in major cities, like in Jakarta, are encouraged to meet that criterion. Three hypothetical office building models are created and simulated to obtain the Energy ...
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ScienceDirect Procedia Engineering 170 (2017) 320 – 324
Engineering Physics International Conference, EPIC 2016
Identification of existing office buildings potential to become green buildings in energy efficiency aspect Anisaha, I. Inayatia, FX. N. Soelamia, R. Triyogoa a
Department of Engineering Physics, Bandung Institute of Technology, Indonesia
Abstract The rise of the issue of climate change and the energy crisis makes the building must perform energy saving measures in order to reduce the adverse effects on the environment. Green Building Council Indonesia (GBCI) has set the criteria named Greenship for Green Building, including on aspects of Energy Efficiency and Conservation that with regard to energy consumption savings. High-rise office buildings located in major cities, like in Jakarta, are encouraged to meet that criterion. Three hypothetical office building models are created and simulated to obtain the Energy Efficiency Index (EEI) and then classified into intensive, standard, and efficient cases. Alternative savings are then applied in simulation to meet the Greenship which is divided into two categories, namely saving alternatives without cost such as changing room temperature setpoint, air conditioning operating schedule, and chilled-water setpoint and alternative savings with cost such as replacement of lamp, glass, and chiller, window film installation. These efforts can produce big savings of EEI up to 40% with the attainment of maximum Greenship score of 36.
© 2017 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license © 2016 The Authors. Published by Elsvier Ltd. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the Engineering Physics International Conference 2016 Keywords: existing office building; green building; EEI; building energy simulation
1. Introduction Buildings become one of the largest contributors of greenhouse gases, namely CO2 into the environment by 40%, causing global warming and climate change [1]. In addition, 48% of the total supply of energy in the world is consumed by the building [2]. In Indonesia, Green Building Council Indonesia (GBCI) has formulated criteria of green building named Greenship which has some aspects of assessment, one of these is the aspect of Energy Efficiency and Conservation (EEC). This aspect dominates Greenship score with a total score of 36 out of maximum 117 or 30% of the maximum score. Meanwhile, Jakarta has the largest number of high-rise buildings in Indonesia and 30% of them are office buildings. Looking at this Greenship, then existing office buildings are encouraged to meet the Greenship and be awarded as green buildings. Various efforts can be carried out which result in energy saving potential achievement levels. The purpose of this study was to determine the saving potential achievement levels of the existing office buildings to meet the EEC Greenship rating system. 2. Theory Green building criteria includes six aspects, namely Appropriate Site Development, Energy Efficiency and Conservation, Water Conservation, Material and Resource Cycle, Indoor Health and Comfort, and Building and Environment Management. Performance indicator of the energy use in a building is measured in Energy Efficiency Index (EEI). The Greenship set the minimum value of EEI of 250 kWh/m2/year for existing office buildings [3]. EEI formula can be written as follows:
( 1)
1877-7058 © 2017 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the Engineering Physics International Conference 2016
doi:10.1016/j.proeng.2017.03.040
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Anisah et al. / Procedia Engineering 170 (2017) 320 – 324
In office buildings, commonly 50 – 60% of the total energy consumption dominated by the air conditioning system (AC). Cooling load in the buildings consists of external and internal loads. The external load includes heat into the room through the building envelope. Factors affecting the amount of external loads are type of construction materials, Window to Wall Ratio (WWR), U-value and Solar Heat Gain Coefficient (SHGC). WWR is the ratio of window area to the total area of the building envelope, U-value shows the amount of heat conduction through the wall and SHGC denotes the amount of incoming solar radiation through the glass material. Internal load comes from lighting system, occupancy, and electrical equipments. The EEI and cooling load of the buildings can then be calculated using Energyplus software. 3. Data and Simulation 3.1. Hypothetical existing office building The first step of this study is modeling the building. The hypothetical building models are built identical and divided into three cases according to the Greenship criteria, namely : 1. 2. 3.
Building with EEI over 300 kWh/m2/year (intensive case) Building with EEI between 250 – 300 kWh/m2/year (standardach case) Building with EEI less than 250 kWh/m2/year (efficient case)
The model is square shaped consisting of 30 floors with dimension of 44 × 44 meters. The total floor area of the building is 58,080 m2.
