2
0.6
0.5
1.0
0.6
32.4
Retail
1.8
2.3
9.9
2.3
3.5
0.1
3.1
0.6
0.9
0.5
25.0
Restaurant
3.5
4.0
9.7
17.8
9.2
3.2
4.3
0.2
3.6
10.0
65.5
Elem school
0.2
2.8
3.5
0.5
1.8
0.1
0.3
0.2
0.2
0.6
10.2
Sec school
0.3
4.4
4.1
0.8
2.1
0.1
0.3
0.1
1.0
0.2
13.4
Wholesale
1.1
3.9
7.8
5.3
2.4
15.9
0.9
0.2
0.5
2.2
39.2
Miscellaneous
1.9
2.6
7.9
16.1
7.0
1.6
1.5
1.0
1.5
0.3
41.4
Customer Survey Customers were asked how they became aware of program awareness for PIP. The most important electrical distributor or contractor (37%), BC Representative (31%), BC Hydro website (19%) literature (14%).
PIP. Table 2 shows their main reported sources of sources of customer awareness of PIP were an Hydro Account Manager or Customer Care and BC Hydro bill inserts or other promotional
Table 2. Sources of Participant Awareness of PIP (%) Source
Share (%)
Electrical distributor or contractor
37
BC Hydro Account Manager or Customer Care Representative
31
BC Hydro website
19
BC Hydro bill inserts or other promotional literature
14
Consultants or other service firms
12
Colleagues
10
Trade publications
2
Don’t know/ refused
4
Customers were asked about the importance of various factors in their decision to participate in PIP. Table 3 provides participants’ responses to a series of questions on the importance of various factors on their decisions to participate in the Product Incentive Program. The response categories were as follows: (1) not at all important; (2) not very important; (3) neither important nor unimportant; (4) somewhat important; (5) very important; and (6) don’t know or not applicable. The most important
375
factors included reducing energy use to save money (top box score of 4 or 5 out of 5 of 89%) and reducing energy use to save the environment (top box score of 4 or 5 out of 5 of 89%). Table 3. Importance of Various Factors on PIP Participation Decision (%) 1
2
3
4
5
DK
Advice from a BC Hydro representative
10
8
17
26
29
9
Advice from contactor or distributor
5
9
18
127
37
5
Reducing energy use to save money
0
0
9
18
71
1
Expected incentive from the program
1
5
19
41
32
3
Reducing energy use to benefit environment
1
2
7
24
64
1
Customers were asked about their satisfaction with various components of PIP. Table 4 provides participants’ responses to a series of questions on their satisfaction with components of the Product Incentive Program. Once again, the response categories were as follows: (1) not at all satisfied; (2) not very satisfied; (3) neither satisfied nor dissatisfied; (4) somewhat satisfied; (5) very satisfied; and (6) don’t know or not applicable. Areas with high satisfaction levels included service provided by contractors, distributors and BC Hydro personnel. Areas with lower levels of satisfaction included direct mail information about PIP and the level of incentives offered. Table 4. Customer Satisfaction (%) 1
2
3
4
5
DK
Direct mail information about PIP
6
6
22
33
15
19
Information about PIP on website
1
2
13
41
31
13
Service provided by BC Hydro personnel
3
3
8
32
48
5
Service provided by your distributor
0
2
10
31
52
4
Service provided by your contractor
0
2
3
27
56
10
Level of incentives offered
3
5
23
40
28
1
Variety of products funded under the program
1
4
17
48
23
1
Usability of the online application
0
7
14
33
35
11
Application procedures to receive funding
1
5
16
35
40
3
Your overall experience with the program
1
2
10
42
45
0
Market Analysis The market analysis focused on two main considerations. First, what were the amounts and shares of the main products installed through PIP? Second, what were the main facility types and shares participating in PIP? Table 5 provides information on product installations and incentives paid by type of product. The total number of products installed under PIP for F2008 was 276,751. The product shares were: standard T8 lamps (5.1%); energy saving T8 lamps (60.0%); compact fluorescent lamps or CFL (17.2%); metal halide lamps (2.3%); halogen infrared lamps (0.9%); other lighting products (11.0%); and mechanical and other products (3.6%). It is worth noting that lighting products made up about 96% of all products installed under PIP while lighting products made up about 87% of incentives paid. Table 5. PIP Product Installations by Type, F2008
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Quantity
Incentives paid
Number
Share (%)
Dollars
Share (%)
Standard T8 inc ballasts
14,048
5.1
194,800
15.6
Energy saving T8 inc ballasts
165,979
60.0
533,018
42.7
CFL
47,675
17.2
135,136
10.8
Metal halide
6,263
2.3
81,728
6.5
Halogen infrared
2,393
0.9
2,471
0.2
Other lighting products
30,487
11.0
138,505
11.1
Mechanical and other
9,906
3.6
163,171
13.1
276,751
100.0
1,248,829
100.0
Total
Table 6 summarizes the distribution of PIP applications by facility type. The total number of applications under PIP for F2008 was 697. The applications shares were: large grocery (1.0%); hotel/motel (24.5%): health care (3.7%); office (20.5%); large retail (1.9%); restaurant (1.6%); elementary school (2.6%); secondary school (2.0%); wholesale/warehouses (1.0%); industrial (4.6%); miscellaneous (18.9%): and unknown (17.8%). It is worth noting that program activity is quite concentrated by building segment, as just two building segments (hotel/motel and offices) account for 45.0% of the applications.
Table 6. PIP Applications by Facility Type, F2008 Facility type
Number of applications
Share (%)
Large grocery
7
1.0
Hotel/motels
171
24.5
Health care
26
3.7
Office
143
20.5
Large retail
13
1.9
Restaurant
11
1.6
Elementary school
18
2.6
Secondary school
13
2.0
Wholesale/warehouses
7
1.0
Industrial
32
4.6
Miscellaneous
132
18.9
Unknown
124
17.8
Total
697
100.0
Energy and Peak Impacts Gross and net energy savings were estimated for program activity in the period April 1, 2007 through March 31, 2008, using the methods outlined above. The results are shown by technology group in Table 7, where FR stands for free rider rate and SO stands for spillover rate. Annualized net savings were as follows: standard T8 (2.0 GWh); energy saver T8 (5.3 GWh); CFL (11.2 GWh); metal halide (1.6 GWh); halogen infrared (0.3 GWh); other lighting (2.6 GWh); and mechanical and other (1.9GWh).
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Table 7. Estimated Energy Impacts Technology
Gross savings
1 – FR + SO
Net savings
Standard T8
1.786
1.033
1.972
Energy Saver T8
4.524
1.105
5.344
CFL
10.011
1.045
11.183
Metal halide
1.449
1.019
1.578
Halogen infrared
0.332
0.796
0.283
Other lighting
2.358
1.019
2.569
Mechanical and other
1.874
0.989
1.853
Total
22.334
24.782
Table 8 summarizes evaluated energy savings and peak savings for the Product Incentive Program for F2008. Evaluated energy savings were 24.8 GWh compared to program reported energy savings of 27.5 GWh. Evaluated peak savings were 3.4 MW compared to program estimated based peak savings of 3.8 MW. Evaluated savings are about 90% of reported savings for the period covered by this study. The difference between reported and evaluated energy savings is due to two factors. First, the evaluated weighted average hours of use based on end use metering is lower than the hours of use used in the program algorithms which were used to generate program savings estimates. Second, the evaluated net realization rate (that is, the quantity one minus the free rider rate plus the spillover rate) is higher than that used in the program algorithms. Note that these two effects are offsetting in the sense that the first factor reduces estimated savings while the second factor increases estimated savings. Table 8. Program Energy Savings and Peak Savings Program Product Incentive Program
Period F2008
Energy (GWh)
Peak (MW)
Reported
Evaluated
Reported
Evaluated
27.5
24.8
3.8
3.4
Cost Effectiveness Table 9 summarizes cost effectiveness for sixteen main technologies installed under PIP. The cost of conserved energy estimates vary quite widely across product categories. For lighting products, the cost of conserved energy varies from $0.016 per kWh for energy saver T8 fluorescent tubes to $0.048 per kWh for pulse start metal halide lamps and for photocell lighting controls. For mechanical products, the cost of conserved energy varies from $0.014 per kWh for synchronous belts to $0.060 per kWh for adjustable speed drives Table 9. Cost-effectiveness of Selected Technologies Technology
Installed cost ($/unit)
Savings (kWh/year)
CCE ($/kWh)
Pulse start metal halide
104.90
296
0.048
Halogen infrared
18.50
58
0.044
Occupancy sensor lighting
75.00
443
0.023
Photocells
60.20
173
0.048
378
Energy saver T8
3.00
25
0.016
Energy saver T8 and ballast
42.70
239
0.024
High bay fluorescent
170.00
523
0.044
High wattage CFL
9.50
202
0.047
Standard wattage CFL
2.75
104
0.027
5,000.00
42,300
0.016
ASDs (per horse power)
400.00
900
0.060
Synchronous belts
14.80
140
0.014
Transformers (per kVA)
27.30
70
0.053
50,000.00
135,000
0.050
HVAC occupancy sensor
239.40
1,080
0.030
Carbon dioxide sensor
747.70
2,970
0.034
Switch plate timer
61.50
288
0.029
Pony pump motors
Harmonizers
Summary of Findings Overview. PIP has been successful in building a high level of product awareness and purchase behaviour for energy efficient lighting products in the commercial sector and institutional sector. The program has been gaining momentum, with increased customer applications for efficient lighting products and, to a lesser extent, for mechanical products leading to increased annual savings. End Use Consumption. DOE 2.1 models based on detailed on-site audits were used to examine end use consumption by building type. The analysis found that: (1) total consumption per square foot varies substantially across building segments, from a low of 10.2 kWh per square foot per year for elementary schools to a high of 74.0 kWh per square foot per year for large grocery stores; and (2) for most building segments, interior lighting is the most important end use with refrigeration for large grocery stores and recreation centres, domestic hot water for hotels/motels, and equipment for restaurants and miscellaneous establishments among the biggest end uses. Customer Survey. A detailed survey was conducted with 150 program participants, covering a range of program aspects. Customers were asked how they became aware of PIP, and the most important sources of customer awareness of PIP were an electrical distributor or contractor (37%), the BC Hydro Account Manager or Customer Care Representative (31%), BC Hydro website (19%) and BC Hydro bill inserts or other promotional literature (14%). Customers were asked about the importance of various factors in their decision to participate in PIP: the most important factors included reducing energy use to save money (top box score of 4 or 5 out of 89%) and reducing energy use to save the environment (top box score of 4 or 5 of 89%). Customers were asked about their satisfaction with various components of PIP: higher satisfaction levels areas included service provided by contractors, distributors and BC Hydro personnel, while lower satisfaction levels included direct mail information about PIP and the level of incentives offered.
Market Analysis. To understand market impacts, we examined the distribution of applications by product type and by facility type. Total product installations under PIP for F2008 were 276,751. The product shares were: standard T8 (5.1%); energy savings T8 (60.0%); CFL (17.2%); metal halide (2.3%); halogen infrared (0.9%); other lighting products (11.0%); and mechanical and other products (3.6%). Program activity is quite concentrated as just two building segments (hotel/motel/start and offices) account for 45.0% of identified applications. Energy and Peak Impacts. Gross and net energy savings were estimated for program activity in the period April 1, 2007 through March 31, 2008, as shown in Table 3.11. This evaluation addressed gross program savings as follows: (1) the gross savings algorithms and parameter assumptions used
379
in the calculation of program deemed savings were reviewed and modified using BC Hydro light logger data provided by the Measurement and Verification department and reference data used by other similar incentive programs; (2) net savings were based on gross savings modified by survey based free rider and spill over rates. Evaluated energy savings are 24.7 GWh compared to program reported energy savings of 27.5 GWh. Evaluated peak savings are 3.4 MW compared to peak savings based on the program reported energy savings of 3.8 MW. Cost Effectiveness. The cost of conserved energy estimates vary quite widely across product categories. For lighting products, the cost of conserved energy varies from $0.016 per kWh for energy saver T8 fluorescent tubes to $0.048 per kWh for pulse start metal halide lamps and for photocell lighting controls. For mechanical products, the cost of conserved energy varies from $0.014 per kWh for synchronous belts to $0.060 per kWh for adjustable speed drives. Key Learnings There are four main sets of key learnings from this study. These four sets of key learnings cover the following areas: program organization and management; program planning; program delivery; and program monitoring, evaluation and reporting. Program Organization and Management. (1) Define clearly project management roles and responsibilities, so that customers and trade allies see a unified and seamless program process, and so they understand who they should turn to when there are problems or issues. (2) Adjust the program scope to reflect new opportunities and challenges in the market, while ensuring that revised program definition and strategies are clearly communicated to program staff and stakeholders. (3) Use trained and experienced engineering and technical staff. Since projects in large commercial buildings are often complex and unique to a specific site, trained and experienced staff are critical in ensuring that projects are well conceived and implemented. Program Planning. (1) Conduct adequate market research before program launch to understand market barriers and drivers, identify and build contacts with key market players, and align the goals and needs of market players and the program. (2) Develop a program plan with a clearly articulated program logic that clearly states the program objectives, operational outputs and resources required, so that stakeholders know what the program seeks to accomplish and why it has the stated objectives. (3) Ensure that program objectives are clear, well defined, measurable and achievable given available resources. Program Delivery. (1) Leverage scarce marketing dollars through partnerships and cooperation with other market players, and ensure that marketing communications are clear, simple and focused. (2) Understand product features, reliability, energy and demand savings, and product price before including the product in the program offer. (3) Ensure that incentives are an appropriate instrument in the context of the market being addressed, and that other instruments such as standards development, labeling or information are not more cost effective or appropriate given barriers to purchase for the product. Program Monitoring, Evaluation and Reporting. (1) Assess customer satisfaction through program evaluation surveys, and address both substantive material issues and problems and concerns which are identified through appropriate modifications to program design, program marketing or delivery. (2) Build systems to track sales levels and market shares, as well as their changes over time. (3) Develop appropriate algorithms to estimate energy savings and demand savings, and collect suitable data through surveys, site visits, shelf stock surveys and metering so that credible evaluation estimates can be made in a timely manner.
References [1]
Cavalli, J., M. Meyers, J. Flanager, M. Ruffo and C. Dickerson. How to Cost Effectively Serve Small Non-residential Hard to Reach Customers. Proceedings of the 2003 International Energy Program Evaluation Conference.
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Eto, J., S. Kito, L. Shown and R. Sonnenblick. Where Did the Money Go? The Cost and Performance of the Largest Commercial Sector DSM Programs. Berkeley, USA: Lawrence Berkeley National Laboratory, Report LBL-38201, 1995.
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Global Energy Partners. California Summary Study of 2001 Energy Efficiency Programs. Lafayette, USA: Global Energy Partners, LLC, 2003.
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Jones, A., S Feldman, P. Landry, M. Sedmak and M. Meyers. A Novel Method for Assessing Large Customer Wants and Needs. Proceedings of the 2001 International Energy Program Evaluation Conference, 2001.
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Kushler, M., E. Vine and D. York. Energy Efficiency and System Reliability: A Look at Reliability-Focused Energy Efficiency Programs Used to Help Address the Electricity Crisis of 2001. Washington, USA: ACEEE Report Number U021, 2002.
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Mapp, J., B. Smith and J. Reed. The Untapped Resource: CFLs in the Commercial Sector. Proceedings of the 2005 International Energy Program Evaluation Conference, 2005.
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Morgan, R. and T. Burnett. 2000. Large Commercial Customer Account Management Strategies. Proceedings from the 11th National Energy Services Conference, 2000.
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Patil, Y., S. Haselhorst, M. D’Antonio and G. Epstein. 2005. NSTAR Business Solutions Program Evaluation: Noteworthy Approaches and Findings from a C&I Retrofit Program Evaluation. Proceedings of the 2005 International Energy Program Evaluation Conference, 2005.
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Quantum Consulting. 2004. National Energy Efficiency Best Practices Study. Volume NR1 – Non-residential Lighting Best Practices Report. Berkeley, USA, 2004.
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York, D. and M. Kushler. 2003. America’s Best: Profiles of America’s Leading Energy Efficiency Programs, Report Number U032. Washington, USA: ACEEE, 2003.
