0961–3218 # 1999 E & FN Spon
Building environmental assessment methods: applications and development trends Drury Crawley1 and Ilari Aho2 1 US
Department of Energy, 1000 Independence Avenue, SW, Washington, DC 20585-0121, USA E-mail:
[email protected] 2
Motiva, PO Box 462, FIN-02151 Espoo, Finland E-mail: ilari.aho@motiva.
The construction and property sector has seen the development of a number of methods for evaluating the ‘greenness’ of buildings in the 1990s – both for new designs and existing buildings. These range from very detailed life cycle assessment methods, which account for all the embodied and operational environmental impacts of building materials, to higher level environmental impact assessment methods, which evaluate the broader implications of the building’s impact on the environment. In between these two are environmental assessment methods such as BREEAM, BEPAC, LEED, and GBA. In this paper, we discuss the potential market applications of these systems and compare and contrast several of the major environmental assessment methods. Le secteur de la construction et de l’immobilier a eÂte le te moin du deÂveloppement d’un certain nombre de me thodes permettant d’e valuer les performances eÂcologiques des baÃtiments dans les anneÂes 1990, tant sur le plan des nouveaux concepts que des baÃtiments existants. Ces me thodes vont de l’e valuation treÁs deÂtaileÂe du cycle de vie, qui tient compte de l’impact speÂci® que et des incidences ope rationnelles des mateÂriaux de construction sur l’environnement, jusqu’aÁ une eÂvaluation de l’impact environnemental aÁ un niveau plus eÂleveÂ. Entre ces deux extreà mes, on trouve des me thodes d’eÂvaluation environnementale telles que BREEAM, BEPAC, LEED et GBA. Dans cet article, nous examinons les applications commerciales potentielles des ces systeÁmes; nous comparons, en les opposant, plusieurs me thodes majeures d’e valuation environnementale. Keywords: environmental assessment, green buildings, life cycle assessment, building performance, Green Building Challenge
Introduction Throughout the world economy, many industrial sectors are beginning to recognize the impacts of their activities on the environment and to make signi® cant changes to mitigate their environmental impact. The construction and property sector is also starting to acknowledge their responsibilities for the environment ± causing a shift in how buildings are designed, built, and operated. This shift in attitude comes from conscious public policy decisions imposing requirements on industrial and economic activities but also from a growing market demand for environmentally sound products and services. 300
A central issue in striving towards reduced environmental impact is the need for a practicable and meaningful yardstick for measuring environmental performance, both in terms of identifying starting points and monitoring progress. As for any other sector, from the construction and property sector’s perspective this can be divided in two slightly different points of view: measuring the environmental impact of design, construction and property management activities (as services or industrial production processes) and the environmental impact of buildings (as products). From the latter point of view the question is about identifying and quantifying of the environmental impact of the construction, use and eventual Bu i l d i n
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dismantling of a building in a given location and time span. Two basic methodological frameworks have been developed for assessing the environmental impact of a given object: Environmental Impact Assessment (EIA) and Life Cycle Assessment (LCA). In principle both share the aim of objectively inventorying and assessing the environmental impacts of their objects of study, but they differ in one fundamental sense (Fig. 1). In EIA the focus is put on assessing the actual environmental impacts of an object located on a given site and in a given context, whereas LCA is formulated to assess the non-site speci® c potential environmental impacts of a product regardless of where, when or by whom it is used. Thinking about a building as a product, as an object of environmental performance assessment, it becomes clear that buildings fall somewhere in between the strict scopes of EIA and LCA. Buildings incorporate a variety of characteristics of an inherently site and context dependent nature, making buildings from this perspective natural objects for an EIA study. Among the most obvious examples of such characteristics are choices of energy carriers (often at least partly dictated by locally available infrastructure), induced transport requirements to and from the site, buildings’ impacts on surrounding properties etc. On the other hand buildings ± even though extremely complex in comparison with many others ± can be also considered as generic industrial products serving a well de® ned functional need over a de® nable life cycle, thus ® tting also into the scope of LCA. Hence most of the currently applied
Environmental Impact Assessment (EIA) · site and context specific actual impacts on the environment · applied on large capital stock investments, infrastructure projects etc Life Cycle Assessment (LCA) · non site specific potential impacts on the environment · standardized principles (ISO 1404x) · applied on the product level
building environmental assessment methods ± discussed in more detail later ± are in a sense crossbreeds of the two approaches (Bryan, 1998).