Fig.1. Floor plan of hypothetical building model
Figure 1 shows the floor plan of the building model which consists of lobby in the 1st floor and office areas from 2nd to 30th floor. Corridor is set as unconditioned area. The next step is determining external and internal load inputs for the model. The input values are determined from Indonesian National Standard (SNI), ASHRAE, and a survey result from existing office building in Jakarta. The building envelope characteristics is shown in Table 1 and Table 2. Table 1. Building envelope materials and characteristics [4] Construction
Material
Wall Bata Celcon + Plaster Plaster
Roof Heavy roof concrete F05 Ceiling air space resistance Gypsum
U-value (W/m2.K)
2.402
1.901
Floor Floor ceramic F05 Ceiling air space resistance Lightweight concrete 1.184
Ceiling Lightweight concrete F05 Ceiling air space resistance Floor ceramic 1.184
Table 2. Glass materials and characteristics [5] Building case Construction U-value (W/m2.K) SHGC Visible transmittance
EEI > 300 Clear glass 8mm 4.94 0.82 0.89
Furthermore, internal load input for the model is shown in Table 3.
EEI 250 – 300 Tinted glass 5.8 0.6 0.57
EEI < 250 Low-e glass 4.54 0.4 0.57
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Anisah et al. / Procedia Engineering 170 (2017) 320 – 324 Table 3. Lighting, occupancy, electrical equipments characteristics [6,7] Lighting system Type of lamp Office area and lobby light power density Corridor light power density Occupancy Office area occupant Lobby occupant Activity level Electrical Equipments Office appliance power density Lobby appliance power Elevators power
TLD 36 W + Magnetic ballast 9 W 15 W/m2 10 W/m2 10 m2/person 20 m2/person 150 W/person 10.8 W/m2 3,000 W 312,000 W
AC system that is applied to the model uses variable air volume system with cooling tower as condenser. Coefficient of Performance (COP) of the system is 4, chilled-water setpoint of 6.7 oC and infiltration rate of 1 cfm. In addition, each cases apply different thermostat setpoint, 21 oC for intensive case, 22 oC for standard case, and 24 oC of efficient case. The models are then simulated to determine the initial value of EEI and the energy consumption distribution. 3.2. Saving alternatives design After the model is made and simulated, the saving alternatives to improve the building energy performance are designed. The alternatives are derived from survey result of an office building in Jakarta which has been certified as a green building and other references to be used as guidelines. The designed saving alternatives consist of two categories, saving alternatives with and without cost. The saving alternatives without cost are : 1. 2. 3.
Increasing thermostat setpoint from existing setpoint to 25 oC Changing the AC system operation schedule from 06.00 – 18.00 to 08.00 – 18.00 Increasing chilled-water setpoint in chiller from 6.7 oC to 7.1 oC
The saving alternatives with cost are : 1. 2. 3. 4.
Replacement of lamp into energy saving lamps such as T5 and LED Installation of window film with various lower SHGC Replacement of glass material Chiller replacement with high COP
These alternatives are applied to the model with single parametric run method which applies one parameter at a time, and then identify the percentage of EEI reduction. 4. Results and Discussion The initial simulation for three building model cases result in EEI value of 301.47 kWh/m2/year for intensive case, 266.87 kWh/m2/year for standard case, and 228.23 kWh/m2/year for efficient case. The energy consumption distribution for each case is shown in Figure 2.
Anisah et al. / Procedia Engineering 170 (2017) 320 – 324
Fig.2. Energy consumption distribution for three case building models
It can be seen from Figure 2 that the energy consumption in the three cases of the building is dominated by AC system, followed by lighting system, electrical equipments, and elevators. However, the AC percentage is different in the three cases because the difference of the glass material and thermostat setpoint. In intensive case, the glass used is clear glass with highest SHGC value and it has the lowest thermostat setpoint that causes the AC system to consume the most electricity. Otherwise, for efficient case, it has already built with energy efficient glass material with the lowest SHGC value and it has the highest thermostat setpoint, so it consumes the least electricity. Furthermore, other simulations are done by applying the saving alternatives that have been designed. The simulation results throughout the implementation of those saving alternatives is shown in Figure 3.