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Façade Zone in relation to Energy, Indoor Environment and Cost in office buildings Maria Kikira a, Harry Bruhns b Architect, BSc, MSc, Department of Buildings, Division of Energy Efficiency, Centre for Renewable Energy Sources and Saving-C.R.E.S., and researcher, UCL Energy Institute, University College London, UK b Principal Research Fellow, UCL Energy Institute, University College London, UK a
Abstract The aim of this paper is to introduce façade energy, indoor environment and cost implications in office buildings with a LCC approach. The construction industry’s background has been changing and façade design is no longer determined solely by architectural concept or building image, but is also strongly related to energy and economic performance during all phases of construction process. Which are the characteristics of the façade that affect internal conditions, environmental, energy and cost performance? What need to be considered in the initial design concept by looking at a façade in the context of a buildings’ whole life performance? Post occupancy evaluation and detailed monitoring work is needed in order to understand the performance of façade inner perimeter zone. Empirical monitoring data from existing UK office buildings is under development in order to identify and justify parameters that affect the working and built environment (inner and outer) related to the building façade. Results obtained from the study will enrich the understanding of façade zone performance and bring under discussion a holistic approach in façade design considerations.
Introduction The envelope of the building is a predominant parameter that affects building’s energy performance and indoor environment, in parallel to internal gains, to mechanical systems network, to external conditions and climate. All parameters influence in a certain level and by case, however it is uncontested that a poor façade design greatly contributes to poor energy performance and indoor comfort. It is a rather complex, interesting and vital element to study in an integrated approach, from theories and physics to actual performance and operational monitoring. The façade, being the ‘clothing’ of a building, needs to satisfy various and often contradictory parameters which are prioritised differently by participating players in the building process, either in new buildings or those undergoing refurbishment. Such parameters are: architectural appearance, aesthetics and culture, energy and visual performance, environmental footprint, cost implications, envelope transparency, climate adaptation, structural and fire specifications, internal layout, etc. FAÇADE ENGINEERING: A NEW PERSPECTIVE Façade design in time In the 17th and 18th century a separation between design and engineering is evident while 20th century brings forward façade technology with the dissolution of the massive wall into a separation of structure and façade. Why this trend developed so fast? Increase in useable area and therefore profit (from massive to glass walls), self-weight facades with decreased foundations requirements, cost of glass versa other building materials, design industrialization (maintenance access paths and mechanical services intergraded in external façade appearance), architectural and technological evolution, market competitiveness…
382
Following this trend, façade engineering and consulting industry has, over a relatively short period of time, grown from an almost non-existent specialisation into a major growth area within the construction industry [1]. “Aesthetic appeal is no longer the primary consideration in modelling building envelope schemes. As façade design becomes increasingly complex, key factors such as performance testing, blast protection and the quest for genuine sustainability are more significant than ever” [2]. Private companies expand their consultation services through the development of façade engineering groups, market and consulting oriented or strongly linked to research and development (R&D) sectors. In addition to that, private consulting companies in UK have developed own façade simulation tools. Considering also that “insurance claims against architects involve the building envelope more often than any other building component” [5], façade design, construction and operation appears to be predominant in the building industry.
Fig. 1: Overlooking a listed building through a contemporary façade – the cohabitation of the history to the development [author’s photo]. Therefore, 60 years of curtain wall systems, 30 years of element façade systems, 10 years of experience with the integration of environmental services and double-skin facades, it could be considered the peak of optimisation! [6]. This asset provides a great perspective of further research and knowledge expansion in the actual performance of buildings façades, based on post occupancy evaluation studies. Façade performance: a rather difficult challenge How difficult or even impossible is to set directions on ‘How to design a building façade’ or even ‘How to operate a building façade’, as cases and criteria always differ (and should do so) according to culture and architecture, planning and legislative framework, economy and environment, building use, at local and national level? Additionally, how accurate can it be the level of impact of the façade in a building’s overall energy performance and indoor environment? The parameters affecting energy performance and indoor comfort are diverse and multidimensional, but is the façade and architectural design a predominant criteria as such? It is like looking back at the history of architecture and rediscover the importance of natural ventilation and lighting, and of thermal and visual comfort, rendered just by an integrated well designed building skin. It is like reminding that a building envelope cannot be a common and unchangeable pattern for all climatic conditions and urban contexts. Efficient envelope and façade design and performance over a building’s lifetime is a challenge in the building industry as contemporary procurement processes set high standards and performance indicators requirements in order to ensure optimum quality indoor environment with low operational costs. Complementary to that is the implementation of the Energy Certification processes through 2002/91/EC Directive in which energy (asset or operational) performance is interposed for a vast amount of the building stock. Classification approaches Façade classification seems to be important in view of proceeding to performance analysis and introduce energy and cost indicators. Various categorisations in other studies have been done for external claddings which are building use directed [7] [8], however it is a field that merit further
383
research in order to meet the diversity of architecture in non-domestic buildings. One approach of façade classification could be based on: § the appearance (modern or classical architecture) or § the cultural and architectural forms or § the type of materials used in the external walls and cladding (curtain wall, brick, metal, concrete) or § the proportion of transparent to compact surfaces (fully glazed, strip glazed, traditional) or § the area to wall ratio [6] with framed or load bearing structures or § the number of layers in the external skin (multi layer constructions) or § the inclination of the cladding, etc. Furthermore, another approach is the interrelation of external with internal environment, such as: § the air and light permeability, § the solar exposure, § the light and solar control systems, etc. Or even the adaptability potential and efficiency, mainly addressing to automations and controls. ENERGY REVIVAL THROUGH FAÇADE Energy performance and thermal comfort Façade design is related to architecture, culture, climate and social environment through forms, colors, materials. It is (or is should be) a highly dynamic and interactive element of the building, climate and user oriented. Introducing bioclimatic and energy design, passive and active elements are integrated in the façade design and are determined mainly by the form and characteristics of the building envelope, its orientation, its inclination, and its architectural features. Shading systems, sunspaces, openings, solar chimneys, green facades, PV panels and many others systems characterise a façade typology. However, especially for new buildings, it is not often easy to identify the climatic zone of a certain construction. Fully glazed buildings are seen in UK, France, USA, Greece, China, UAE. Technology is rapidly growing in order to meet thermal and visual requirements of construction components that greatly affect the heat, air and light exchange between the exterior and interior of a building. However, how the façade contributes into the permeability and ventilation in the contemporary architecture? Modern facades tend to be sealed due to: aesthetics, safety, fully controlled indoor environment requirements, local urban conditions regarding noise and pollution level, etc, often sacrificing the potential of maximum use of natural resources and microclimate dynamics. Façade refurbishment Building appearance is often requiring revival throughout its lifetime. Exterior surfaces now change every 20 years or so, to keep up with fashion, technology, regulations and standards or for wholesale repair. Therefore, in view of exploiting use of current building stock, major refurbishment often involves substantial reconstruction of building façades as a long term investment, either for aesthetic improvement and modernised appearance or for environmental compliances (urban pollution, external noise, unfavourable energy and visual performance). In isolated cases, only façade is retained and the whole rest of the building demolishes and reconstructed (mostly applied to cases where the building has historical significance and retention of façade is required). Parameters that affect positive decision making process towards façade refurbishment are: § potentially lower capital cost, shorter completion times, avoidance of planning constraints (exc. listed), embodied energy control (however, major refurbishment cycles are often frequent as 10 to 15 years for some building types, so the embodied energy value of these buildings may be almost as high as the energy used in occupying them over their real life-cycles), switching from AC to NV buildings (user control, climatic adaptation) and vise versa (organisational
384
prestige, standard requirements, deeper plans, claimed flexibility, higher rental levels giving a better rate of return, external traffic noise & dust). Accordingly, issues that could discourage major façade refurbishment interventions are: § structural and technical difficulties, lack of knowledge, cost increase during the process, nature of leases and high costs of waste in urban cities, retrofitting while occupied being rather expensive, owner-constructor-user difference. Therefore, technical, environmental and economic aspects need to be addressed and considered in a façade design and refurbishment process. ASSET PERFORMANCE OR OPERATIONAL BASED? Design to operation A building façade is determined in the design stage of a building project and some (or few) times is altered during construction and operation stage, revealing differences from the asset to operational building performance. The assumption made in the design stage, the construction changes, the operational chaos…few factors as such are indicatively summarized below. DESIGN STAGE
Assumptions – standards for the inner environment: might change in operation
internal temperature and humidity air velocity visual environment sound level
CONSTRUCTION PHASE
Client brief, cost constraints, lack of knowledge, design team not follow the construction
ventilation openings sealing passive (heating&cooling) systems elimination construction and material failures envelope quality specifications and standards
DESIGN TO OPERATION STAGE
Dynamic or simplified simulation tools: weakness to assess and define certain issues
actual draught effects from the building fabric (causing discomfort) surface temperatures & radiant temperatures from the surrounding elements (external or internal) thermal bridging effect moisture within the building components actual U-value of the building construction and certain lifetime
materials
after
building air tightness glare effects internal layout and uses changes related to façade perimeter as well as:
385
physiological and psychological factors (eg materials, colours) cultural aspects OPERATION STAGE
Building management and user behaviour
§ inexistent or insufficient or improper building management § users awareness, intervention in controls and systems
Fig. 2: Design, construction and operational risks that increase the asset to operational margin. The parameters mentioned above affect greatly the thermal and visual comfort of the users and could lead to a differentiated performance compared to asset targets, developing operational risks, increasing energy consumption or possibly adding extra costs to ineluctable façade interventions for user’s satisfaction. And in most cases, direct influences have mainly the adjacent to the façade zones. Therefore, the actual building construction, the building use and occupancy pattern, the users’ behaviour (in terms of habits, clothing, activity), the internal requirements and layout, could develop a scene much different to the expected one. Post occupancy evaluation surveys have been developed [3] [4] and further empirical data studies are needed in order to expand the knowledge on actual building and especially façade zone performance. This work will assist the evaluation of actual buildings comfort and energy performance and the validation of modeling and design tools. Operation to user’s interventions and expectations A building is either designed for its occupants or –often met – for its external surroundings and imaging. If users’ satisfaction is not succeeded, regardless its architecture (with exceptions to specific historic and monumental buildings), could be considered as a project failure. But, how is the inner space affected by the façade design? The internal layout is often influenced by façade construction as users might prefer to stand away from a fully glazed facade, feeling the direct solar radiation with glare and overheating effects and/or feel the draughts or radiant temperature from cold surfaces. Or even sit close to the windows for psychological purposes. Moreover, the type of the building skin influences internal layout in terms of resulted usable space. Choose thick or thin walls? It is discouraged to use thick external walls as “a study in Vancouver, British Columbia, showed that the square footage lost by using brick veneer instead of a thin cladding on an urban, high-rise condominium project could cost the developer up to $3.500 per unit in lost salable space” [5]. But, the space in a glazed façade perimeter can be actually used as office space or storage or other furniture fittings…? So what is actually the benefit in the inner layout and useable spaces of a lightweight construction? ECONOMIC PERFORMANCE AND BUILDING VALUE Economic Performance ‘Cost-effectiveness’ or ‘positive payback & cost-benefit ratio’ often comprise principle targets of a new or a refurbishment building project. In common practice, special consideration is given to the design and construction phase of a building, degrading emphasis on its operation. However, from facility management studies to commercial buildings, the operational, maintenance and refurbishment / replacement costs correspond to a percentage of 80-90% of the total cost in the lifespan of a building asset (depending of course on the life span for the building). Such indicator empowers the need to study and consider actual operational costs in a building’s overall lifetime, emphasizing on operational cost (energy, maintenance, cleaning, etc). Building Value A façade contributes to the value of a building….or not? Quantity surveyors consider as main criteria
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for valuing a property, the area, the location and the age of the building. The envelope is indirectly embedded to the value of a building through its architectural appearance, even if in cases an old building fabric might have better performance than a new one. However, subjective criteria for property valuation and building preference might differ from public to private sector and according to the type of use. The energy performance certificate (asset or operational) introduced by the Energy Performance Building Directive 2002/91 gives a new perspective on the ‘value’ of the building fabric through the energy performance of the building as a whole. At EU and national level, emphasis is given to the existing building stock that immerge improvement though interventions in the fabric and services. Extended interventions in fabric leads to high cost investments with long payback periods, affecting directly building owners. Therefore, economic viability of such investments is required. Demolish or retain? Need the minimum cost interventions with the higher energy performance improvement? Financial market (and tax structure) frequently encourages short term view investments. Therefore, long term efficiency benefits -which often occur from fabric improvements (with long physical life)- are sacrificed for the short term gains offered by increase heating and/or cooling system efficiency. Although, it need to be considered that decisions concerning the appraisal and allocation of resources to buildings and civil engineering projects take place in a relatively long time frame [9]. In terms of construction cost, the façade of the building can account for between 15% and 40% of the total building budget [10], and may be a significant contributor to the cost of up to 40% more through its impact on the cost of building services. Life Cycle Costing (LCC) LCC is an important tool in use to facilitate choices where they are alternative means of achieving the client’s and stakeholder’s requirements, based on costs over the lifetime of a building. Applying LCC in the early stage of a building by testing and evaluating different design and construction scenarios strongly encourages the construction and use of energy efficient and environmental friendly constructed assets. Furthermore, decisions, data feedback and continual monitoring and optimization of LCC must proceed throughout the life of the project. Therefore, based on the results of LCC analysis, the building owners and planners are able to optimise the overall performance of a building and make founded decisions for the further process, as well as facilitating more robust levels of comparative analysis and cost benchmarking for different façade options. Moreover, budgeting investment options in accordance to expected building performance is a key variable firmly embedded in public procurement processes and several financing tools (ESCO’s, TPF, PPP, etc) across Europe. This sets higher standards on façade design and performance requirements, as well as benchmarks in respect to energy performance and costs of operation and maintenance of a construction asset within its whole life. The main burdens to apply LCC analysis is often the lack of real buildings’ cost data and lack of time in design process. Ground work regarding data collection on cost indicators for buildings, especially in the non-domestic sector, has been developed within an EU IEE project titled LCC-DATA [11], in which various difficulties appeared on collecting, storing and accessing the data. However, related costs on façade elements merit significant research. Concluding, exploitation of LCC practice will assist investors and building owners to have an increased role in decision making process, taking account of the running costs (operational & maintenance) of buildings’ infrastructures over a long lifetime and assessing the environmental and economic efficiency of certain asset investments. Building Façade and Maintenance The role of the professional building owners and facility managers is considerable in the development of the building and construction market, and LCC analysis contribute to the evaluation of different steps of building or refurbishment processes, based on an economic investment analysis, even looking at the building as a whole or at façade scale. For example, clients of public buildings require a
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building life expectancy of about 100 years while selected cladding can have 15-20 years. Especially addressing a façade element which is exposed to vandalism, weather severities – sun/snow/wind/water, high pollutants, etc, is important to consider issues of maintainability and operation in its lifecycle. For example, the regular cleaning of the whole of the exterior of the Canary Wharf Tower in London is approximately £200k per annum, employing 8 people continuously, with the pyramid on the top being cleaned on an annual basis at a cost of around £4k [12]. Hence, do actually architects design based on a projects’ life expectancy? Or even to the provision of easy cleaning and/or maintenance of the façade elements? It is a very important criteria in the final decision of a certain envelope type, parameter that is often overlooked. SURVEY AND MONITORING STUDY How people perceive façade design and performance In the framework of this study, a questionnaire has been developed and addressed to building industry related groups with the aim to trace people’s perception on façade design and performance. From a sample of 60 completed questionnaires, the following trends could be identified developing a further ground of research: § Façade versa building systems’ significance is kind like architects versa mechanical engineers. § Location convenience (and internal layout) surpass energy standards as priority. § In theoretical basis, energy criteria prevail but in practice architectural appearance, cost, specs and client brief determine façade construction. However, the preference for energy efficient buildings is highlighted. § Glare and overheating appear as main problems for glazed façades. § Façade performance has greater impact to open plan versa cellular layout buildings. § Façade construction and materials affect significantly external environment / microclimate. § Mechanical engineering groups support that natural ventilation through the façade is very difficult or even impossible, especially in a city centre. § User interacts with the façade and the façade affects the user. § Façade refurbishment is burdened due to occupation, cost and construction risks. § Poor design, energy performance, construction and maintenance are often addressed as main façade problems. § Façade design criteria change according to building use. Monitoring study One-year monitoring study in three office buildings in London area is in progress in terms of detailed recording of indoor conditions with emphasis on façade zone. A principle aim of the study is to understand the indoor conditions of the perimeter façade zone related to temperature and thermal comfort, recording temperature and humidity on a dense vertical and horizontal grid. The case study buildings have the characteristics as: Façade Typology
Ventilation mode
Date of construction
A
fully glazed construction
Mixed mode
50s’ - totally renovated in 2003
B
striped glazing
Fully A/C environment
Constructed in 2008
C
masonry construction
Nat vent
Grade II listed (more than 100yrs old)
Preliminary results show that temperature difference between the façade layer and the inner zone (up to 3m away from facade) could reach 2-3oC in a fully glazed façade in early autumn period. This difference might indicate local discomfort conditions close to the façade area and could result to higher energy consumption of the building overall and also to provide useful information in terms of A/C
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systems positioning along the façade zone. Vertical temperature distribution, especially in low height ceiling offices, does not significantly vary but will be further investigated in relation to building and façade typology, mechanical systems type, etc. Another issue that has been identified is the local discomfort that might appear in office desks close to staircases and atriums, due to temperature stratification and vertical air movement draughts. However, even if the perimeter zones of a building are often directly exposed and subjected to the external climatic conditions, the preference of the users in these areas is often recorded.