Applications for environmental assessment in the building sector Environmental management systems in the real property sector The introduction of environmental management systems, in compliance with the ISO 14000 series standards or the EMAS scheme within the European Union, is also gradually taking place in the property sector. Establishing an environmental management system aims to change an organization’s management practices and operational patterns in order to reach improvements in the environmental performance and, consequently, in the long term business performance of the organization. Among the ® rst steps in establishing an environmental management system (both in terms of ISO 14000 and EMAS) is the conduction of an environmental review of the company’s activities and processes. From a property company’s (be it a developer, property holding company, institutional building owner, etc.) perspective it is (or at least should be) obvious that a major contribution to the company’s total environmental impact comes from the construction, operation and maintenance of the buildings and facilities the company provides to its customers. Hence an environmental state-of-the-art review of a property company should build on an analysis of the company’s property portfolio.
Community
Buildings
Building products and components
Construction materials
Fig. 1. Conceptual differences between environmental impact assessment (EIA) and life cycle assessmen t (LCA). 301
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Building environmental assessment methods, if properly formulated and implemented, provide a good set of tools for this purpose. As the information produced by such a review is (in theory) only intended to serve the property company’s efforts in producing plans and programmes for reducing environmental impact, the methods and tools used do not need to be either standardized nor transparent. From this point of view the only actual requirements on the content of the applied environmental assessment methods are de® ned by the amount, type and quality of information needed to serve the company’s speci® c internal targets.
Public instruments for property marketing The primary intention behind the development of schemes for environmental labelling, rating and declaration of products is to provide consumers with the means for making purchase decisions based on the environmental characteristics of available product alternatives. Industrial and commercial faith (at least in certain sectors) in the market transformation impacts of such schemes is visualized in the fact that there is already a large number of variable schemes existing, developed either for different kinds of consumer product groups or for assessing products from different standpoints. The main difference between the different approaches can be found in the amount of information directly provided to the consumer and in the level of aggregation of this information. Whereas environmental labelling only declares that a product meets certain prede® ned environmental requirements, the idea behind rating systems is to inform the consumer also on the product’s performance relative to available alternatives. Environmental product declarations, on the other hand, provide a structured account on a product’s `environmental content’, but usually do not allow direct comparisons between products because of the disaggregated nature of the information provided. Building environmental assessment methods can in principle be envisaged to apply for all three purposes. (In practice, however, the usefulness to the average consumer of an environmental product declaration of a building might in all its complexity be questioned.) Building environmental labelling or 302
rating schemes exist in a number of countries already or are being developed. Most common examples of such schemes are, of course, BREEAM in the UK and LEED in the US. In order for an environmental assessment method to form an acceptable basis for a public labelling or rating scheme certain fundamental requirements must be met, both from a philosophical and a practical point of view. Methodological transparency is one of the most fundamental requirements. Both consumers and companies operating on the market must be able to access and understand the assumptions, data and other methodological issues in¯ uencing the outcome of assessments and consequent ratings of different buildings. This is a key issue both in terms of the consumers making conscious choices and meaningful comparisons and in terms of building sector companies being able to improve their performance and thus effectively compete on the market. Another important requirement, somewhat related to the above, is that assessments leading to a public rating should in principle be fully performancebased and that they should not include featurebased judgements of the building’s technical characteristics. Rating or labelling buildings on the basis of their technical features (e.g. envelope Uvalues, inclusion of low ¯ ow sanitary ® xtures, inclusion=exclusion of prede® ned materials, etc.) might ® rst of all exclude buildings with certain technical details from obtaining a good rating regardless of the building’s overall performance. Secondly, and more importantly, feature-based assessment inevitably encourages the building sector towards `feature-based design and maintenance’ of buildings and not towards achieving good performance, a fact which obviously is a major contradiction with the fundamental targets of building labelling and rating. In practice, however, tools and methods available for the assessment of many key aspects of building performance (e.g. indoor climate) are currently not developed to the extent that would enable practical, strictly performance based assessments to be made.
