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A technical review of energy conservation programs for commercial and government buildings in Thailand
Energy Conversion and Management 44 (2003) 743–762 www.elsevier.com/locate/enconman
A technical review of energy conservation programs for commercial and government buildings in Thailand Surapong Chirarattananon *, Juntakan Taweekun Energy Program, Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathumthani 12120, Thailand Received 15 October 2001; accepted 20 March 2002
Abstract This paper examines the requirements for designated buildings and the mechanisms for implementation of energy conservation programs in accordance with the Energy Conservation Promotion Act of Thailand. It then reviews the details of energy audits and implementation of energy conservation of designated commercial buildings and small government buildings. Through use of the DOE-2 simulation program and reference building models developed from energy audit information, it is shown that whole building retrofit is more cost effective than adopting individual options. It also points out that mobilizing involvement of the occupants of a building is a necessary and integral part of a successful energy conservation program. The paper also suggests means to overcome the present impediments to successful implementation of the programs. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Energy conservation; Energy simulation; Overall thermal transfer value; Energy performance of buildings; Energy audit
1. Introduction The elasticity of energy use to gross domestic product in Thailand, a country in the tropical region of Southeast Asia, averaged 1.12 for the earlier two decades despite past energy conservation policies adopted by the state [1]. In commercial buildings, air conditioning has reached saturation. There has been an increasing use of curtained wall design for large commercial
*
Corresponding author. Tel.: +66-2-524-5437; fax: +66-2-524-5439/6589. E-mail address: [email protected] (S. Chirarattananon).
0196-8904/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 1 9 6 - 8 9 0 4 ( 0 2 ) 0 0 0 8 2 - 1
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buildings. These buildings use glazings of low shading coefficient and low visible transmittance so that very little daylight can enter, and each building relies heavily on electric lighting. In earlier times, air conditioning was not allowed, but by the early 1990s, air conditioning had penetrated all government buildings. A few rooms or a few enclosed spaces in a typical government building would be conditioned by small stand alone, split-type (each with a separate condensing unit and a separate fan coil unit) air conditioners. In 1992, the Thai government promulgated an Energy Conservation Promotion Act (ECP Act) to promote energy conservation and development of renewable energy in a comprehensive way. The priority segments for energy conservation included large commercial buildings and government buildings. A fund for promotion of energy conservation (ECP Fund) was also formed under the ECP Act. The fund receives US$30–70 millions (M) per year, mainly by collection of a levy on domestic consumption of oil. The ECP Fund has been used to engage consulting firms to conduct energy audits on over 1000 designated commercial buildings. It has also been used to support energy audits and retrofits of 573 small government buildings. The options for improvements and retrofitting of these small government buildings are identified by the energy auditors and generally approved by the relevant authorities. In calculating the energy savings from an option, approved engineering calculation procedures are used. These straightforward calculations are simple but neglect the interactive effects of different measures. This paper briefly describes the provisions and requirements of the ECP Act relevant to designated commercial buildings. It then outlines the organization and management of programs for energy conservation in designated commercial buildings and in the small government buildings of relevant agencies. The paper examines the options for energy conservation in these buildings as suggested by the consultants and agencies and, additionally, those deemed appropriate by the authors for application in tropical climates. It then utilizes a well known energy simulation program to calculate the size and cost of the energy savings of each of the reference options, as well as those additional options. The results show that many additional cost effective options for energy conservation should be adopted. Some of these options may involve technologies unfamiliar to local professional societies. The results find the whole building approach to be more cost effective than adopting individual retrofit options. The study also examines successful cases and suggests that building occupants must be involved for a program to achieve real sustained success. The paper also discusses some adverse conditions and impediments to furthering the success of the energy conservation efforts in Thailand.