CONCLUSIONS AND FURTHER RESEARCH The façade is part of the building envelope and its design and efficiency is a critical determinant on decision making processes affiliated with long term energy, environmental and economic building performance. Current prescriptive based techniques are no longer adequate and it is widely acknowledged that performance based analysis is an enhanced solution for building and façade analysis. Furthermore, it is critical to explore environmentally and economically sound design and development techniques in order to design buildings and infrastructure that are sustainable and healthy, and encourage innovation in decision making process, considering both infrastructure design and efficiency of use. This research has been progressing in order to explore empirical detailed monitoring data from existing UK office buildings, aiming to understand the energy and economic performance of building facades. Emphasis is given to energy consumption to be highly compared with design intent and whole building life cycle performance to apply for new and refurbishment building projects. In addition to that, it aims to identify and justify parameters that affect the working and built environment (inner and outer) related to the building façade and provide information useful to construction decisions. Results obtained will assist investors and building owners to have an increased role and integrated approach in decision making process, taking account of the running costs (operational & maintenance) of buildings’ infrastructures over a long lifetime. ACKNOWLEDGEMENTS This research project is being funded by the Engineering and Physical Sciences Research Council (EPSRC) in UK, in the framework of Carbon Reduction in Buildings (CaRB) project and in cooperation with the Bartlett School of Graduate Studies, University College London. Carb project is a multiuniversity research project funded by the EPSRC and Carbon Trust as part of Carbon Vision Buildings (CVB).
References [1] Karsai, P. (2004). Façade procurement: the role of the façade consultant [2] Society of Facade Engineering, http://www.facadeengineeringsociety.org [3] Bordass, B. (2001), Final report FLYING BLIND: Everything you wanted to know about energy in commercial buildings but were afraid to ask, Association for the Conservation of Energy, www.ukace.org [4] Probe project: Post-occupancy review of buildings and their engineering (1995-2002) [5] Brock, L., Hoboken, N.J, Wiley, J., (2005), Designing the exterior wall: an architectural guide to the vertical envelope. [6] Brookes, A., Meijs, M., (2008), 4th edition, Cladding of buildings, Taylor & Francis, London [7] Steadman, P. and Bruhns, H. (1997). Non-domestic building stock project / Final report [8] Kolokotroni, M., Robinson-Gayle, S., Tanno, S., Cripps, A. (2007). Environmental impact analysis for typical office facades [9] Raftery, J. (1991). Principles of building economics book
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[10] Hall A., ARUP (1997) [11] EIE/06/154/SI2.447798, LCC DATA: Life-Cycle-Costs in the Planning Process. Constructing Energy Efficient Buildings by Taking Running Costs into Account, SAVE EIE, 2007, project coordinator: SINTEF/Norway [12] Johnson, P., (2001), The Cleaning & Maintenance factor, The Whole-life performance of facades – Proceedings
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IEECB'10 - Building Energy Rating & Commissioning
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Signs of Hope? Emerging trends in European Building Performance from an analysis of DISPLAY Richard Bull, Ashish Shukla, Graeme Stuart Institute of Energy and Sustainable Development, De Montfort University.
Abstract The European DISPLAY campaign is a voluntary scheme aimed at encouraging local authorities to publicly display the energy and environmental performances of their public buildings (http://www.display-campaign.org/). The label is similar to that already accepted on European Union electrical appliances. The rating is from A-G with A being most efficient, or preferred. Buildings are rated according to primary energy consumption, greenhouse gas emissions (mainly Carbon Dioxide) and water consumption. The underlying hope is that participating in the DISPLAY certification campaign will lead to significant improvements in the energy performance of municipal buildings. The Institute of Energy and Sustainable Development, based at De Montfort University in Leicester (England) has analysed the trends in energy performance across participating municipalities. Encouragingly the clear trend over time is that there has been an increase in the number of A rated energy certificates issued, and a steady decrease in the number of both F and G rated energy certificates. However, the emphasis of this paper will be on the improvements and deteriorations experienced by specific buildings. Having assigned a numerical value to each ‘grade’, two methods have been identified to measure the effectiveness of efforts to improve building energy performance. This paper discusses the merits of these methods of analysis, the emerging trends highlighted by our initial analysis and poses further research questions surrounding the merits of the certification process and the potential for improving energy performance across municipal buildings.
Introduction We shape our buildings; thereafter they shape us". Winston Churchill If national and local governments are serious about tackling increasing carbon dioxide (CO2) emissions believed to be contributing to our changing climate then sooner or later emissions from buildings must be tackled. A building is not just bricks and mortar, steel and concrete. Buildings are a statement of what we believe, what we value and how we view the world. Currently, in the UK for example, buildings constitute 40% of UK carbon emissions, with non-domestic stock accounting for 24 roughly half of that. In order to sense clearly the story our buildings are saying about us we need to be able to listen and understand with accurate hearing. This paper is explores what buildings are saying by analysing information gained as a result of the Energie-Cites project: the DISPLAY campaign. The European DISPLAY campaign is a voluntary scheme, started by Energie-Cites25, aimed at encouraging local authorities to publicly display the energy and environmental performances of their public buildings.26 With the European Union legislation on buildings and energy services, and the widespread adoption of energy labels for electrical appliances, there is a need for municipalities to demonstrate their commitment to energy efficiency by displaying an energy label on their buildings. The label is similar to that already accepted on European Union electrical appliances. The rating is from A-G with A being most efficient, or preferred. Buildings are rated according to primary energy consumption, greenhouse gas emissions (mainly Carbon Dioxide) and water consumption. A key part of the rationale for developing the energy display label was to motivate decision makers towards a common approach for European certification for energy performance of non-residential buildings and engage municipal energy managers and the general public around the subject of energy and 24
According to the Carbon Trust 2008
25
Energie Cites is a European network of municipalities created in 1990 and now representing over 1000 towns and cities across 26 countries. 26
http://www.display-campaign.org/
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buildings. Energie Cites has produced a number of promotional tools including leaflets, a website and a communication handbook. These are available in 16 languages. Its website provides opportunity for the public to access information about the project. It also has a restricted domain where Energy Cites members can access their display data and generate posters. It includes mainly three functions: a calculation tool, a monitoring and bench marking tool, and a tool to encourage dialogue between decision makers, municipal experts and the general public. The underlying hope is that participating in the DISPLAY certification campaign will lead to significant improvements in the energy performance of municipal buildings. To date over 22,00027 energy-rating certificates for different types of dwellings were issued by the 28 participating European nations from 2001 to 2009 for a total of 10,522 buildings (Fig 1). Figure 1 (a) Number of certificates issued in different countries (countries having less than 100 certificates are excluded) (b) Percentage of different types of buildings involved in certification (a) (b)
The Institute of Energy and Sustainable Development, based at De Montfort University in Leicester (England) has analysed the trends in energy performance across participating municipalities. Encouragingly the clear trend over time is that there has been an increase in the number of A rated energy certificates issued, and a steady decrease in the number of both F and G rated energy certificates. This paper discusses the broad trends in the merits of these methods of analysis, and the emerging trends highlighted by our initial analysis and poses further research questions surrounding the merits of the certification process and the potential for improving energy performance across municipal buildings.
Energy and Buildings – policy and literature background The building sector consumes roughly one-third of the final energy used in most of the countries, which represent about 40% of the gross energy consumption in Europe [1]. During the past few decades governments in various countries have initiated policies to reduce energy consumption in buildings. Most of the policies lie in the main three categories: economic incentives, informational programmes and regulatory requirements. Economic incentives include taxes and energy pricing; informal programs include energy awareness campaigns and energy audits; regulatory requirements include codes or standards. Most EU countries have legislation at the national level although there may be additional local laws as well. For member states of the EU, legislation is being driven by EU laws e.g. Energy Performance of Buildings Directive (EPBD), having freedom of local implementation of building codes. National regulations have to follow the concept of the EPBD and need be harmonized as much as possible [3]. The Buildings Energy Performance Directive (EPBD) was approved on 16 December 2002 [4] and brought into force on 4 January 2003. The principal objective of the Directive was to promote the improvement of the energy performance of buildings within the EU through cost-effective measures. There are four main aspects to the EPBD. 27
th
Using data downloaded from the Energie-Cites website on October 28 2009,
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1) Establishment of a calculation methodology: Member States must implement a methodology for the calculation of the energy performance of buildings, taking account of all factors that influence energy use; 2) Minimum energy performance requirements: there must be regulations that set minimum energy performance requirements for new buildings and for large existing buildings when they are refurbished; 3) Energy performance certificate: there must be an energy performance certificate made available whenever buildings are constructed, sold or rented out; 4) Inspections of boilers and air-conditioning: there must be regulations to require inspections of boilers and heating systems (or an alternative system of providing advice as discussed below), and inspection of air conditioning systems. Implementation was subsequently much harder than first realised. Lack of implementation across Europe and confusing interpretations led the proposed ‘recast’ which was finally agreed in Nov 2009 which sets ambitious targets for the future of public buildings. For example, as of 31 December 2020 new buildings in the EU must consume 'nearly zero' energy and the energy will be 'to a very large extent' from renewable sources. The recast also calls for a more detailed and rigorous procedure for issuing energy performance certificates in member states. This clarity is welcome given the diversity, standards and labelling schemers that exist around the world such as R2000 (Canada)28, LEED (USA)29, MINERGIE (Switzerland)30, BREEAM (UK)31 and many others. The energy standards for buildings in various countries are in different stages e.g. mandatory, voluntary, and proposed for different building sectors. Janda, 2008 [2] made a survey of these standards for 80 countries worldwide. They reported that 59 countries have some form of mandatory or voluntary existing standard, twelve countries had proposed standards and nine countries did not have standards (Figure 2). Informal programmes deals with awareness and user engagement for the reduction in energy demand. Various energy initiatives aim to support the work of actors 32 33 working at local and regional level. ManagEnergy , Sustainable Energy Europe campaign , 34 35 European Greenlight programme EU Energy Star programme , Association for the Conservation of Energy36,Energie Cités37, European Sustainable Energy Education Forum (ESEEF)38, Kids for Energy39, UK Centre for Sustainable Energy40, Alliance to Save Energy41 and Display-campaign42 are various energy initiatives programs going on at local level or EU level. The European Display Campaign is a voluntary scheme designed by energy experts from European towns and cities. As most of member states have a national certificate for their exiting public buildings, Display is increasingly being used as a complementary communication tool. Figure 2 Worldwide status of energy standards for buildings43
28
http://r2000.chba.ca/What_is_R2000/index.php
29
http://www.usgbc.org/DisplayPage.aspx?CategoryID=19
30
http://www.minergie.com/home_en.html
31
http://www.breeam.org/
32
http://www.managenergy.net/
33
http://www.sustenergy.org/
34
http://www.eu-greenlight.org/
35
http://www.eu-energystar.org/en/
36
http://www.ukace.org/pubs/reports.htm
37
http://www.energie-cites.org/
38
http://www.school4energy.net/
39
http://www.kids4energy.net/
40
http://www.cse.org.uk/
41
http://www.ase.org/greenschools/
42
http://www.display-campaign.org/
43
(Source: Janda, K.B. Worldwide status of energy standards for buildings: A2007 update, In proceedings of the Fifth Annual IEECB Frankfurt Germany, April 9-10, 2008)
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Methods of Analysis
For the Energie-Cites DISPLAY database, over 2200044 energy-rating certificates were issued by the 28 participating European nations between 2001 and 2009 for a total of 10,522 buildings. Countries such as France and Great Britain have issued the majority of certificates (Figure 1), with Czech Republic, Ukraine and Finland following close behind. Why certain countries have been faster to respond and issued more certificates is raised as an interesting research question to be discussed in subsequent reports where we will consider the role of local, national and European policy on DISPLAY. The emphasis of this report will be on the improvement made by specific buildings. To gain a more meaningful picture of what has happened over recent years we need to consider the trend over time. Figure 3-5 (below) highlights this.
44
th
Using data downloaded from the Energie-Cites website on October 28 2009,
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Figure 3: The graph shows the Energy rating certificates issued from 2001-2009 for each rating.
Encouragingly the clear trend is that there has been an increase in the number of A rating energy certificates issued, and a steady decrease in the number of both F and G rating energy certificates. In fact the result shows an increase in the number of energy certificates issued relating to the energy rating of A, B,C and D. However, the number of A certificates being issued is still a low percentage of the total number, the majority of certificates issued are C and D (Figure 3). Figure 2 also still shows that whilst the trend for G ratings is decreasing, the number of G certificates being issued is still high. For energy rating maximum increase observed for B and C rating certificates during 2001 to 2009 (approx 10 % increase). Continuous increase in A certificates for CO2 during 2001 to 2008 while there is downward trend observed in 2009 (Figure 4). The decrease in G certificates for CO2 is not as significant as observed for energy certificates. The percentage share of A certificates has continuously increased for water though demonstrating higher share of G ratings and B ratings as well (during 2009). Figure 4: The graph shows the percentage of CO2 rating certificates issued from 2001-2009 for each rating.
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Figure 5: The graph shows the water rating certificates issued from 2001-2009 for each rating.
Methodologies to identify improvement: from certificates to buildings Central to our analysis is whether or not buildings have improved their performance as a result of their involvement in the DISPLAY campaign. The hope of the campaign has always been that as a result of displaying the DISPLAY certificate, and through undertaking communication with building users, that building performance improves and energy consumption decreases. This question will be addressed through research into building users as a result of this initial analysis, first we need to identify which buildings have changed their usage so they can be researched. The aim is to identify which buildings have either improved their energy ratings or actually deteriorated during the course of the DISPLAY program. For this analysis a methodology has been developed to assess the changes that have occurred during the course of the campaign. Each building’s energy rating certificates will be used to establish its progress. This is a move from analysis of certificates to an analysis of individual buildings. Two methods have been identified that would enable this analysis. The first method is based on a comparison between the best and worst performing certificates while the second method compares earliest and latest. To do this a core metric could be designed to represent the effectiveness of efforts to improve building energy performance, based on the progression of display energy ratings for a given building over time. In order to capture the overall success irrespective of when changes were made, the metric would be based on the entire period of available data. Rating are provided between A to G, where A is highest possible rating achieved by the building and G lowest. Ratings given a numerical value in ascending order with incremental value of 1 starting from lowest building rating (G).
Method 1 Using this methodology, for each building with two or more certificates issued, the best (max) and worst (min) energy ratings are determined. The absolute difference between these ratings is calculated to indicate the magnitude of change. This is multiplied by a factor (• ) to determine the sign, -1 is used if the best certificate was issued before the worst, 1 is used otherwise.