Building performance specication and targeting One of the most natural applications of environmental assessment methods is the speci® cation of
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environmental targets for a construction project. However, in addition to having a framework provided by an environmental assessment system, meaningful performance speci® cation also requires a set of benchmarks against which targets are set and ef® cient tools adapted for the clients’ use for verifying the proposed design’s compliance with the targets. Applying the current environmental assessment methods typically requires special `environmental assessment expertise’, and hence are applicable as speci® cation and targeting tools only in larger projects where external expertise can be afforded. The GBA system developed in conjunction with the Green Building Challenge process (described in more detail below) has to a certain extent tried to address this problem by incorporating a `nesting principle’ in its structure. The idea of nesting is to allow the system to be used consistently on different levels of detail, e.g. to be able to assess (or set targets for) energy consumption either on the level of statistically or otherwise derived indicator values, on the level of simulated energy performance predictions for the operations phase or ultimately on the level of full life cycle energy analysis (including cradle-to-grave or lust-to-dust calculations of all building elements and materials, construction site energy consumption). Hence nesting would allow for performance targets to be speci® ed on the highest abstraction level and the compliance of designs with the targets to be veri® ed using methods indicated on the highest level of detail. However, nesting as implemented in GBA needs further development before it serves this purpose in a practicable way.
information on and characteristics of the technical details of the system. How can environmental assessment methods help in design? The primary bene® t from these schemes is that they can provide a structured means of incorporating performance targets and criteria into the design process. An example of this is the nesting principle in the GBA method, already discussed above, which (at least in principle) enables overall criteria to be de® ned and evaluated during the `design-assessment’ process (Fig 2). Design guidelines are of a different nature. The purpose of these is (or should be) to provide (technical) guidance on the interrelationship between technical implementation and performance, e.g., what are the impacts of a technical solution on a performance indicator, how to design and dimension a system to reach a given performance level, etc. Hence the common denominator of design guidelines and performance assessment systems is materialized in performance indicators or criteria. For building design these represent targets, objectives and=or requirements, whereas for performance assessment they represent the basic output of analysis.
Performance based building codes
Even though environmental assessment methods are not originally intended to serve as design guidelines it seems that they, in the absence of better alternatives, are increasingly being used as such.
Development of building codes and regulations has in many countries been directed from featurebased towards performance-based requirements. This is especially the case for building energy codes for which the change is visualized by a shift from regulations concerning, for example, maximum allowable U-values of individual envelope components to regulations on the calculated energy performance of the design. Environmental assessment methods might provide a means for incorporating holistic environmental performance requirements in national building regulations, and thus signi® cantly reducing the environmental impact of new construction.
However, it is important to conceptually separate product design and product assessment. Building design (and systems design in general) is a topdown process in which the original overall concept is being gradually worked towards detailed implementation (Fig 2). Performance assessment, on the other hand, takes place in a bottom-up direction, synthesizing the overall environmental performance of a given design starting from
Verifying the compliance of building designs with the magnitude of existing regulations and norms is a time and labour consuming task, both in terms of the designers producing necessary documentation ± energy and environmental regulations require documentation beyond what is needed for actual construction ± and in terms of local and regional of® cials carrying out the actual compliance veri® cation. With design budgets already constrained,
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construction clients and their designers might not welcome the extra cost of documenting the building’s environmental performance for regulatory purposes. Some countries have already taken steps towards accepting environmental assessment as an alternative route to complying with building regulations. One of the ® rst examples is presented in the current Norwegian building code where compliance with energy performance requirements can be shown not only by using prede® ned envelope insulation levels or providing a calculated energy consumption, but also by performing a (more or less detailed) LCA study on the building and comparing the results with the life cycle energy use of a `standard building’. This, of course, provides a host of new opportunities and degrees of freedom for building design, possibilities which can be used to compensate for the additional cost of carrying out detailed assessments during the project. This could provide an additional incentive for construction clients to take on environmental assessment as standard practice in construction projects. 304
However, it should be noticed that a considerable amount of education and training is needed both on the local and regional authorities’ side and on the design professionals’ side before mandatory instruments can effectively operate on the market. The transition from traditional feature based building codes to performance requirements has already, in the case of energy regulations, turned out to be a large step for both professions.
Environmental auditing of existing buildings The vast majority of the building stock was built in the past and has been in use for several decades, especially in Europe. The focus of construction activities has gradually been shifting from new construction to renovation and refurbishment projects. Also the fact that building stocks in general are renewed at a rate of 1± 2% annually implies that the largest improvement potential in the environmental performance of buildings lies in incorporating effective environmental measures in renovations. Environmental assessment methods in general, and
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the `building inventory’ components contained therein in particular, provide a good starting point for renovation and refurbishment design. Assessment methods can be used both in identifying the most critical components of the environmental performance of existing buildings, in analysing the potential impact of different renovation alternatives and in selecting and implementing the most cost ef® cient measures for environmental improvements.