2. Requirements and the implementation of the ECP Act As has been reported earlier, one objective of the ECP Act was to improve the energy efficiency in buildings [2]. A royal decree was issued in 1995 to designate buildings for compliance with the mandatory requirements of the Act as being those whose electric power and/or equivalent energy demand exceed 1 MW. In the same year, the detailed requirements on designated buildings were announced as a set of ministerial regulations or by-laws of the ECP Act.
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2.1. Requirements on designated buildings The average lighting power for an office, a hospital or a hotel building must not exceed 18 W m2 . For a department store or retail store building the amount is 23 W m2 . For a new building, the overall thermal transfer value (OTTV) of the walls must not exceed 45 W m2 , and for an existing building, the value is 55 W m2 . For the roof, the value is 25 W m2 . There is a detailed set of requirements on the rated power per unit capacity (kW/RFT, refrigeration ton) of air cooled and water cooled chillers of different sizes. The OTTV is devised as a measure of the thermal performance of the building envelope of air conditioned buildings. A set of calculation procedures and property values are given for evaluating the OTTV of a building as a part of the by-laws of the ECP Act. The OTTV formulation has been validated earlier [3]. 2.2. Implementation of the ECP Act A Committee for administering the ECP Fund (ECP Fund Committee), chaired by the prime minister or a deputy prime minister, has been set up in accordance with the ECP Act. The committee appoints three subcommittees. One subcommittee is tasked to assist in the allocation and award of funding for works related to the mandatory requirements of the ECP Act. The other subcommittees oversee funding for the rest of the works under the ECP Act. These include research and development, demonstration, promotion of renewable energy, public relations and human resource development. Each designated building is required by law to engage a consultant to conduct the energy audit, set up the plan and target for energy conservation and to implement the plan to satisfy the requirements of the ECP Act and its by-laws. Funding is available to cover most of the costs of the consultancy, with a total amount available up to 0.6 MB (equivalent to about US $15,000) for each designated building. Funding to cover parts of the cost of retrofit is also available under some conditions. By the early part of 2001, almost all of the 1000 designated buildings have been audited [4] but none has been reported retrofitted for energy conservation under this scheme. The Department of Energy Development and Promotion (DEDP), a government department within the Ministry of Science Technology and Environment, is entrusted by the ECP Act to conduct works related to the mandatory requirements. The energy audit report and plan for improvement for each designated building must be approved by the DEDP for funding to be disbursed. Large government buildings are also subject to the requirements of the ECP Act, but funding can be extended to retrofitting if the resultant internal rate of return of savings exceeds 9% for each building. However, no time frame is set for the management of these government buildings to comply with the requirements of the ECP Act, so the status of the development has not been assessed. A project for retrofitting small government buildings (those whose power demand exceed 100 kW but less than 1 MW) was also created in 1995. By April 2001, 573 of such buildings have been completely audited and retrofitted at a total cost of US $40 M. The objective and funding conditions for retrofitting these buildings are the same as those for large government buildings, but the works were performed by agencies of state universities with close supervision by the DEDP [4].
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3. Energy audits and implementation of energy conservation for designated commercial buildings and small government buildings For the designated commercial buildings, the premise is that the direct beneficiaries of energy conservation are the building management, and so, they should be responsible primarily for the costs of retrofits. For government buildings, it is perceived that the public is the eventual beneficiary, so the state can invest in retrofitting government buildings. 3.1. Designated commercial buildings A private consultant would be chosen by the management of a building from a list of registered consulting companies given by the DEDP. The consultant would typically conduct a field (onsite) energy audit of the building. The items of information a consultant files in the energy audit report are shown in Table 1. From the details obtained on the building dimensions, orientation and construction, a consultant would calculate the wall OTTV and the roof OTTV of a given building. The monthly electric energy (kW h), peak power consumption (kW) in peak, partial peak and off-peak periods and value of power factor are obtainable from the electric bill of a building. In the course of an Table 1 Information items in the energy audit report on a commercial building Item Type, location, age
Detail
Office, hotel, etc.; city and region; the year construction completed Shape, dimension Photographs and diagrams Orientation North, south etc., azimuth of each facade Construction Composition and area of each opaque wall, thermal properties of wall materials, conductivity, shading devices, etc. Roof details Glazing type and area, shading coefficient, thermal properties Area usage Size of air-conditioned area, unconditioned area, car park Identification of areas classified according to functions: office, guest room meeting room, etc. Energy system and use Electricity: power and energy in major feeders, transformer losses, light and plug load, air-conditioning system Boiler: gas or oil and hot water use Air-conditioning Total design capacity, ratings of components System and effects Measured indices: COP of chillers, system COP, temperature and relative humidity in each zone, air enthalpy Lighting system and effects Lighting devices: type and rating in each area, illuminance in an area Equipment Central service equipment (e.g. lifts) Equipment in air-conditioned areas, etc.