Fig.3. Percentage of EEI reduction by applying saving alternatives
The saving alternatives that offer the greatest saving are lamp replacement with LED and chiller replacement with high COP chiller, these give about 11 – 14% EEI reduction. The saving alternative with minimum EEI reduction is changing the AC operation schedule, this effort gives around 0.7% reduction. Meanwhile, replacement of glass material or applying window film provides more significant impact in intensive case than that in standard case. Initially, glass material in intensive case is made by clear glass with high SHGC value of 0.8, whereas SHGC in standard case is 0.6. It is found that reducing SHGC in standard case has a lower impact than that in intensive case. In the glass replacement alternative, low-e glass has the biggest EEI reduction, while in the window film installment, the window film-1 has the largest saving. Both low-e glass and window film-1 have the lowest SHGC value among the others. Generally, saving alternatives without cost will decrease EEI below 5%. For efficient case, less saving alternatives can be applied than the other cases because it normally already implementing energy conservation principles.
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Furthermore, next simulations were carried out by simulating some case studies. The case studies are composed of several saving alternatives to see the impact of these saving alternatives combination to the building energy performance. The case studies are divided into two groups, minimum case consists of saving alternatives with minimum EEI reduction (lowest investment cost) and maximum case which consists of saving alternatives with maximum EEI reduction (the highest invenstment cost). The detail of each case studies can be seen in Table 4. Table 4. Detail of saving alternatives combination for minimum and miximum case Minimum case Increasing setpoint Changing AC operation schedule Increasing chilled-water setpoint Replacement of chiller with COP 5 Replacement of lamp to T5 Replacement with tinted glass (except for efficient case)
Maximum case Increasing setpoint Changing AC operation schedule Increasing chilled-water setpoint Replacement of chiller with COP 6.05 Replacement of lamp to LED Replacement with tinted low-e glass (except for efficient case)
The result of simulation by applying the cases is shown in Table 5. Table 5. Simulation result of minimum and maximum case studies
EEI reduction Greenship score
Minimum case EEI > 300 24.15% 28
EEI 250 – 300 22.8% 26
EEI < 250 19.41% 28
Maximum case EEI > 300 39.76% 36
EEI 250 – 300 35.27% 36
EEI < 250 28.53% 36
From Table 5 above, it can be explained that the maximum case has greater decrease of EEI value in the range of 28 – 40% compared to the minimum case at a range of 19 – 24% from its initial EEI. However, the initial investment cost for maximum case implementation is also greater than that in the minimum case. For Greenship score attainment, the building model that applies maximum case could obtain the highest score in EEC aspect of 36. Otherwise, the minimum case implementation could obtain maximum score of only 28 from 36. So, the building that applies maximum alternatives would have a greater potential to be awarded as a green building. 5. Conclusion Based on the results and discussion of three case models that represent the office buildings in Jakarta it can be concluded as follows : •
•
The potential of existing office buildings in Jakarta to become green buildings can be simulated which results : a. Saving alternatives without cost resulting in EEI reduction of 3 – 8% b. Saving alternatives with cost resulting in minimum EEI reduction of 19 – 24% and maximum EEI reduction of 28 – 40% The saving alternatives that can be applied to the building have different saving potentials. The alternative that has the greatest saving potential is replacement of lamp into LED lamp, whereas the least saving potential is changing AC operation schedule.
References [1] J. Yudelson, Green Building A to Z: Understanding the Language of Green Building. Kanada: New Society Publishers, 2007. [2] N. Adiwoso, “Towards Indonesia’s Sustainable Future through Sustainable Building and Construction,” presented at the Conference on Sustainable Building South East Asia, Kuala Lumpur, Malaysia, 2010. [3] Divisi Rating dan Teknologi Green Building Council Indonesia, “Greenship Existing Building Version 1.0: Ringkasan Tolok Ukur.” Green Building Council Indonesia, 2011. . [4] G. Bagaswara and M. R. Kurniawan, “Penentuan Intensitas Konsumsi Energi pada Bangunan Kantor Tipikal di Indonesia dengan Menggunakan Simulasi Energy Plus,” Institut Teknologi Bandung, Bandung, 2015. [5] Pemerintah Provinsi DKI Jakarta, Panduan Pengguna Bangunan Gedung Hijau Jakarta: Selubung Bangunan, vol. 1. Jakarta: Dinas Pengawasan dan Penertiban Bangunan Pemerinth Provinsi DKI Jakarta, 2013. [6] Badan Standardisasi Nasional, “SNI 03-6575-2001 tentang Tata Cara Perancangan Sistem Pencahayaan Buatan pada Bangunan Gedung.” 2001. [7] W. Rudoy and J. Cuba, ASHRAE Cooling and Heating Load Calculation Manual. United States of America: ASHRAE, 1980.