Examples of existing assessment methods Many of the existing building environmental assessment methods can meet some of the needs addressed in the prior section. In this section, we compare and contrast the appropriate applications and scope of assessment for the four most widely known assessment methods. The scope and application of the assessment methods varies widely; each assessment method is described brie¯ y below.
BREEAM, Building Research Establishment Building Research Establishment Environmental Assessment Methodology (BREEAM) was developed by the Building Research Establishment in the UK and is most widely used of the methods described here. A voluntary, consensus-based, market-focused assessment method, BREEAM uses three scales for environmental impact: global, local, and indoor issues (Prior, 1993). When a building has been evaluated using BREEAM, the result is a single score. Versions of BREEAM have been developed for new and existing buildings in the UK and versions have been or are being developed for Hong Kong, Australia, and Canada.
BEPAC, University of British Columbia Building Environmental Performance Assessment Criteria (BEPAC) was developed at the University of British Columbia and launched in 1993 (Cole et al., 1993). Similar to BREEAM, BEPAC can be used to evaluate the environmental performance of new designs and existing buildings. BEPAC results in a composite weighting of ® ve major areas: ozone protection, environmental impacts of energy use, indoor environmental quality, resource conservation, and site and transportation. BEPAC is primarily used in Canada.
LEED, US Green Building Council Leadership in Energy and Environmental Design (LEED) (USGBC, 1998) was developed through consensus of the US Green Building Council. It will be launched in a pilot programme in 1999 in the US as a voluntary, market-based assessment method intended to de® ne a ’green building.’ In evaluating a building using the LEED criteria, there are minimum, mandatory requirements in areas such as building commissioning, energy ef® ciency, indoor air quality, ozone depletion=CFCs, smoking ban, comfort, and water. Once the mandatory requirements are met, a building can earn `credits’ in 14 areas. Depending on the total credits, a building receives a rating level of `bronze’, `silver’, `gold’, or `platinum’.
GBA, Natural Resources Canada and University of British Columbia The Green Building Assessment (GBA) framework (Larsson and Cole, 1998) was developed to provide a new, common assessment method for evaluating green buildings throughout the world. Thirteen countries used the GBA to compare the environmental features of their `best’ green buildings culminating in the Green Building Challenge ’98 (GBC ’98) conference held in Vancouver in October 1998 (NRC, 1998). Building on the Canadian experience with BEPAC, an international framework committee (IFC) comprising representatives of 13 countries reviewed and developed the GBA. The IFC worked to ensure that the GBA took a comprehensive view of environmental issues within buildings, organizing the assessment in six major areas: resource consumption, environmental loadings, quality of indoor environment, longevity, process, and contextual factors. Further, as described earlier, the GBA used a nesting structure (criteria and subcriteria) to accommodate the large variation in information and detail available on buildings (Cole and Larsson, 1998). The GBA was implemented in a software tool ± the Green Building Tool or GBTool. Data at the individual subcriteria level were compiled in the GBTool for the 34 buildings evaluated for GBC ’98. Each national team developed weighting for subcriteria and criteria, which were applied and composite, weighted scores for the six criteria presented. One of the weaknesses of the GBA is that individual country teams established scoring weights subjectively when evaluating their build305
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ings. Most users found the GBTool dif® cult to use because of the complexity of the framework. We anticipate that these perceived weaknesses will be addressed in adjusting the GBA for use in GBC 2000.
Applications and scope In Table 1, the potential applications described in the previous Section ± Applications for environmental assessment in the building sector ± are used to contrast these four assessment methods ± BREEAM, BEPAC, LEED, and GBA. These are based upon our experience using the four assessment methods. As can be seen in the table, most methods do not meet all the identi® ed application needs for building environmental assessment although GBA comes closest. As found while assessing the 34 buildings for GBC ’98, determining embodied energy was extremely dif® cult and costly. Several countries decided speci® cally not to address it in their assessment. In Table 2, the outline of the GBA method is used (resource consumption, environmental loadings, indoor environment, longevity, process, and contextual factors) to further compare the same four assessment methods. The scopes noted in Table 2 are based with our experience using each of the methods. It is interesting to note that all four methods effectively deal with resource consumption issues. Beyond consumption, they vary in focus and hence, in scope and potential applicability.