Unit (when applicable) Y m degree m, W m1 K1
m2
kW, kW h
l, MJ RFT, m2 /RFT, kW, °C, %, kJ kg1 W, W m2 , lux kW kW, W m2
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audit, a consultant usually carries a set of portable equipment for measurement of electric power, illuminance, relative humidity of air, temperature of air, temperature of water and surfaces of chilled water pipes. The electric power taken by the air conditioning system and the total power of the building are measured as instantaneous values during the time of an audit. The total lighting power is calculated by summing the rated power of all lighting equipment and lamps. The electric power of plug loads and other equipment are calculated by subtracting from the measured value of the building load the measured air conditioning load and the calculated lighting load. The proportionate shares of electric power among the three major categories of loads are then used subsequently to calculate the shares of the monthly and annual cooling and lighting energy of the building. The coefficient of performance (COP) of a water chiller can be obtained from the value of the refrigeration effect, calculated from the known chilled water flow and the measured temperatures of the return and supply chilled water and the measured power taken by the chiller. For a direct expansion air conditioning unit, a similar method can be employed to obtain its COP. Some energy use and performance indices and the ranges of values obtained from energy audits are as shown in Table 2. The audit results confirm the results from earlier studies [2] that typically air conditioning is responsible for 60% of electricity consumption in a commercial building. Heat gain through the building envelope contributes up to 60% of the total cooling load. Electric lighting contributes 20% of the electricity consumption and also contributes up to 20% to the cooling load. Each audit report identifies options for energy conservation and calculates the costs and benefits using rated values and engineering calculations for each option. No interactive effects, such as the corresponding reduction in cooling load to the air conditioning system from reduced electricity use of more efficient equipment is taken into account. Moreover, the calculated reductions in electricity use from different options are simply summed. For example, the use of optical film on glazed windows is estimated to save 40 units of energy. (This is expected to reduce the heat gain and the corresponding cooling energy from the base situation.) Replacing the Table 2 Ranges of values of some energy use and performance indices Item
Office
Hotel
Hospital
Department store
% of area air-conditioned Wall OTTV (W m2 ) Roof OTTV (W m2 ) Energy index (kW h m2 Y1 )
43–100 32–105 3–67 97–350
65–84 33–90 18–45 141–580
36–70 44–74 10–45 104–775
82–100 32–84 60–62 170–480
Air-conditioned area Design coverage (m2 /RFT) Energy index (kW h m2 Y1 ) Chiller COP System COP
10–26 57–160 1.8–5.3 1.5–2.9
9–44 81–112 3.3–4.9 1.5–2.2
7–32 65–207 2.6–4.8 1.7–2.9
11–24 134–210 3.8–5.3 2.3–2.6
Lighting, office space Illuminance (lux) Power density (W m2 ) Energy index (kW h m2 Y1 )
200–520 5–33 19–53
116–218 3–17 28–63
200–360 4–26 19–53
320–440 7–33 17–99
Note: Areas of car park are excluded in calculation of energy use indices.