∆ = σ max− min
(where • = -1 if best certificate was first and • = 1 otherwise) The resultant metric, • represents the change in rating experienced by the building. Negative values indicate deterioration, positive values indicate improvement. It has been calculated for each building where two or more certificates were issued. An analysis of these values forms the basis of the remainder of this report. For example A building has highest energy rating certificate of “B” in 2004 and drops to its lowest energy rating certificate of “E” in 2007. The overall rating for the building is 1*(6-3) Rating = -3. Method 2 For the second method the earliest and latest certificate available is used
∆ = (latest − Earliest)
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if the earliest certificate is of higher rating e.g. “A” (numeric value 7) in year 2001 and latest rating is in year 2008 and is “E” (numeric value 3). The movement in rating calculated will be -4 (Latest-Earliest) and if the case is vice versa it will be +4. Negative movement in rating implies deterioration over time. This metric highlights changes in building energy certificate ratings. It is beyond the scope of this report to investigate why these changes occur, that is for phase 2 of the research. However, some basic research questions will be posed in the conclusions. The maximum movement, from “G” to “A” or from “A” to “G”, is equivalent to +6 and -6 respectively. As expected this is quite rare within the database. Smaller movements are more common and the most common scenario is that a building retains the same rating for all issued certificates (a movement of zero). Buildings having only one certificate are excluded for analysis for both the aforesaid methods.
Emerging Trends in Municipal Buildings Using first methodology would yield the following results – see figure 6. It is clear that (Figure 6) more buildings have improved than deteriorated and that many have stayed constant in their energy rating. In fact, 2021 (41 %) buildings have improved their energy ratings, 1040 (21.0 %) buildings have decreased and 1875 (38.0 %) buildings have seen no change. The trend is more or less same for CO2 whereas it differs slightly for water ratings. Only 1604 (32 %) buildings have improved their ratings, 1359 (28.0%) buildings have decreased and 1973 (40 %) buildings have seen no change for water ratings. With a movement metric for each building in the database it is a simple process to produce aggregate statistics for organizations and countries. Figure 6: The figure shows the movement histogram of buildings with their relevant energy performance (the results were obtained by the first method)
However, there are some problems with this methodology – identify – for example; a building could go up or down. For the purposes of this report it helps us to see the overall trajectory of a building over time. The main reason for using the second method (earliest and latest ratings considered for analysis) is that this provides updated information with respect to change occurred in performance of building. Therefore it is possible to take the first and latest certificate rating and conduct an analysis this way. Figure 7 below shows the results using second method. Figure 7: The figure shows the movement histogram of buildings with their relevant energy performance (the results were obtained by the second method)
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Figure 7 shows the movement histogram for energy, CO2 and water rating by second method. Again the maximum numbers of buildings are different for all type of buildings (49 % for energy, 52.2 % for CO2 and 50.5 % for water). The maximum increase for improved ratings (positive movement) is observed for energy ratings (35.0%), least for water ratings (27.3 %) and for CO2 ratings 31.3 % buildings show improvement. Deterioration in ratings is found maximum for water ratings 22.2 % whereas energy and CO2 are close to 16 % of total buildings. This analysis can lead us to identify which countries have seen an increase in their building stock performance and those that have not (Figure 7). Table 1 gives average score for different country for Energy, CO2 and water ratings. Buildings with only one rating certificate during 2001 to 2009 are excluded while calculating the average score. Poland leads the tally for improvement in ratings for energy and water where as far behind if we talk about performance of water ratings. It is quite clear that countries having high (or + score) for energy have the same for CO2 but not for water, this is a further point of consideration when making detailed study based on survey results. The countries having fewer number of buildings registered are found to perform quite well with comparison to countries with a greater number of registered buildings – is this because of motivation, government policy, or effective showcase for DISPLAY campaign and engagement of occupiers for improvement of building performance – future building research will hopefully shed light on this.
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Table 1: Chart detailing overall improvements of buildings45
Research Concerns The research undertaken has exposed some fascinating issues related to municipal buildings and energy – one in particular that we wish to highlight is the extent to which energy consumption of a building depends on climate conditions which are vary for one certain geographic region over the years, and how that is measured. The ‘weather correction factor’ provides a means of correcting the consumption data for the local climate otherwise it would not be possible to compare the results of one building across the different years. In order to include a weather correction factor the final energy that is used for space heating is multiplied by the weather correction factor. After this step, the total climate corrected final energy consumption of the corresponding energy source is multiplied with the specific CED or KEV factor.46
Figure 8: Structure of the calculation tool
45
Austria, Denmark, Estonia, Luxembourg, Sweden and Slovenia each have no buildings issued more than one certificate at the time the data were collected and so do not appear in the table. 46
The CED factor is defined in the German guideline VDI 4600 and refers to the sum of all primary energy inputs of a product or a service including its production, usage, and disposal. ‘KEV’ refers to the cumulative energy use factor, i.e. the overall primary energy consumption which is linked with the creation or use of a product or a service, including all preproduction chains but without primary energy used materials such as mineral oil in plastic products (http://www.displaycampaign.org/doc/en/index.php/GLOSSARY)
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The result is the associated primary energy consumption. Thus, a weather correction factor larger than one represents a relatively mild winter and simulates an increase in the amount of energy consumption of the building. This is necessary as the building would have consumed more energy under average climate circumstances. As a result, the different energy consumption ratios are comparable over the years. The statistics of weather correction factor of available data for buildings during 2001-2009 in various countries is given in figure 13. The value of the weather correction factor varies from 0.694 to 1.47 whereas average value is 1.032. Approximately 9,000 buildings are found to have weather correction factor value of 1.0 (this may be default value while no input have been given for weather correction factor). Buildings having weather correction factor less than 1 are nearly 3579 in number, whereas 9471 buildings have weather correction factor greater than 1.0.The value of weather correction factors for UK buildings in most of cases are found to be 1.1 or 1.11 in consecutive years. Concern has been expressed that the repeated entry of this figure implies an inaccuracy or default setting and as a result could affect the quality of the data. To that end we have run a cross check against the actual climatic figures. Cross checking of weather correction factor for UK buildings: Weather correction factor=DD average/DD reference Table 2: Showing weather correction factor in different region of UK (Degree days data are used from http://www.carbontrust.co.uk/resource/degree_days/what_are.htm) S.No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Region London(Thames Valley) SouthEastern Southern SouthWestern SevernValley Midland WestPennines NorthWestern Borders NorthEastern EastPennines EastAnglia WestScotland EastScotland
2009 1.013439 1.053259 0.997317 0.986963 0.88641 1.003137 0.933452 0.969239 1.061224 1.013182 1.02805 1.0089 1.038012 1.037016
2008 1.00279 1.012689 0.964762 0.978434 0.911943 0.988272 0.920996 0.940064 1.00085 0.985476 1.013986 0.994531 0.982406 0.987689
2007 1.135135 1.073196 1.070259 1.152406 1.009583 1.084403 1.053615 1.079777 1.080549 1.098189 1.132987 1.099648 1.105991 1.079965
2004 1.098895 1.056962 1.174833 1.074895 0.989746 1.129191 1.103397 1.120448 1.121671 1.09016 1.130911 1.077619 1.103234 1.111545
401
15 16 17 18
North East Scotland Wales Northern Ireland NorthWestScotland
1.041939 0.990378 1.071429 1.092113
0.998826 1.009833 1.003991 0.995966
1.088586 1.118221 1.123328 1.090548
1.097794 1.082157 1.065999 1.095908
Comparison of weather correction factor in different years for UK: For Bristol city council (zone 5) calculated value of weather correction factor is 0.88641 where as from DISPLAY the actual value is 0.95 for 2009. For the same year in Durham city council (zone 10) calculated value of weather correction factor is 1.013182 where as from DISPLAY the actual value is 1 and in Leicester (zone 6) calculated value of weather correction factor is 1.0 where as from DISPLAY the actual value is 1.11.For 2008 comparisons have been made for different council buildings. For Nottingham City Council (zone 11) calculated value of weather correction factor is 1.013986 where as from DISPLAY the actual value is 0.895609319. For Nottingham city council some time weather correction 0.8109 is also used. Lewes District Council (zone 2) calculated value of weather correction factor is 1.012689 where as from DISPLAY the used value is 1.0. Durham city council (zone 10) calculated value of weather correction factor is 0.985476 where as from DISPLAY the actual value is 1. Derby City Council (zone 6) calculated value of weather correction factor is 0.988272 where as from DISPLAY the actual value is 1.0 The comparison is also made for earlier years of Display campaign during 2004. Durham County Council (zone 10) calculated value of weather correction factor is 1.09016 where as from DISPLAY the actual value is 1.1. Sometimes value used is 1.1595. Derby City Council (zone 6) calculated value of weather correction factor is 1.129191 where as from DISPLAY the actual value is 1.0. Bristol City Council (zone 5) calculated value of weather correction factor is 0.989746 where as from DISPLAY the actual value is 1.02 As a result of this cross checking of values for UK it can be seen that sometimes both calculated and used values are similar or quite similar but some time there is significant difference. Values which are 1.0 or 1.11 are sometimes close to calculated weather correction factor but sometimes they are not. It is not possible to filter the values which are 1 or 1.11 as sometimes they are correct. Sensitivity Analysis: To further analyze how the weather correction factor affects the rating of buildings, sensitivity analysis has been carried out. Local sensitivity analysis investigates the changes in a model output with respect to small changes in models input parameters. The sensitivity is normalised with numeric value of earliest rating and average weather correction factor.
Si, j =
Wavg ∂R Ri ∂W
Where W avg is average weather correction factor, Ri is earliest building rating (numeric value). The values are shown in graphs given below.
402
Figure 9: Number of buildings having local sensitivity equal to zero, less than and greater than zero.
Figure 10: Scatter graph for local sensitivity for weather correction factor.
Local sensitivity analysis shows that most of the buildings rating are unaffected by change in weather correction factor but others do change. But this is difficult to quantify that the changes occurred in building ratings are only because of change in the weather correction factor or how much their involvement exits to change the building rating. As per cross checking of UK buildings for weather correction factor it seems that the weather correction factor used are quite accurate and there is no need to make another filter for weather correction factor based on their values.
Conclusion and outline of the next stage This initial review paper has laid out the current picture of DISPLAY certificates across Europe. These figures are a very useful guide to help pick out areas of interest. However, in many cases they may be misleading. Deterioration in energy ratings may have causes which are uncontrollable. However, the scores do provide an indication that conditions are more favorable in some countries than in others. Further research is needed into the causes of these patterns of data, and to do that further research is ongoing as part of DMU’s work with Energie-Cites. This year we will be targeting specific organizations and buildings to uncover detail about the context in which these results are to be interpreted. We aim 403
to firstly, obtaining detailed statistics on specific buildings – i.e. which buildings have improved, in which municipality and country; and second, to gather detailed information on how these buildings are operating, what technical improvements have been made, what local and national policy contexts are they operating within and so on. Fascinating questions remain unanswered as to what actually drives building performance – technical improvement or building user behaviour – possibly. For now it is clear that the patterns of building energy consumption are changing, for the better. Whether the changes are happening quicker enough is another matter. It is hoped that as part of the next stage of our research there will be more answers to questions, and no doubt, more questions. References [1]
Balaras A.C., Drousta K., Dascalaki E and Kontoyiannidis S. Heating energy consumption and resulting environmental impact of European apartment building, Energy Build 37 (2005), pp. 429–442.
[2]
Janda, K.B. Worldwide status of energy standards for buildings: A2007 update. In proceedings of the Fifth Annual IEECB Frankfurt Germany, April 9-10, 2008.
[3]
Szalay A.Z. What is missing from the concept of the new European building directive?, Build Environ 42 (2007), pp. 1761–1769.
[4]
European Union, On the Energy Performance of Buildings. Directive 2002/91/EC of the European Parliament and of the Council, Official Journal of the European Communities, Brussels, December, 2002.
404
The Future of Building Energy Rating and Disclosure Mandates: What Europe Can Learn From the United States Andrew Burr1, Cliff Majersik1, Nick Zigelbaum2 2 Institute for Market Transformation, Natural Resources Defence Council
1
Abstract Worldwide, commercial building energy rating and disclosure mandates are becoming more common as policymakers target the building sector in energy and climate protection policies. Although the United States has no policy equivalent to the European Union’s Energy Performance of Buildings Directive (EPBD), rating and disclosure policies are beginning to appear in states and local jurisdictions. This paper will explore the details of policies related to the rating and disclosure of building energy performance enacted in the United States. In the absence of a federal mandate, states and jurisdictions are experimenting with different approaches to building energy rating and how that information is conveyed to the market. The paper will discuss specific approaches and strategies that have the potential for integration into European policies. Although U.S. rating and disclosure policy is less expansive than in Europe, research based on the voluntary rating and disclosure of U.S. buildings suggests the U.S. marketplace is already factoring energy efficiency into its real estate decision-making. This paper will discuss findings from leading academic institutions that conclude energy-efficient properties in the United States have greater occupancy levels and higher lease rates and sale prices than less efficient properties. These trends will likely accelerate as more buildings are rated and more ratings are disclosed, while also exerting pressure on less efficient buildings to engage in energy retrofits.
Introduction In confronting climate change, nations around the world are searching for effective policies to reduce greenhouse gas emissions. Improving the energy efficiency of buildings, which account for nearly 40 percent of global energy demand and an almost equal share of greenhouse gas emissions, has become a chief goal of policymakers in many countries [1]. In the United States, commercial buildings account for roughly 19% of energy-related carbon dioxide emissions (See Figure 1). As such, policymakers are becoming more attuned to building energy performance rating and disclosure mandates. These mandates are primarily aimed at existing buildings, which comprise the vast majority of the building stock and present the largest opportunity for reductions in energy and greenhouse gas emissions. In New York City, 85% of existing buildings today will still be in use in the year 2030 [2]. More than 30 countries around the world now have some form of mandatory building energy rating policy [3].
Figure 1: U.S. Energy-Related Carbon Dioxide Emissions by End Use Sector, 2008
Transportation, 33%
Industrial, 27%
Buildings, 40%
Residential, 21%
Commercial, 19%
Source: U.S. Energy Information Administration The United States has become very interested in building energy rating and disclosure within the past five years as a tool to help the marketplace value energy efficiency, encourage building energy retrofits and reduce energy consumption and greenhouse gas emissions. Although the United States has no federal policy equivalent to the European Union’s Energy Performance of Buildings Directive (2002/91/EC), which mandates building energy performance rating and disclosure to all EU Member States, U.S. states and local jurisdictions have begun to enact rating and disclosure requirements for commercial and residential buildings. The absence of a federal policy has allowed states and jurisdictions to experiment with different strategies, yielding many innovative approaches. Those approaches include: • • • • • •
Requiring building performance rating and disclosure at regularly scheduled intervals Requiring building performance rating and disclosure prior to a real estate or financial transaction Reporting building performance information to government Posting building performance information on a public web site Disclosure of building performance information to current tenants and prospective lenders Requiring improvements to buildings following performance rating Setting minimum rating standards for government leases
Some of these strategies are built into the EPBD, although many are not. As such, there are opportunities for EU Member States to implement strategies from U.S. policies to augment the requirements of the EPBD and strengthen their building energy certification platforms. In some cases, Member States are already implementing strategies above and beyond EPBD requirements. Although rating and disclosure mandates are a recent development in the United States, commercial real estate research strongly suggests that leasing and sales transactions are already influenced by the energy performance of buildings. According to multiple studies, energy-efficient buildings achieve higher occupancy rates, rental rates and sale prices than comparable, less-efficient buildings, increasing their property value. These findings are an important consideration in determining the effectiveness of rating and disclosure mandates as a strong market force.