Existing (and developing) LCA tools and EIA tools must work better with the assessment methods. International work to develop common assessment methods such as the GBA have revealed many common themes, even if the relative weighting differ signi® cantly from country to country. These methods can be successfully applied at the local, regional, national, and international level through local weighting of the issues the criteria represent. In the end, the combination of these localized weightings to all the environmental issues facing the construction and property sector become that community or country’s valuing of what a green building truly is. Much works remains to ensure that methods provide an objective means of assessing the environmental performance of new building designs and existing building re® t potentials. As the GBA is adapted for use in GBC 2000 and beyond, it may be adapted to ensure objectivity. We see the following four major development paths as vitally important for environmental assessment of buildings: · Methodological development should be directed to address both the assessment of buildings (product assessment) and the assessment of property=construction companies (business process assessment). The ® rst of these approaches is serving the purposes described in this paper. The second line of development ± only brie¯ y touched upon in this paper and even less in actual R&D ± would serve the purposes of environmental management (business process development). Issues that should be addressed include business process modelling from the environmental point of view, de® ning environmental ef® ciency indicators and development of environmental accounting in the real property sector.
Conclusions Signi® cant advances in environmental assessment methods have been seen in the last ten years. However, signi® cant work also remains for tools to support environmental assessment methods. Table 1. Applications of environmental assessmen t methods Assessment method
Application Environmental management
BREEAM BEPAC LEED GBA
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Product marketing
Building performance targeting
Design guidelines
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X X
X X X X
X
Performancebased codes
Environmental auditing in existing buildings X
X
X X
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Table 2. Scope of environmental assessmen t methods Scope
Resource consumption Embodied energy Operation energy Land Water Materials Environmental loading Airborne emissions Solid Liquid waste Other loadings Indoor environment Air quality Thermal quality Visual quality Noise and acoustics Controllability of systems Longevity Adaptability Maintenance of performance Process Design and construction Building operation Contextual factors Contextual factors Loads on immediate surroundings
· Full consistency between materials LCA, building products LCA and building assessment should be assured through combined effort of the research communities involved in these ® elds. Current (and most likely also future) building assessment methods rely more or less blindly on the results of full LCA studies on building materials and components, which naturally means that con® dence in the applicability of such results must be extremely high. · Design guidelines for green buildings are clearly needed in the market. The fact that the demand for guidelines for the design of green buildings has not yet been met in a satisfactory manner has resulted in many of the current assessment methods, such as BREEAM, being used in practice as design guidelines. · There is a clear need for new development methods for `community assessment’. Incorporating community related issues (e.g. transport implications) into building assessment
Assessment method BREEAM
BEPAC
LEED
GBA
X X
X X X X X
X X X X
X X X X X
X X X X
X X X
X X
X X X
X
X X
X X X X X X X X X
X
X X
X X
X
X X
X
X
X X
schemes has proven to be problematic both from the theoretical point of view and practice, and might even in some cases lead to wrong conclusions.
References Bryan, H. (1998) Ef® cacy of environmental assessment systems in addressing energy concerns, in Conference Proceedings of the 23rd National Passive Solar Conference, June, Albuquerque, New Mexico, USA, pp. 305± 311. Cole, R.J., Rousseau, D. and Theaker, I.T. (1993) Building Environmental Performance Assessment Criteria: Version 1 – Ofce Buildings, December. The BEPAC Foundation, Vancouver, Canada. Cole, R. J. and Larsson, N. K. (1998) GBC ’98 Assessment Manual: Volume 1, Overview, April. Natural Resources Canada Ottawa, Canada. Larsson, N. K. and Cole, R. J. (1998) GBC ’98: context, history and structure, in Conference Proceedings, Green Building Challenge ’98. October. Vancouver, Canada. Natural Resources Canada, Ottawa, Canada, pp. 15± 25. 307
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Natural Resources Canada (1998) Conference Proceedings, Green Building Challenge ’98. October. Vancouver, Canada Natural Resources Canada, Ottawa, Canada. Prior, J. (ed.) (1993) Building Research Establishment Environmental Assessment Method (BREEAM), Ver-
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sion 1=93. New Of® ces, Building Research Establishment, Garston, United Kingdom. US Green Building Council (1998) LEED Buildings Green Building Rating System Criteria, US Green Building Council, San Francisco, California.