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existing air conditioner with a COP of 1.75 by another one with COP of 3.0 is estimated to save 40 units from the base case. An energy audit would report a total saving of 80 units. The first option would already reduce the cooling load below the base value, and the following option would save from the new reduced base. The options for energy efficiency improvement suggested in the audits are listed in Table 7 of Section 6. Each energy audit report must be approved by the DEDP before funds can be disbursed. The format of the report, as well as the options recommended, must conform to a standard. Energy conservation options outside of the standard list are not encouraged. Individual schedules and the diversities of use of space, equipment and lighting are not recorded in the audits. 3.2. Small government building project The main objective is to reduce energy use in government buildings and to set examples of good practice on prudent and efficient use of energy to the public. State universities have created extensions or community service units to enhance their services to the public. A number of these units from different universities were appointed as implementing agencies (IA) by the DEDP, each to conduct energy audits and recommend retrofit options on a group of buildings chosen by the DEDP. The same IA would be assigned to supervise retrofitting the same group of buildings for the options approved by the DEDP and the ECP Fund Committee. The format and information items in each report are similar to those filed by the consulting companies (Table 1). However, since the buildings are smaller, all use stand alone, split-type air conditioners. Each report also produces values of the energy use indices. However, values of the energy efficiency ratio (EER) of air conditioners are reported. An EER is the ratio of cooling in the unit of BTU/h produced per unit of electric power (W) taken. Measurements of the speed and the condition of moist air input to and output from an air conditioner are required to obtain the amount of cooling it produces. The typical value of EER obtained for existing air conditioners from the reports is 6. This corresponds to a COP of 1.76. Government buildings are generally old and were not designed for air conditioning. Illuminance levels were also observed to be low. Recommended retrofit options exclude those involving the building envelope, mainly because the areas involved in each building were considered too small and the retrofitting jobs too small to attract building contractors. Most accepted options include replacing air conditioners, installing electronic thermostats (in place of electromagnetic thermostats commonly used earlier), replacing existing fluorescent fixtures by reflective parabolic fixtures, replacing existing magnetic ballasts by electronic ballasts and replacing standard fluorescent lamps (each rated at 36 W and producing 2700 lm) by efficient lamps (each rated at 36 W and producing 3350 lm). So the recommended and approved options include only replacement of air conditioners and luminaires.
4. Methodologies for calculation of energy use in buildings In earlier times, the methods employed to predict energy use in buildings were based on the use of heating-degree hours or cooling-degree hours and steady state calculations [5]. Use of a solar utilizability factor and variable base temperatures and binning of weather data improve the
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prediction of heating and cooling loads and energy use [5,6], but all these earlier methods use the steady state concept and are applicable with sufficient accuracy for buildings with single zone and a regular schedule of use. Large buildings comprise multiple zones, each with separate schedules of occupancy, lighting and equipment use. The interactive effects of different equipment use and the effect on cooling load in air conditioned buildings, as well as the storage effects of the masses of building components must be taken into account. Added to the complexity is the dependence of the performance of the air conditioning system on how the system is operated. Use of sophisticated computer programs is necessary to achieve an acceptable degree of accuracy. A well known building energy simulation program developed under support from the Department of Energy of USA, called DOE-2, was used in this work to simulate the energy use in the designated commercial buildings and in small government buildings. Version 2.1E of the program was used. This program is up-to-date, unbiased, well documented and requires a detailed description of the building construction and schedules of use of equipment, occupancy and space in each individual zone. It also requires hourby-hour weather data. For this study, the weather data of Bangkok was used. Parker et al. used DOE-2 for simulation analysis of different features to improve energy efficiency in the design of an office in the Florida Solar Energy Center under the hot and humid climate of Florida [7]. The simulation results were partially verified one year after completion of the construction of the building. Kim et al. used DOE-2 simulation to evaluate the relative performance of constant-air-volume and variable-air-volume (VAV) air handling systems, an ice storage control strategy and a number of other options for an office building in Seoul, Korea [8]. In Hong Kong, Lam utilized DOE-2 to calculate and compare monthly and annual cooling loads and energy use of a generic building using weather data of different years [9]. Chou and Chang utilized DOE-2 to develop simplified relationships for predicting annual energy use for a number of buildings in Singapore [10]. 4.1. Simulation methodology In order to use DOE-2, a reference building model representing each identified building group is developed based on energy audit data. Baseline information on building characteristics, equipment use and operational schedules, together with weather data, were used with each building model to run DOE-2 to obtain reference cooling load and energy use information. Options for improving energy efficiency were then applied, and DOE-2 was again run to produce comparative outputs for use in comparing and evaluating the cost effectiveness of different options.