U.S. Building Energy Performance Rating and Disclosure: State/Local Policy Snapshot Two U.S. states, three major cities and the District of Columbia have enacted legislation mandating the measurement and disclosure of privately owned, commercial buildings (See Table 1). Legislation is pending or was previously proposed in several other states, including Maryland, Oregon and Illinois. Additionally, Arlington County in the Commonwealth of Virginia is voluntarily measuring and posting the energy performance of its owned and leased real estate to a public web site. 406
Table 1: United States Building Energy Rating and Disclosure Policies Building types
Disclosure
Also required
California
Nonresidential
Point of Transaction: Buyers, lessees and lenders
Utility assistance
District of Columbia
Nonresidential
Annual to public web site
Disclosure of energy use estimations for new buildings 50,000 SF+
Austin, TX
Point of Transaction: Energy audits for multifamily Nonresidential Buyers + public display buildings + retrofits for + multifamily for multifamily inefficient multifamily buildings buildings
Utility assistance; mandatory audits & Point of Transaction: Washington retrofits for inefficient Nonresidential Buyers, lessees and State public buildings + lenders minimum ratings for state leases Nonresidential multifamily
+
Seattle
Nonresidential multifamily
+
Arlington County, VA*
Public
New City
York
Annual to public web site
Energy audits & retro commissioning; mandatory retrofits for inefficient public buildings
Point of Transaction: Buyers, lessees and lenders + current tenants + annual to city
Utility assistance
Annual to public web site
N/A
* Arlington County, VA, benchmarking and disclosure is voluntary
Source: Institute for Market Transformation (http://www.imt.org) New York City The New York City Council on Dec. 9, 2009 passed bill no. 476-A requiring the energy rating and disclosure of public buildings and nonresidential and residential multifamily buildings [4]. The bill was approved along with three other bills related to building energy efficiency, requiring periodic building energy audits and retrocommissioning, lighting upgrades, sub metering of large tenant spaces and the establishment of a city building energy code. Known collectively as the Greener, Greater Buildings Plan, the four bills were supported by New York City Mayor Michael Bloomberg as a key piece of his PlaNYC initiative to reduce the city’s greenhouse gas emissions by 30 percent by the year 2030. Mayor Bloomberg signed the bills into law on Dec. 28, 2009. Nonresidential and multifamily buildings greater than 50,000 square feet in size must benchmark their energy performance annually using the ENERGY STAR Portfolio Manager tool of the U.S. Environmental Protection Agency (EPA). The initial deadline to benchmark is May 1, 2011. Benchmarking data will be posted to a public web site administered by New York City beginning Sept. 1, 2012 for nonresidential buildings and beginning Sept. 1, 2013 for multifamily buildings.
407
Buildings greater than 10,000 square feet owned or fully leased by the New York City government must benchmark their energy performance annually using Portfolio Manager beginning May 1, 2010. Benchmarking data will be posted to the web site. Buildings subject to the benchmarking law are also required to conduct building energy audits and retrocommissioning once every 10 years [4]. Additionally, following the energy audit, city-owned buildings must implement capital improvements with a payback period of seven years or less. Denmark and Portugal have mandated a similar retrofit scheme for its public buildings based on the results of Energy Performance Certificates [6] District of Columbia The Clean and Affordable Energy Act of 2008, passed by the Council of the District of Columbia on July 15, 2008, requires the annual energy rating and disclosure of nonresidential buildings [7]. DC Mayor Adrian Fenty signed the Energy Act into law on Aug. 4, 2008. Although the state of California previously mandated rating and disclosure, the DC mandate was the first in the nation to require commercial building energy performance rating at scheduled intervals (rather than at the time of a transaction) and disclosure to the general public (rather than to transaction counterparties only) via a public web site administered by the District of Columbia. The requirement affects nonresidential buildings greater than 50,000 square feet and is being phased-in over several years. Buildings greater than 200,000 square feet must benchmark their energy performance using Portfolio Manager beginning in 2010. The size threshold decreases by 50,000 square feet each year until 2013, when all buildings greater than 50,000 square feet must benchmark annually. The disclosure of benchmarking data will be phased-in similar to the rating implementation schedule beginning in 2012. Buildings owned or operated by the District of Columbia greater than 10,000 square feet in size were required to begin benchmarking their energy performance using Portfolio Manager in late 2009. The benchmarking data will be posted to the web site. Additionally, newly constructed nonresidential buildings greater than 50,000 square feet that file construction permits on or after Jan. 1, 2012 must estimate their energy performance using ENERGY STAR software and benchmark and disclose their energy performance annually after the building delivers. California The state of California passed Assembly Bill 1103 in 2007, requiring for the first time in the United States the rating and disclosure of nonresidential buildings [8]. California Governor Arnold Schwarzenegger signed the bill into law on Oct. 12, 2007. The California bill is modeled after the Energy Performance of Buildings Directive, requiring building energy rating and disclosure to transaction counterparties prior to the completion of a building sale, lease or financing arrangement. It also requires energy providers to aggregate energy data for buildings and upload it directly into Portfolio Manager upon the request of a building owner, addressing energy privacy concerns by tenants and owners of multi-tenant buildings. This tactic is also being employed by the state of Washington. Initial compliance was delayed from Jan. 1, 2010 to July 1, 2010, and compliance may be delayed further while the California Energy Commission determines rulemaking. The most recent draft rules call for a three-year, phased-in approach to implementation determined by building type and size [9]. The City of San Francisco, located in northern California, may introduce legislation that would build on AB 1103 by requiring public disclosure of energy performance data at scheduled intervals and mandatory energy audits. Those procedures were recommended to San Francisco Mayor Gavin Newsom in a report published in December 2009 by the Mayor’s Task Force on Existing Commercial Buildings [10]. Austin, Texas The Austin City Council approved the Energy Conservation Audit and Disclosure Ordinance on Nov. 6, 2008, requiring building energy rating and disclosure for nonresidential facilities and mandatory energy audits for homes and apartment complexes [11]. Notably, some apartment complexes are also required to undergo energy retrofits. Nonresidential buildings greater than 10 years old must rate their energy performance by June 1, 2011 using Portfolio Manager or a free, online tool from Austin Energy, the municipal utility. Buildings less than 10 years old are required to rate their energy performance within 10 years of the completion 408
of construction. Benchmarking data must be disclosed to prospective buyers prior to a sale transaction. For multifamily properties, a mandatory energy audit replaces the energy performance rating requirement. Audits for existing buildings are required by June 1, 2011. The results of the audit must be posted within the building and provided to prospective tenants and buyers. Additionally, "high energy-use" properties consuming more than 150% of the average multifamily energy use per square foot in Austin must make energy retrofits within 18 months to bring the property to within 110% of the average. The retrofit requirement is the first of its kind for any privately owned, nonresidential property in the United States. Washington The state of Washington passed building energy rating and disclosure legislation in 2009 based on the California mandate. It requires nonresidential buildings to rate their energy performance using Portfolio Manager and disclose benchmarking data to prospective buyers, lessees and lenders prior to the closing of a transaction [12]. The legislation, SB 5854, also requires major improvements to building energy codes and recommendations to the state legislature to rate the energy performance of homes. Washington Governor Chris Gregoire signed the bill into law on May 8, 2009. Nonresidential buildings greater than 50,000 square feet must rate and disclose using Portfolio Manager beginning Jan. 1, 2011, while buildings greater than 10,000 square feet must rate and disclose beginning Jan. 1, 2012. Energy providers were required beginning Jan. 1, 2010 to aggregate energy data for buildings and upload it directly into Portfolio Manager upon the request of a building owner. Public buildings are subject to more comprehensive energy requirements, including new performance standards and mandatory retrofits. The energy performance of public buildings must be rated by July 1, 2010 and reported to a state agency, which will make the benchmarking data public. A preliminary energy audit is required for buildings with poor energy performance (a Portfolio Manager score of less than 50). If cost-effective energy savings are identified by the audit, an investment-grade energy audit is required by July 1, 2013 and cost-effective efficiency measures must be implemented by 2016. Washington has also begun using building energy ratings to set minimum efficiency requirements for state leases in privately owned buildings. Starting Jan. 1, 2010, state agencies may not sign a new lease or renew space in a private building with an ENERGY STAR rating less than 75. Exceptions are allowed when a building owner agrees to undertake an energy audit and implement cost-effective upgrades within the first few years of a state lease. Seattle, WA Less than a year after the state of Washington enacted its rating and disclosure legislation, Seattle, the state’s largest city, passed a city ordinance that expands significantly upon the state law [13]. Seattle City Council Bill 116731, passed on Jan. 25, 2010, augments the state mandate in three ways: • Benchmarking data for nonresidential buildings must be reported annually to the city; • Multifamily buildings are subject to the new reporting requirements; and • Benchmarking data must be disclosed to current tenants in a benchmarked building upon tenant request Nonresidential buildings will annually report energy performance data to the city beginning April 1, 2011 for buildings 50,000 square feet and greater, and beginning April 1, 2012 for buildings 10,000 square feet and greater. Multifamily properties with five units or more will report energy performance data to the city annually beginning April 1, 2012. Multifamily buildings are not covered in the state legislation. Although the city will begin collecting energy performance data, it does not plan to post the data publicly. Arlington County, VA Arlington County, Virginia, a suburb of the District of Columbia began voluntarily posting energy data for county facilities to a public web site in 2009, providing an example for other jurisdictions. For each building, the web site reports annualized energy consumption, site and source energy intensity, greenhouse gas emissions, and Portfolio Manager benchmarking data and plans for energy efficiency improvements, where available [14]. Arlington County does not require privately owned buildings to measure and disclose their energy performance. 409
Evidence of Performance Rating and Disclosure as a Market Force in the United States One of the key reasons for enacting for rating and disclosure mandates is to convey building energy consumption data to real estate consumers, such as tenants, investors and lenders, who may save money by buying, leasing or financing properties with lower energy costs. With more data about building energy consumption available, building consumers can begin to factor energy efficiency and energy costs more fully into their purchasing decisions. If consumers show deference to energyefficient properties, the owners of less efficient buildings will be forced to make building energy efficiency improvements to remain viable in the market. In a best-case scenario, this would cause a significant trend toward energy efficiency in the building sector. Evidence that rating and disclosure mandates will have this effect on real estate markets is limited because most of these policies are new. In many places in Europe and the United States they are enacted but not yet in effect. Yet, evidence is beginning to emerge that suggests this shift is already underway in the United States, where the ENERGY STAR program for commercial and industrial buildings has achieved significant market share on a voluntary basis. As of fall 2009, more than 97,000 buildings totaling nearly 14 billion square feet of floor space had been benchmarked cumulatively over about 10 years on a voluntary basis [15]. Additionally, nearly 1,850 buildings earned the ENERGY STAR label for 2009, the program’s recognition for the nation’s most energy-efficient buildings based upon ENERGY STAR ratings. Using the ENERGY STAR label as a proxy for energy efficiency, several studies compared the occupancy rates, rental prices and sale prices for ENERGY STAR-labeled buildings to comparable “peer” buildings without the ENERGY STAR label. After controlling for variables, the studies universally found rental and sale price premiums for ENERGY STAR-labeled properties, indicating tenants and investors favored those buildings and were willing to pay more to buy or these those buildings. The studies also found higher occupancy rates in ENERGY STAR-labeled buildings, suggesting those properties were more competitive in the market than non ENERGY STAR-labeled properties (See Figure 2). All current U.S. policies mandating commercial building energy rating and disclosure are leveraging the ENERGY STAR program. Figure 2: Market Premiums of Energy-Efficient U.S. Commercial Property
35.00% 30.00% 25.00% 20.00% 15.00% 10.00% 5.00% 0.00%
Rental Premium Sale Price Premium Occupancy Premium
Source: Studies on Market Premiums [16] [17] [18] [19] [20] [21] 410
Energy Performance of Buildings Directive Snapshot The European Union’s Energy Performance of Buildings Directive (2002/91/EC) was approved by the European Parliament in 2002 and enacted in 2003. Article 7 of the EPBD requires Member States of the European Union to develop building energy performance measurement protocols and establish building energy certification schemes for residential and commercial buildings [22]. Specifically, building owners must make energy performance certificates available to prospective buyers and tenants during a sale or lease transaction, or at the time of building construction. Additionally, large buildings occupied by public authorities or institutions providing public services to a large number of people must display an energy certificate in a prominent location within the building. The certificates include building energy performance information and benchmarks as determined by each Member State and recommendations for energy efficiency improvement. The certificates are carried out by qualified energy assessors. Recent, pending revisions to the EPBD would lower the size threshold for buildings requiring the display of energy certificates and would require the numeric energy performance indicator of the energy performance certificate be stated in sale and rental advertisements for buildings [23].
Strategies for Broad European Adoption Quite a few U.S. rating and disclosure policy mechanisms overlap with the requirements of the EPBD. Indeed, quite a few of these policy provisions can be traced back to Europe. However, other U.S. strategies are not covered by the EPBD and are being implemented in only a few EU Member States, or none at all. Many of these policy provisions have the potential for greater adoption in Member States. They include: • • • • • •
Requiring building performance rating and disclosure at scheduled intervals Posting building performance information on a public web site Reporting building performance information to government Disclosure of building performance information to current tenants and prospective lenders Requiring improvements to buildings following performance rating Setting minimum rating standards for government leases
Requiring building performance rating at scheduled intervals Building performance rating at scheduled intervals has emerged as the most popular alternative to point-of-transaction rating and disclosure in the United States. The strategy was pioneered in the District of Columbia and is also being used in New York City and Seattle. All three jurisdictions require annual rating and disclosure, however governments can define the scheduled interval however is most appropriate. In Europe, due to higher costs associated with asset rating, annual intervals may not be practicable. There are a few Member States with scheduled rating requirements, including Denmark, which requires ratings every five years. Rating and disclosing at scheduled intervals has benefits over the point-of-transaction approach: •
It captures more of the market: Rating and disclosure is triggered under the EPBD by a real estate transaction or construction and thus only affects existing buildings immediately preceding a lease or sale. Yet many buildings may sustain prolonged periods without a pending transaction, essentially exempting them from rating and disclosure. The scheduled approach affects buildings regardless of transaction activity and gives building owners a predictable timetable. 411
•
Energy ratings are more comparable: If the time frame for scheduled disclosure is set so the period reflected in the ratings is the same for all buildings, governments can establish baselines for its building stock over a given period. This can be useful in setting future policy goals.
Reporting building performance information to government Quite a few EU Member States are requiring building owners to report building performance information to government, however the requirement is not part of the EPBD. The District of Columbia, New York City and Seattle require reporting to government in conjunction with rating, while Austin requires the reporting of information to a municipal utility. Collecting data on building performance can help governments: • • • • •
Establish an energy efficiency baseline for local building stocks Track progress and identify trends in energy efficiency over a number of years Establish aggregate building performance goals Set standards for incentives and programs related to building energy efficiency Construct future building policy based on performance data
If building performance data is only reported to counterparties in private real estate transactions, governments may lose the ability to do many or all of the items listed above. The Concerted Action EPBD, in its Executive Summary Report on the Interim Conclusions of the CA EPBD (2007 – 2010), recommended that “every MS (or region) should collect EPC data in a central register” for many of the reasons stated above. Posting building performance information to a public web site Rather than disclose building performance on a physical “label”, as is required for some types of buildings under the EPBD, U.S. policies have sought disclosure beyond the point-of-transaction approach via public web sites. The District of Columbia and New York City will both administer public web sites containing building performance data, although neither web site is operational yet. Arlington County, VA, is currently posting performance data for government owned buildings to a public web site. Public web sites may have advantages over physical building energy labels, however more research must be conducted. It is likely that the public would have greater access to information posted on a web site than within a building, bringing more positive recognition to very efficient buildings and more of a “shaming” effect on very inefficient buildings. Specifically, investors and other types of stakeholders in buildings or building ownership groups would also presumably have greater access to building performance information, which may help exert pressure on the owners and operators of inefficient buildings. Denmark and Lithuania are requiring the posting of building performance information to public web sites. Disclosure of building performance information to current tenants and prospective lenders Disclosing building performance information to prospective lenders and tenants already within buildings are logical extensions of the EPBD point-of-transaction disclosure requirements at the time of sale and lease. California, Washington and Seattle require disclosure to prospective lenders. The goal is to allow lenders to understand and more accurately value energy efficiency, which could lead to more favorable financing terms for efficient properties. The full range of issues associated with energy efficiency finance and appraisal is beyond the scope of this paper. The city of Seattle also requires disclosure to current tenants within buildings that must be benchmarked, rather than prospective tenants only. Upon receiving a full-building energy-efficiency rating, tenants may choose to evaluate their operational habits related to energy consumption in its 412
leased space, or pressure the building owner into improving the building’s energy performance (in the case of a low rating). Requiring improvements to buildings following performance rating Mandatory energy performance improvement is gaining traction as a policy mechanism in EU Member States and U.S. states and jurisdictions. In the EU, Denmark and Portugal require some form of mandatory improvement to public buildings per recommendations on Energy Performance Certificates. In the United States, New York City and Washington are requiring mandatory improvement of low-performing public buildings following a building energy audit. The mandatory improvement policy in Austin is interesting, although more research is needed to determine its effectiveness. It is the only such mandatory improvement policy in the nation that affects privately owned buildings (multifamily buildings, in this case.) Setting minimum rating standards for government leases Setting minimum rating standards for government leases can be an effective market tool to encourage more efficiency and better ratings in private buildings. The state of Washington is requiring a minimum ENERGY STAR Portfolio Manager score of 75 in buildings for state agencies to sign leases. The provision is based on a new requirement on federal agencies, enacted in the Energy Independence and Security Act of 2007, to only sign leases in buildings with ENERGY STAR Portfolio Manager scores of 75 or higher [24]. In Australia, this strategy has worked well to influence the private market. The state governments of Victoria and New South Wales, which require minimum energy ratings for leased and purchased real estate, have established de facto minimums among some building types based entirely on efficiency requirements for government space [25].
Conclusions In the Energy Performance of Buildings Directive, European policymakers have created and enacted far-reaching requirements on commercial buildings to measure and disclose their energy performance. Although no equivalent policy exists in the United States, states and local jurisdictions are becoming creative in crafting rating and disclosure requirements. In some cases, those requirements may benefit government and real estate stakeholders in ways which the EPBD does not. Both Europe and the United States stand to benefit by sharing best practices and new ideas on rating and disclosure mandates. As shown by real estate data on energy-efficient property in the United States, rating and disclosing building performance does impact the leasing and purchasing decisions of tenants and real estate investors. It is likely this impact will grow as more buildings are rated and more ratings are disclosed per legislative requirements now being enacted, which may result in larger competitive advantages for energy-efficient properties and more market pressure on less efficient properties to improve their energy performance. The task of policymakers in Europe, the United States and elsewhere is to determine the most effective methods of measuring building performance and disclosing that information to the marketplace.
References [1] Houser, T. The Economics of Energy Efficiency in Buildings. Peterson Institute for International Economics, Number PB09-17. August 2009. Available at http://www.iie.com/publications/pb/pb0917.pdf [2] PlaNYC Progress Report 2009. Spring 2009. Available at http://www.nyc.gov/html/planyc2030/downloads/pdf/planyc_progress_report_2009.pdf [3] Dunsky P., Lindberg J., Piyalé-Sheard E. and Faesy R. Valuing Building Energy Efficiency Through 413
Disclosure and Upgrade Policies: A Roadmap for the Northeast U.S. November 2009, p. 4. Available at http://neep.org/uploads/policy/NEEP_BER_Report_12.14.09.pdf [4] New York City Council. Council Int. No. 476-A regarding the energy performance rating and disclosure of buildings, 12/14/2009. Available at http://www.imt.org/files/FileUpload/files/Benchmark/Int%20476.pdf [5] New York City Council. Council Int. No. 967-A regarding energy audits and retrocommissioning of buildings, 12/14/2009. Available at http://www.imt.org/files/FileUpload/files/Benchmark/Int%20967.pdf [6] Ries C., Jenkins J. and Wise O. Improving the Energy Performance of Buildings: Learning From the European Union and Australia, 2009, p. 9. ISBN 978-0-8330-4787-8. Available at http://www.rand.org/pubs/technical_reports/2009/RAND_TR728.pdf [7] Council of the District of Columbia. Clean and Affordable Energy Act of 2008 regarding the energy performance rating and disclosure of buildings. Available at http://bcapenergy. org/files/DC_Clean_Affordable_Energy_Act_2008.pdf [8] California State Assembly. Assembly Bill No. 1103 regarding the energy performance rating and disclosure of buildings. Available at http://info.sen.ca.gov/pub/07-08/bill/asm/ab_11011150/ab_1103_bill_20071012_chaptered.pdf [9] California Energy Commission. Draft Regulations: Implementing Assembly Bill 1103, CEC-4002009-011-SD, August 2009. Available at http://www.energy.ca.gov/2009publications/CEC-400-2009011/CEC-400-2009-011-SD.PDF [10] Mayor’s Task Force on Existing Commercial Buildings. Final Report and Recommendations for the City and County of San Francisco, December 2009. Available at http://www.imt.org/files/FileUpload/files/Benchmark/sf_existing_commercial_buildings_task_force_rep ort.pdf [11] City Council of Austin. ORDINANCE NO. 20081106-047 regarding building energy efficiency requirements. Available http://www.austinenergy.com/About%20Us/Environmental%20Initiatives/ordinance/ordinance.pdf
at
[12] Washington State Senate. Senate Bill No. 5854 regarding building energy efficiency http://apps.leg.wa.gov/documents/billdocs/2009requirements. Available at 10/Pdf/Bills/Session%20Law%202009/5854-S2.SL.pdf [13] Seattle City Council. Council Bill Number116731 regarding building energy rating and disclosure. Available at http://clerk.ci.seattle.wa.us/~scripts/nphbrs.exe?s1=&s3=116731&s4=&s2=&s5=&Sect4=AND&l=20& Sect2=THESON&Sect3=PLURON&Sect5=CBORY&Sect6=HITOFF&d=ORDF&p=1&u=%2F%7Epubl ic%2Fcbory.htm&r=1&f=G [14] http://www.arlingtonva.us/portals/topics/aire/BuildingEnergy.aspx [15] U.S. Environmental Protection Agency ENERGY STAR Division. ENERGY STAR Snapshot: Measuring Progress in the Commercial and Industrial Sectors, Fall 2009. pp. 1-2. Available at http://www.imt.org/files/FileUpload/files/Benchmark/ENERGY_STAR_Snapshot_Fall_2009.pdf [16] Miller N., Spivey J. and Florance A. Does Green Pay Off? Journal of Sustainable Real Estate, 7/8/2008. Available at http://www.costar.com/josre/pdfs/CoStar-JOSRE-Green-Study.pdf [17] Miller N. and Pogue D. Do Green Buildings Make Dollars and Sense? USD-BMC Working Paper 09-11, 11/10/2009. Available at http://www.imt.org/files/FileUpload/files/Benchmark/DoGreenBuildingsMakeDollarsSense2.pdf 414
[18] Pivo G. and Fisher J.D. Investment Returns from Responsible Property Investments: Energy Efficient, Transit-oriented and Urban Regeneration Office Properties in the US from 1998-2008, 3/3/2009. Available at http://www.u.arizona.edu/~gpivo/Pivo_Fisher_Investment%20Returns%20from%20RPI%203_3_09.p df [19] Eichholtz P., Kok N. and Quigley J.M. Doing Well by Doing Good? Green Office Buildings. Working Paper No. W08-001, August 2009. Available at http://urbanpolicy.berkeley.edu/pdf/EKQ_green_buildings_JMQ_081709_long.pdf [20] Fuerst F. and McAllister P. New Evidence on the Green Building Rent and Price Premium. Proc. Of the Annual Meeting of the American Real Estate Society, Monterey, CA, 4/3/2009. Available at http://www.henley.reading.ac.uk/rep/fulltxt/0709.pdf [21]Wiley J., Benefield J., and Johnson K. Green Design and the Market for Commercial Office Space. Journal of Real Estate Finance and Economics, forthcoming. [22] European Council. Directive 2002/91/EC Of the European Parliament and of the Council of 16 December 2002 on the energy performance of buildings. Official Journal L 1/65, 4/1/2003. Available at http://www.euroace.org/comdocs/CD_161202.htm.pdf [23] European Council. Proposal for a Directive of the European Parliament and of the Council on the energy performance of buildings. 2008/0223 (COD), 11/18/2009. pp. 25-28. Available at http://www.beenonline.net/fileadmin/medias/downloads/beenetwork/news/2009nov/st16082.en09.pdf [24] U.S. House of Representatives. Energy Independence and Security Act of 2007. U.S. Government Printing Office. pp. 124-125. Available at http://frwebgate.access.gpo.gov/cgibin/ getdoc.cgi?dbname=110_cong_bills&docid=f:h6enr.txt.pdf [25] Ries C., Jenkins J. and Wise O. Improving the Energy Performance of Buildings: Learning From the European Union and Australia, 2009, p. 34-35. ISBN 978-0-8330-4787-8. Available at http://www.rand.org/pubs/technical_reports/2009/RAND_TR728.pdf
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Measurement and simulation of a commercial building in Norway Matthias Haase, Catherine Grini, and Tore Wigenstad NTNU, Department of Architectural Design, History and Technology SINTEF Building and Infrastructure, Buildings department, energy and environment group
Abstract A commercial building in Trondheim was energetically measured over a 3 years period. Trondheim municipality is renting the entire building and responsible for further use. The building has 6 storeys, 5 above ground level, a basement floor (+ some area on the 6th floor as management and ventilation plant rooms) and was built in 2001. The building consists of communal offices and shops on the 1st and various offices on 2nd to 5th floor. The programme shows a business area in the ground floor and mainly of offices in the other floors while parking is located in parts of the basement. The building form consists of 2 almost rectangular parts linked together. Gross floor area is approx. 8425m² (heated floor area: 7010m2). The building is compact, with 200mm insulation and windows with an U-value for the entire window of 1.4 W / m². K. External roller shutters, manually controlled, were used as solar controls. The ventilation system consists of balanced ventilation with heat exchanger, manually controlled by technical staff. District heating and cooling was purchased together with electricity from the local energy supplier. 2 Total energy supply was measured to be 191 kWh/(m a). The building energy consumption was simulated and a comparison with measured data shows good agreement. The difficulties with modeling the building are described and the recommendations derived from that are discussed. Then it was possible to analyze the energy use in the building in more detail and different measures for reducing energy use could be determined. A cost benefit analysis showed a list of cost effective energy saving measures. Here, it became clear that e.g. the optimized use of the ventilation system is much more cost effective than reducing the U-value of the windows by shifting to new windows.
Introduction Energy use in buildings varies over different building types. Figure 1 shows delivered energy in different building types in Norway and the net energy frame according to technical requirements [1]. It can be seen that in office buildings as well as commercial buildings further energy savings are needed.
Figure 1: Measured and temperature corrected delivered energy and net energy demand according to TEK07 in different building types enova: averaged measured and temperature corrected delivered energy TEK07: netto energy demand 450 400 350 kWh/m2/yr
300 250 200 150 100 50
sp
or ta ho re na te l co /s m t cu a m d ltu iu er m ra ci al lb b ui u lig ld ild in ht in g in g /m du us st ry eu /r m ep ai rs ho p
ho ol hi gh sc ho ol ho sp nu ita rs l in g ho m e
sc
un
iv er si ty /
ar de n bu ild in g of f ic e
de rg
k in
ap
ar tm
en
tb
ui
ld
in
g
0
Measured energy use A commercial building in Trondheim was energetically measured over a 3 years period. Trondheim municipality is renting the entire building and responsible for further use. The building has 6 storeys, 5 above ground level, a basement floor (+ some area on the 6th floor as management and ventilation plant rooms) and was built in 2001. The building consists of communal offices and shops on the 1st and various offices on 2 to 5 floor. The programme shows a business area in the ground floor and mainly of offices in the other floors while parking is located in parts of the basement. The building form consists of 2 almost rectangular parts linked together. Gross floor area is approx. 8425m² (heated floor area: 7010m2). The building is compact, with 200mm insulation and windows with an U-value for the entire window of 1.4 W/(m²K). External roller shutters, manually controlled, were used as solar controls. The ventilation system consists of balanced ventilation with heat exchanger, manually controlled after outdoor temperature. District heating and cooling was purchased together with electricity from the local energy supplier.
417
Figure 2: View and plan of the building (picture from [2])
Measured delivered energy for this office building was 191 kWh/(m2a) in the period 2006-2008. After heating degree days correction (for 2008), the delivered energy is 218 kWh/(m²·a) for normal weather (average measured in period 1961-1990). Energy use in commercial buildings in Norway When looking at energy use in buildings the following three items are important as illustrated in Figure 3: • Net energy demand (according to TEK) • Calculated delivered energy (efficiency factors from NS3031) • Real delivered energy Figure 3: From net energy demand to CO2 emissions of delivered energy according to [3]
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Net energy demand National building regulations in Norway have been revised and tightened several times since the first numerical requirements were introduced in 1949. The purpose of the recurrent upgrades has basically been to reduce the heating demand, thus reducing the overall energy use in the building. As a consequence of the Norwegian partnership in the EEC, Norway is obliged to implement the EU Energy Performance of Buildings Directive (EPBD) in the national laws and regulations [1, 4]. Thus, the new building codes and guidelines are also revised. While the former regulations concerned building’s heating energy demand, the new regulations incorporate all energy needed to operate the building. The calculation method has been revised in Norway in 2007 [3]. In addition, building regulations were revised [1] introducing two ways to fulfill the energy requirements for a building. • Energy measure method (Energitiltak) • Energy frame method (Energirammer) The so-called Energy measure method (Energitiltak) has to set requirements for certain building elements and installations. The requirements are listed in Table 1. For code compliance these requirements have to be fulfilled and documented. Table 1: The new building regulations for commercial and residential buildings [1] Commercial TEK 1997
TEK 2007
Glass and door area a
20 %
20 %
U-value external wall (W/(m2K))
0.22
0.18
U-value roof (W/m2K)
0.15
0.13
U-value floor on ground (W/(m2K))
0.15
0.15
U-value windows / doors b (W/(m2K))
1.6 / 2.0
1.2 /1.2
U-value glazed walls and roofs (W/(m2K))
same as for windows
same as for windows
normalized thermal bridge value (W/m2)
Included in window
0.06
air tightness c (ach)
1.5
1.5
heat recovery (%)
no requirements
70
specific fan power (SFP) (kW/(m3/s))
no requirements
2.0/1.0 e
local cooling
no requirements
shall be avoided f
temperature control
no requirements
night set-back to 19°C
d
a
maximum percentage of the buildings heated floor area as defined in NS3031
b
incl. frames
c
air changes per hour at 50Pa pressure
419
d
annual mean temperature efficiency
e
SFP day/night
f
automatic solar shading devices or other measures should be used to fulfill the thermal comfort requirements without use of local cooling equipment Alternatively, if the net energy demand for the building, calculated according to the methodology established in the new Norwegian Standard NS3031 (2007), is within the energy frame for the building’s category, the regulations are also satisfied [3]. Here, a holistic approach was chosen, accounting for all energy a building needs (see Table 2 for all components). The frame for aggregate net energy demand for different building types is also shown in the last row of Table 2. Since the frame is based on net specific energy demand per year, the efficiencies of the energy systems are not taken into account. This means that for example the coefficient of performance of a highly efficient mechanical cooling system is not rewarded. However, passive measures that reduce the net cooling demand will contribute to satisfy the energy frame. This has led to a renewed interest in utilizing passive measures to decrease the total energy use in all building types. Table 2: Energy frame for different building types (kWh/m2 per heated floor area) office building
retail building
heating
33
45
heating coil
21
34
warm water
5
10
fans and pumps
22
42
lighting
25
56
technical equipment
34
4
cooling
0
0
cooling coil
24
47
sum netto energy demand
164
238
rounded energy frame
165
235
a
heated floor area according to NS3031
However, there are still minimum requirements concerning the U-values and air tightness of the building envelope which help to maintain a good insulation standard. These are listed in Appendix A, Table 3 of TEK07 [1]. TEK07 is now under revision. A strengthening of the requirements is envisioned [5, 6].
Delivered energy In order to account for delivered energy system losses due to regulation, distribution, and production have to be taken into consideration and allow to link between net energy demand and delivered 420
energy. Annual average energy system efficiencies are recommended to use in Table B9 of [3]. Advanced building simulation tools can help to calculate system losses more accurately. The only system efficiency that is required to use in TEK07 is the heat recovery system efficiency which directly reduces net energy demand of ventilation air (due to heating of ventilation air). Table 3: Efficiency factors for different energy supply systems (from Table B9 in [3]) Supply system
1
2
3
4
5
6
7
Supply of heating and hot water
el
oil boiler
gas boiler
district heating
solar thermal
biofuel
PV
efficiency factor
0.98
0.73
0.73
0.84
8.55
0.84
100
It can be seen from Table 3 that a heating system based on electricity has an efficiency of 0.98 while a water based district heating system has an efficiency of 0.84, i.e. the same building with identical net energy demand and two different supply systems shows 14% difference in delivered energy. Table 4 gives the maximum amount of delivered energy for labeling buildings. Table 4: Delivered energy in energy labeling system (from [7]) delivered energy building type
office building commercial building
A
B
C
D
E
F
G
10’000 m2 sales area) the analysed data of one facility showed that the proposed values according to SIA 2024 are attainable. The analysis showed that in order to improve future definitions of standard values, it is important to carefully consider and acknowledge the differences in both sales area and the share of fresh products (with refrigeration demand). The specific consumption of thermal energy ranges from 75 to 800 MJ/m2 and the average value over all 32 retail facilities is 350 MJ/m2. The age, type and size of the building were identified as the main impacting factors that jointly determine the consumption of thermal energy. Also of importance are the ventilation rates and the control of the ventilation, the use of heat recovery, the type of heating (e.g. heat pumps vs. fossil energy heating systems) and the level of required room condition (temperature). Table 21 Comparison of the specific energy consumption derived from the survey with the bench marks acc. to SIA standards
Survey RAVEL (1996) SIA 2024, SIA 380/4 SIA 380/1 (2001) SIA 380/1 (2009) Survey 2008
electricity SEC [MJ/m2]
thermal SEC [MJ/m2] (base: end energy)
SA < 300 m
290
1800
2
SA: 300-2000 m
a)
305-439 b) b) 256-441 350
1480 250-720
2
SA > 2000 m
2
1330
1970
Base for specific energy consumption (SEC) is the sales area (SA). a) not applicable (value is not comparable) b) Value for a facility with a sales area of 80%-50% of the conditioned gross floor area.
Source [6]
Lessons learned The conclusion of the comparative evaluations is that there is a clear distinction between electricity-related and thermal energy services. For thermal applications, which are dominated by space heating in buildings, the taken measures in the past years (e.g. new regulations) show improvements in efficiency. On the other hand for electricity-related services the efficiency gain through renewals is often compensated by a higher equipment and service level. The experience gained from the survey showed that approximately half of the buildings approached experience significant problems with determining the energy consumption for the last three years or one year. The contacted persons and enterprises stated an even larger
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problem with even roughly indicating the history of the energy-relevant refurbishment measures. With these findings it can also be noted that with approximately half of the buildings, the important basic conditions for capital and operational energy efficiency measures, which affect this need, i.e. knowledge of the energy consumption and the influencing factors, are either inadequately or not at all present. Here the Energy Agency for Industry (EnAW) benchmark models or goal/incentive agreements with large consumers, which are planned with the new model regulation in many cantons in the energy law, can be a good means to bring up a discussion on energy consumption or and to put a focus on the continuous operational optimisation thereof. Moreover, the effect is strengthened by it’s coupling to efficiency-oriented electricity tariff systems (like e.g. the efficiency bonus of EWZ, the utility of the city of Zurich). Furthermore, similarly suitable tools should be created, also in co-operation with the energy supply company, for smaller buildings and/or enterprises.
References [1] [2] [3] [4] [5] [6]
[7] [8] [9] [10] [11]
Swiss Federal Office of Energy (SFOE), electricity statistics of Switzerland, 2009 Weber Lukas: Energieverbrauch und energierelevante Entscheidungen in Bürogebäuden. Zürich: Diss. ETH Nr. 14345, 2001 Menti Urs-Peter; „Standby-Verbrauch“ von Dienstleistungsgebäuden – Verbrauchsmessungen an 32 Gebäuden. Zürich: April 1999 Martin Jakob, Andreas Baumgartner, Iwan Plüss et. al.; Grenzkosten bei forcierten Energie-Effizienz-Massnahmen und optimierter Gebäudetechnik bei Wirtschaftsbauten; im Auftrag des BFE, Bern: Nov. 2006 Weber Lukas; Menti Urs-Peter; Keller Ivan; et al.: Energieverbrauch in Bürogebäuden. Zürich: April 1999 Aiulfi D., Maschio I., Dellsperger V., Brunet V., Primas A., Hagel M., Benz-Karlström P, Jakob M., A. Honegger-Ott A., B. Grodofzig Fürst B. Energieverbrauch von Bürogebäuden und Grossverteilern. im Auftrag des Bundesamtes für Energie (BFE), Bern: 2009 Bundesamt für Energie BFE, Zukünftige Entwicklung der Energiebezugsflächen, Perspektive bis 2035 Schweizerischer Ingenieur- und Architektenverein 08/2006, SIA Merkblatt 2024: Standard-Nutzungsbedingungen für die Energie- und Gebäudetechnik, Zürich Schweizerischer Ingenieur- und Architektenverein 2006, SIA 380/4: Elektrische Energie im Hochbau, Zürich Schweizerischer Ingenieur- und Architektenverein 2009, SIA 380/1: Thermische Energie im Hochbau, Zürich Guide pour les magasins d'alimentation, RAVEL, Office fédéral des questions conjoncturelles, 1995, 724.323f.
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Energy Consumption in Non-Domestic Buildings Richard Kilpatrick, Professor Phillip Banfill Heriot-Watt University Keywords: Electrical Demand; non-domestic buildings, energy Abstract The energy consumption associated with non-domestic buildings represents 11% of the UK’s total energy consumption, 11% of Europe and 18% of the USA’s. Annual non-domestic building energy consumption is often presented in the form of average benchmarks, such as 350kWh/m2 for a large air-conditioned building and 200kWh/m2 for a small naturally ventilated office. One problem with benchmark values is that they only highlight total annual energy use, hence giving very little insight into how and where a building is actually consuming energy. Some benchmarks provide a breakdown of energy use by energy category (lights, IT, cooling, heating) however, this data still fails to demonstrate how the energy associated with these categories varies throughout the year. To further understand building energy use, more detailed data and analysis is required. In conjunction with a local council, the electricity demand data for a variety of office, school and public buildings has been made available for analysis. This data consists of half hourly resolution data spanning two years, for 17 types of non-domestic buildings. By performing basic analysis on the data, key trends and patterns in energy use can be identified. These trends can include differences between annual profiles, differences between winter and summer months, and differences in weekday and weekend energy use. Additionally, other variables can be investigated including climate, user behaviour and general building data to determine how they influence a building, hence affect the buildings energy consumption. The paper will describe the creation of a database of half-hourly building energy demand data, along with the collation of corresponding building information (such as floor area and occupancy) and local climate data (from onsite weather stations). A methodology will be proposed to ascertain the degree to which the pattern recognition is possible in non-domestic energy usage, and the variables that should be used to calibrate this data, with the possibility of “standardised” energy profiles as a result. Introduction Non-domestic buildings consume around 11% [1]of the UK’s total energy consumption. This percentage of total consumption can be compared with the EU and the USA, which stand at 11%[1] and 18%[1] respectively. Within the 11%[1] of energy associated with non-domestic buildings, offices can account for around 17% [1] of this proportion. To understand why non-domestic buildings consume a sizable percentage of the UK’s total energy demand, the energy demand of individual buildings have to be understood. Benchmark data, or performance indicators, can be used to provide an insight into average annual building energy consumption. Several sources of building benchmarks can provide breakdowns of annual consumption values into categories, such as lighting and heating. The research discussed in this paper is aimed at determining whether it is possible to create generalised office energy demand profiles, based on empirical data to describe energy consumption pattern throughout the course of a day. Due to the availability of data, this paper will only be investigating electricity use, but gas consumption is also being considered by the project. By analysing the measured data, key trends can be identified and investigated, including factors such as the effect of climate, floor area and number of occupants. Where applicable, the data can then be normalised by these different variables, to investigate the consistency in energy pattern for different building categories. Benchmark Data Annual non-domestic building energy consumption is often presented in the form of average benchmarks. An example of office benchmarks can be found in the Energy Consumption Guide 19, usually referred as ECON19 [2]. ECON19 is a guide aimed at “raising awareness of the potential to improve energy and environmental efficiency of offices”. To achieve this, the guide has calculated average annual performance indicators for four types of office buildings. The offices range from small naturally ventilated offices, to large air conditioned offices. For each building, there are both a ‘typical’ value and a ‘good practice’ value. The typical is based on the average consumption of a wide range of building consumption data. The ‘good practice’ is based on the average consumption of buildings that have adopted energy efficient measures. Examples of these benchmarks are 220kWh/m² for a
557
typical small office and 350kWh/m² for a good practice large air conditioned office. In addition to the annual benchmark figures, the ECON19 also provides breakdown of each benchmark into energy use category. This is useful in determining the percentage of key energy use areas such as heating, lights and IT equipment. Energy performance benchmarks are also available for other types of buildings. Example of school benchmarks can be found in practice guides [3]. For a primary school, the ‘typical’ annual consumption is 191kWh/m² where as the ‘good practice’ value is 135kWh/m². For a secondary school without a pool, the ‘typical’ benchmark is 196kWh/m² and for a secondary school with a pool, the benchmark is 223kWh/m². The guide also provides the breakdown of the benchmarks into either electricity or fossil fuels, and provides a generalised breakdown of energy use in schools represented by a pie-chart. One issue with these forms of benchmark figures is that they only give estimated annual energy consumption for a certain very generalised category of building. This gives little insight into the daily, weekly or even seasonal variations. There are several factors that can influence the energy consumption of a building. Clearly the surrounding climate will have an impact on an office’s energy consumption, with buildings in a tropical environment having different energy requirements than a building in a cooler climate. Evidence of this climate influence can be seen when investigating different benchmarks. In Hong Kong, the electricity benchmark for an office is 270kWh/m² [4], whereas an office in a Nordic country can have an electricity benchmark of 144kWh/m² [5]. This can also be seen in schools, with a Greek school consuming 95kWh/m² [6] and 65kWh/m² [7] for an Irish school. Additionally, how the building is used and the number of occupants can also influence building energy consumption, though it is very difficult to understand what is happening in that building without breaking down that energy use by time of day. The data collected by this project is done so with this in mind, aiming to achieve a suitable level of temporal precision. Data collection The research discussed in this paper uses half hourly electrical demand data provided by the City of Edinburgh Council. The data spans more than 12 months and includes 17 different council buildings. The buildings range from office buildings, to theatres and to transport depots. The data has been provided through Edinburgh Council’s energy supplier. As well as being accurate, it removes the need to purchase expensive voltage monitoring equipment. If voltage monitors were used to collect the same volume of information provided by the Council, this would have required several monitors in several buildings. In addition, data from previous years was also available, increasing the data base without increasing the data gathering time. Although a range of different types of buildings have been provided, and will form part of the wider research project, this study will focus on offices and schools. Also, as discussed in the “Future Work” section, this database of non-domestic building energy consumption patterns will be added to (as data becomes available), such as the corresponding conclusions become more statistically significant to specific areas of the building stock. Results Offices From the electrical demand data provided by The City of Edinburgh Council, only four buildings were classified as offices. These buildings range in both size and annual energy consumption. Table 1 demonstrates several details of each of the four selected offices. Table 1 – General Building Details Office 1 Office 2 Office 3 Office 4 Floor area (m²) 12,220 20,717 3,699 2,250 Total Electrical 2,907,428 2,612,895 434,959 329,392 Use(kWh) Normalised Electrical 237.92 126.12 117.58 146.39 Use(kW/m²) No of Floors 7 5 1 1 Year of 1960 2007 1980 1994 Construction Heating/Cooling Mechanical Mechanical Mechanical Mechanical Ventilation, gas Ventilation, Cool Ventilation, gas Ventilation, gas Beam, gas Elevators 3 5 0 0
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Figure
1
-
Average
daily
demand
profiles
Initial analysis of the electrical demand data involved creating average daily profiles to determine the shape of each buildings energy use. The average profiles represent an average weekday profile, as opposed to incorporating both weekdays and weekend days. Figure 1 demonstrates the power demand profile for each studied office, in kW, throughout the day. This figure highlights that the buildings have very similar patterns of power use, with similar gradients in energy use at similar times. The power demand profile of each office starts rising from the base load at a certain point of the day, say the buildings opening hours, then rises to its peak value. The profile then slowly slopes back towards the base, and reaches the base load value after occupants leave the building. If Office 2 is selected and studied in further detail, an estimate into building activity can be obtained. The building has an average base load of around 200kW and begins to increase at 0430hrs. This baseload will be a mix of heating pumps and IT servers. This initial ramp could be the result of electrical heating pumps being turned on. The second rise occurs between 0530hrs and 0900hrs, where it begins to plateau. This second rise is most likely the result of lighting and IT equipment being turned on as the occupants enter the building. Additionally, increased usage of networked computers would cause increased server usage, hence result in additional cooling demand. The peak demand of 560kW occurs at 1200hrs and could be associated with the office’s cafeteria preparing for lunchtime. The first negative gradient occurs from 1200hrs until 1600hrs with lighting and IT equipment being slowly turned off. A further change in gradient occurs from 1600hrs until 1730hrs and is most likely the result of occupants leaving the office, hence lights and computers being turned off. The last part of this gradient feature occurs from 1730 until 2100 where it approaches the base load value. This slope is likely to be the result of late evening working hours/operations.
559
Figure
2
-
Normalised
Office
Energy
Consumption
Profiles
If the average daily profiles, in kW, are reviewed then it could be concluded that buildings 1 and 2 have very similar energy usage both in terms of shape and consumption. Equally, this statement can be true of buildings 3 and 4. The consumption data has to be normalised to create a fair comparison between the buildings. Figure 2 demonstrates the same office average profiles shown in Figure 1, but the data has been normalised using the floor area given in Table 1 to give kW/m². It can be seen in Figure 1 that the profiles have retained their shape, but the base load and peak values are different. The original conclusion that offices 1 and 2 are similar, as are offices 3 and 4, is now no longer true. It should be observed that the last three offices have almost the same base load. From the results shown in Figure 2, it could be argues that building 2, a 5 storey office, has the same normalised consumption as a single story office. Results from the basic analysis can be found in Table 2. While normalising by floor area us a common process when analysing building energy comsumption data, this project aims to identify other variables that could be used for additional normalisation. For example, further investigation will be needed to determine why office 1 consumes almost double the standby power than the other three offices. Table 2 – Basic office analysis results
Office 1 Office 2 Office 3 Office 4
Base Load(kW/m²) 0.01742 0.0078 0.00786 0.00656
Peak Load(kW/m²) 0.0472 0.0272 0.028 0.0378
Daily Consumption(kWh/m²) 0.735 0.405 0.763 0.48
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Figure 3 – Seasonal Weekly Demand Profiles for office 3
The changing seasons can have a noticeable impact on a building’s energy consumption. This research project defines Spring as March to May, Summer as June to August, Autumn as September to November and Winter as December to February. This is apparent when investigating the seasonal variations of an office’s energy consumption. Figure 3 demonstrates average weekly profiles for each of the seasons for office 3. Each of the seasonal profiles are very similar in terms of rise/fall times and peak value, relative to the base load. The main difference between the profiles is the baseload. The average summer baseload for office 3 is 16kW, where as the average winter baseload is 39.2kW. Spring and autumn have closely matched baseloads, with spring averaging 27.6kW and autumn averaging 26.8kW. If the average weekly enery consumptions are investigated, a summer week consumes over 6,000kWh and winter consumes over 10,500kWh. The differences between winter and summer, both energy consumption and electricity demand profiles, could be the result of several factors. The extra use of artificial lighting, to adjust for the reduced natural lighting hours of winter, could affect over all consumption. However, switching on extra lighting or switching existing lighting on at earlier times, would result in different peak power characteristics, or change the profile shape. The differences between the profiles are mainly the baseloads, not profile shape. This could suggest that lights are being left on constantly, perhaps in reception areas, or corridors. Another possible reason for the increase in baseload could be due to the electric pumps used in the heating system being left on throughout the day and night. Spring and autumn’s profiles lie halfway between summer and winter profiles, which is consistent with this pattern. This trend in seasonal energy use is also apparent in the remaining offices.
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Figure 4 – Summer Average Demand Profiles
Figure 4 displays the normalised (by floor area) weekly summer profiles for each of the four selected offices. These average summer profiles can provide several useful insights into energy use. The first is that a general “Monday to Sunday” pattern of electricity consumption can be seen. Using a daily average profile, constructed from averaging all 365 days, will give little information about how energy is used from day to day. For each office, there appears to be little activity during Saturday and Sunday, apart from office 2, which shows a small amount of activity on both days. However, the peak weekend electricity use is considerably smaller with an average demand of 0.010kW/m² compared to 0.034kW/m². It can be seen in Figure 4 that offices 3 and 4 appear to operate similar working hours as indicated by their profile shapes overlapping each other. Offices 1 and 2 do not appear to operate on a typical “9-5”workday. This can be explained by investigating what types of offices these studied buildings are. Office 3 and 4 are small single purpose offices that take care of building services (office 3) and depot management (office 4). Both offices have identical operating hours; from 0830hrs-1700hrs. Office 1 and 2, on the other hand, contain several departments that serve several different purposes. Office 2 includes a customer zone, that operates on different opening and closing hours that the rest of the building. Schools The school data was supplied in the same format as the office data. The five selected schools range in size and age of construction. Table 3 provides several details on each of the selected school. On initial inspection, the schools could be grouped into three possible groups; new build, old build and retrofitted old build. Schools 1 and 5 have similar characteristics, as do schools 2 and 3. Table 3 – General School Building details School 1 School 2 Construction date 1976 2007 Floor Area(m²) 12,366 10,284 Number of Pupils 912 716 Annual Electricity 903,706 712,315 Consumption (kWh) ü û Swimming Pool Evening Classes 1800-2200 1800-2200 Weekdays Weekdays 0800-1200 0800-1200 Saturdays Saturdays Heating Gas Boilers Gas Boilers
School 3 2008 12,435 852 1,104,376
School 4* 1995 8,835 656 672,038
School 5 1979 10,156 776 492,587
ü 1800-2200 Weekdays 0800-1200 Saturdays Gas Boilers
û 1800-2200 Weekdays 0800-1200 Saturdays Gas Boilers
û 1800-2200 Weekdays 0800-1200 Saturdays Gas Boilers
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Cooling/Ventilation
Mix of Mix of Mix of Mechanical Mechanical Mechanical and Air Con and Air Con and Air Con *Built in 1965, retrofitted and extended in 2008
Mix of Mechanical and Air Con
Mechanical
Figure 5 – Average Daily School Profiles
A similar analysis as used with the office data was applied to the school data. An average profile to represent an average workday, or school day, was calculated. Figure 5 represents the five average daily school electric demand profiles. The average daily profiles were used to determine whether the original groupings stated previously were accurate. The profiles appear to have comparable working or opening hours, highlighted by the main profile shapes occurring at the same time. If one school is analysed, a clearer idea of the school’s demand or activity can be estimated. School 5 remains at baseload, 30kW, until 0600hrs where it slopes up to 106kW at 1000hrs. This slope is most likely due to heating systems (electrical pumps) lighting, I.T equipment and possibly catering staff preparing for lunch Several fluctuations in electrical demand occur from 1000hrs to 1300hrs. These slight changes in demand could be due to lights being turned off as pupils leave for lunch, and the cafeteria serving lunch. From 1300hrs until 2000hrs there is a gradual decrease in energy use until the demand reaches the original baseload. This decrease could be associated with the switching off of lighting, catering facilities and computers and electronic white boards. The gradients of the slopes are dependant of the energy management of the school and the extent of the schools IT equipment.
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Figure 6 – Normalised Average Daily Demand Profiles
Figure 6 represents the same average daily profiles as Figure 5, but with the values normalised by floor area. If electrical demand, in kW, is plotted as demonstrated in Figure 5, the profiles have a fairly wide spread. This spread can be made more apparent by focusing on the baseload values. The profile baseloads have values ranging from 40kW to 80kW. This range in values makes it difficult to create an accurate generalised profile, without introducing large errors. If however, the normalised profiles are investigated, Figure 5, it can be seen that the removal of floor area has grouped the profiles together. Schools 1 to 4 have baseload values ranging from 0.0054-0.0058kW/m², whereas school 5 has a baseload value of 0.003kW/m². If school 5 is removed from the analysis, the remaining schools appear to have a fairly generic demand shape. It should be noted that this general demand profile shape is only representative of the studied schools. The main difference between the grouped profiles appears to be the peak demand value and operating hours. The peak demand can depend on several factors, including whether the building uses large flood lamps in open areas, how big the catering facility is, and whether the school has a (electrically) heated swimming pool. In relation to this, schools 1 and 3 have heated swimming pools, and through further investigation, it was determined that both pools are gas heated. The difference in operating hours is made apparent when schools 1,2 and 3 are compared. Schools 1 and 3 appear to have the same operating hours, with a 0630hrs start in demand and the demand reaching baseload value by 2200hrs. The demand in energy after the standard schools hours of 0800 to 1600 indicates that the schools are used during the evening. If Table 3 is referred to, it can be seen that all five schools are used for evening classes. Further investigation determined that the out of school hours usage is mainly due to the sports facilities being used. School 2 also appears to have a small amount of activity from 1800hrs to 2200hrs. An interesting observation is that the older school, school 5, has a smaller demand than the newer built schools. An onsite visit or equipment inventory has not yet been carried out on this school, so any possible explanations for the lower power demand are purely speculative. Referring to Table 1, it can be seen that school 5 uses primarily mechanical ventilation, with no air conditioning. The lack of air conditioning units can have a dramatic saving on power demand. Other explanations could be the lack of introduction of smart white boards and projectors, increased use of natural light and smaller catering facilities.
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Figure 7- Average Normalised School Spring Weeks
An average seasonal week for each school was calculated, using the same method applied to the office data. Figure 7 represents an average spring week for each of the schools. From is, it can be seen that there is a difference in peak power demand between each of the schools. School 1 has the lowest peak value of 0.0156kW/m² and school 5 has the highest demand of 0.026kW/m², using Wednesday as a reference. It is interesting to note that in Figures 5 and 6, school 5 has had the smallest average energy profile, yet in Figure 7 has the largest demand profile. Ideally it would be best to plot all 365 for all five schools days to get a better insight into how energy is consumed in each school. However to plot over 1,825 profiles on one chart, or alternatively 5 plots on 365 charts, would be impractical, hence using average week profiles as a fair compromise. An interesting discovery is that several of the schools appear to have some energy activity at the weekends. This is most likely due to the schools offering Saturday activities/classes such as swimming or social clubs. This can be confirmed by referring to Table 3 that highlights the studied school’s weekend opening hours.
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Figure 8 – Average Seasonal Week Profiles for School 3
Figure 8 demonstrates the average weekly profiles for school 3 for each of the seasons. The profiles have not been normalised by floor area as there is only one school’s demand being plotted, as opposed to several schools. The figure highlights the seasonal variation in energy demand during the different seasons. It can be seen that autumn and spring have the largest profiles, with each having an average peak demand of 139kW and 128kW, respectively. The summer and winter profiles have peak values of 101kW and 98kW respectively. If these profiles are compared with the office profiles, shown in Figure 4, it can be seen that the school energy patterns are quite different. Figure 4 demonstrates that the office has a higher electricity demand in winter, has the lowest demand in summer, and has roughly the same demand for autumn and spring, which falls between the demands of winter and summer. Generally an office will stay open throughout the year, with the occasional bank holiday, or seasonal holiday, where the building is closed. In contrast, schools generally have Easter, summer and winter holidays, when the school can be closed for several weeks. On average, a school can be closed for up to 12 weeks a year, with summer being the longest duration, at around 6-7 weeks. This would account for why the average summer profile is smaller than autumn/spring. Figure 8 also demonstrates the difference in average seasonal baseloads. A further step would be to filter out the days when the school is not in use, i.e holidays, to allow a fairer seasonal comparison of actual working days. Autumn and summer have an almost identical baseload value of 26kW. Winter and spring have a higher baseload, of 46kW and 35kW respectively, though this could be due to the increase use of standby lighting and heating pumps. Conclusion The primary objective of this study was to introduce an investigation into demand profile patterns for non-domestic buildings, and whether such patterns can (with appropriate data) be generalised. The initial analysis of office and school data demonstrated that there are several hurdles that have to be overcome in order to create such generalised profile and benchmarks. The first part of the analysis involved creating average daily demand profiles as shown in Figures 1 and 5. The problem with these profiles is that it only gives a basic insight into the electricity demand of each building, and is not useful in comparing the buildings. To overcome this problem, the profiles were normalised by total floor area, to remove the size factor of each building. The effect of normalising the data was that the profiles became more consistent with each other, with the baseload values (except one office) showing similar values. The same was true of the school data. The results from analysing the normalised profiles, was that the buildings need to be grouped into different categories, to allow better comparison. Offices 2, 3 and 4 appear to have the same baseload, compared to office 1 which has almost double the baseload. If building details are compared, office 1 has an older construction, whereas the remaining offices are modern built buildings. In comparison, it was the second oldest school that has the lower normalised baseload, with the other schools having a similar and higher
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baseload to each other. This suggests that the approach of normalising data by suitable variables, of which floor area is just one, might be appropriate for half-hourly electrical demand profiles. An interesting observation made was the size of the average baseloads of the studied schools. The recorded average baseloads ranges from 30kW to 75kW, or alternatively 0.0029-0.0054kW/m². In the case of schools 1 and 3, a small proportion of this is due to constant temperature pumps for keeping the pools heated. These pumps operate throughout the day and night to maintain the pools temperature. The pools are covered at night to reduce heat loss, hence reduce the amount of energy needed to maintain the pool’s temperature. It would be ideal to turn the pumps off and only engage them when the pool was being used, or slightly before the school opened. A further issue with swimming pools is that they require constant ventilation to reduce condensation and require the pool room to be several degrees above the pool temperature to also reduce condensation. The extra ventilation and heating requires fans and heating pumps active during the night. The possible explanations of high baseloads on the schools that do not have swimming pools include emergency lighting, aesthetic building lighting, heating pumps being used and computer servers and associated cooling. The results from analysing both the office and school data highlighted the importance of gathering operation data and opening hours of a building. Figures 2 4 6 and 7 demonstrate that each of the buildings have different profile shapes, dependant on when the buildings are open. Generally offices adopt a 9am-5pm workday and with limited after work activities, although some companies might offer Saturday as a half-day workday. Figure 4 confirms that the buildings are not used appreciably outside the working week. This data is also useful in identifying the appliances and equipment that are switched off when not in use (which might be used as a variable defining the level of energy management in that building). The figure also shows the different opening and closing times of the individual buildings. This effect is also seen in the school data, shown in Figure 6, where schools can have the same basic opening hours, such as 8am-4pm, but the activity in the evening can be different. Future Work As discussed in the “benchmark data” section, there are several identified factors that can influence building energy consumption. To better understand energy use, and hence create more accurate generalised profiles, these influencing factors were also recorded. As mentioned in section 1, climate can have a large impact on a building’s energy consumption. To normalise with climate, weather data for the same year is required. This data can be found in historic climate files, or recorded airport data. One possible problem with using general weather data is that the studied buildings are not located near each other. Using airport weather data, or other available historic climate files, could offer a general overview of a city’s climate. However this data only provides an insight into the climate surrounding the recording station. Onsite weather stations, used in this study, allow for the specific micro-climates to be analysed and ultimately investigate how “climate sensitive” two buildings are. Two weather stations were purchased and placed on two of the studied buildings. The Vantage Pro2 weather station has the ability to record several climate variables, including; outdoor temperature, outdoor humidity, rainfall, solar energy and wind speed. To match the resolution of the electrical demand data, the stations were set to record all data at half hourly intervals. This data will be used in conjunction with the gathered electricity data to determine any trends. A further step in the analysis of the data would be to normalise the energy use with other variables such as the number of workers present during the day. However, the “number of occupants” is not completely independent of floor area, so the results might be expected to be similar. There is an argument that occupant density (i.e. number of occupants per unit floor area) might provide improved normalisation across different buildings. This is currently being investigated, with data pending for several of the buildings being studied. It is not statistically appropriate to state building stock energy demand conclusions based on only a small data set. Studying only five schools and four offices only provides a small ‘snap-shot’ of building energy usage. Any trends identified or general profiles discovered, may not represent the entire school building. Ideally more schools, offices and other non-domestic buildings are needed to help with analysis and to further indentify trends in energy use. There is the possibility of having access to another 20 schools and several more office buildings to assist in future data analysis. The analysis of office and school data that has already been carried out highlighted several building characteristics that have to be recorded and taken into account. These characteristics include; whether the building has a pool (mainly schools), number of elevators, is there evening or weekend usage, does the building have air conditioning, is there mechanical ventilation and how the building is heated (including what type of heating pumps are used, fixed speed/variable speed). The awareness
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of these characteristics will have an important part in determining generalised profiles for a variety of non-domestic building types. References [1] Pe´rez-Lombard L, Ortiz J , Pout C. A review on building energy consumption information, Energy and Buildings, 40 (2008) 394–398, available from www.sciencedirect.com [2] Energy Consumption Guide – 19 (ECOG19), Energy Use in Offices, Carbon Trust publication, (2003), available from www.carbontrust.co.uk. [3] Good Practice Guide - 343 (GPG343), Saving Energy – A whole school approach, Carbon Trust publication, (2008), available from www.carbontrust.co.uk. [4] Lam J C, Chan R.Y.C, Tsang C.L., Li D.H.W, Electricity use characteristics of purpose-built office buildings in subtropical climate, Energy Conversion and Management,45 (2004) 829– 844, available from www.sciencedirect.com [5]
Junnila S, The potential effect of end-users on energy conservation in office buildings, Facilities, 25(7) (2007) 329-339, available from www.emeraldinsight.com
[6]
Dimoudi A, Kostarela P, Energy monitoring and conservation potential in school buildings in the C’ climatic zone of Greece, Renewable Energy, 34 (2009) 289–296, available from www.sciencedirect.com
[7]
Hernandez P, Burke K, Lewis J, Development of energy performance benchmarks and building energy ratings for non-domestic buildings: An example for Irish primary schools, Energy and Buildings 40, (2008) 249–254, available from www.sciencedirect.com
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Regular survey on energy consumption in the tertiary sector in Germany Barbara Schlomann1, Edelgard Gruber2, Bernd Geiger3, Heinrich Kleeberger3, Till Herzog4 ,2 3 Fraunhofer Institute for Systems and Innovation Research (Fraunhofer ISI) IREES , IfE-Technical 4 University Munich, GfK Marketing Services
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Abstract Within the project, which is described here, two surveys on energy consumption were carried out for the years 2004 and 2006, both comprising face-to-face interviews in more than 2000 companies and institutions. As a result, the study provides energy consumption data differentiated by 12 sub-sectors and 6 energy sources which can serve as the basis for efficient and improved examination of the development of energy consumption structures in the tertiary sector. Because the survey has now been repeated, it was also possible for the first time to compile comparable time series over a longer period - 2001 to 2006 - for energy consumption in the tertiary sector by branch and energy source for Germany. This provides another source of information on energy consumption in the tertiary sector which promises to be interesting for international comparisons. On top of this, there is also a differentiated determination of energy consumption by end-uses at sector level for 2006. Above and beyond pure energy statistics, comprehensive sector-specific insights can also be gained from the survey regarding energy consumption structures, energy-relevant features, economic framework conditions and energy management in the commercial building which can be used for numerous other purposes, for example, designing energy policy measures or structuring the advice given by energy agencies, energy consumer associations and energy supply companies.
Starting point and objective In 2008, 1404 PJ or around 15.4% of the total final energy consumption in Germany were accounted for by the tertiary sector [1]. Efforts have been made for several years now by Germany and other countries as well as at the level of the EU and the IEA to record the energy consumption of this very heterogeneous sector or parts of its energy consumption more precisely and in more detail. The EU Directive on energy end-use efficiency and energy services (2006/32/EC; ESD) places high demands on the availability of energy statistics. Public institutions, which make up a subsector of the tertiary sector, are assigned an exemplary role in improving energy efficiency in the ESD. A comprehensive survey of energy consumption in the tertiary sector in Germany was already done in the mid nineties [2]. Another survey for 2001 with a comparable methodology led to a further improvement of the database for this sector [3]. The new survey [4], which is described in this paper, offered the chance to further develop an efficient survey and evaluation method which actually motivates those affected and gets them involved. This method makes it possible to illustrate the main consumption and structural data in the tertiary sector by consumer group and application and to compare these data with the results of the previous survey. This should further improve the energy statistics for this heterogeneous sector and satisfy the requirements for information about energy.
Definitions and Methodology The energy consumption sector "trade, commerce, services", i. e. the tertiary sector, is defined in the same way as in the German national energy balances [1]. From manufacturing industry, the energy consumption of small firms and enterprises with up to 19 employees (small industrial enterprises) is assigned to the tertiary sector. These enterprises are therefore also included in the survey conducted here. Demarcation is performed using the German national classification system based on sectors of the economy (WZ 2003 corresponding to NACE Rev.1.1) and the size of workplaces in the
manufacturing industry (