5. Reference building models and energy consumption The two groups of buildings require two different sets of reference building models. 5.1. Reference models for designated commercial buildings The ECP Act recognizes four types of commercial buildings. Information obtained from a large number of energy audit reports on commercial buildings was used to construct four reference
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Fig. 1. The shapes of four reference building models: (a) office, (b) hotel, (c) hospital and (d) department store.
building models, each for one type of commercial building. The shapes of the four models are shown in Fig. 1. All are rectangular with the smaller facades facing east and west. The opaque walls of these buildings typically comprise cement plastered brick work. Single glazing is mostly used. Centralized air conditioning systems are used with water cooled centrifugal chillers. Fluorescent lighting is employed in the office space, in corridors and in most spaces of most buildings, except a hotel. Incandescent lamps are used in guest rooms, function rooms and other places in a hotel. The levels of illuminance in hotels are lower than those in other commercial buildings. Table 3 lists the details of the models relevant to the present work. Each model incorporates the most common features of the building type. The length and width of each building are comparable, so that the area of each floor is large and the ratio of total wall area to total floor area of each building is relatively small. As is common, the ratio of window area to total wall area for the hotel is small, while those for other building types are larger. 5.2. Energy use of reference models for designated commercial buildings Summarized annual energy use of the reference models obtained from DOE-2 simulation is shown in Table 4. The percentage share of energy use due to air conditioning, lighting etc. and the value of the energy use index for each building type match with those from the audit reports. 5.3. Reference models for small government buildings Government buildings are rectangular and commonly comprise two stories. The opaque wall is typically constructed from cement plastered brickwork. Single clear glazing is used. Normal operating time is between 8:30 and 16:30 h during weekdays, and the buildings are closed during weekends and holidays. Lighting and equipment power densities are rather low. Most government buildings are old and were originally designed for natural ventilation, but air conditioners have
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Table 3 Details of commercial building models Item
Office
Hotel
Hospital
Department store
Number of stories Total area of opaque walls (m2 ) Total area of glazings (m2 ) Total area of roof (m2 ) Total area of floors (m2 ) Ratio of wall area to floor area Ratio of window area to wall area, WWR Shading coefficient of glazing, SC Overall coefficient of heat transfer for wall, Uw (W m2 K1 ) Overall coefficient of heat transfer for roof, Ur (W m2 K1 ) Solar absorptance of wall and roof surfaces, aw , ar Annual average OTTV (W m2 ) Air handling system Lighting power density (W m2 ) Equipment power density (W m2 ) Interior temperature, Ti (°C) Number of occupantsb per 100 m2 Number of working days per week Working hours Number of zones in DOE-2 simulation Zone 1 Zone 2 (core or podium) Zone 3
12 3883 3051 1421 12,567 0.55 0.44 0.64 2.957
8 3585 734 1080 11,448 0.37 0.17 0.64 2.957
8 3803 1553 1728 17,280 0.30 0.29 0.64 2.957
3 1972 1208 2760 8280 0.38 0.38 0.96 2.957
1.845
1.845
1.845
1.845
0.4 62.32 CAVa 13.18 12.88 25 7 5 8:00–17:00 3 Floor 1 Core Floors 2–12
0.4 56.38 CAV 5.56 2.3 25 20 7 0:00–24:00 3 Floor 1 Floors 2–3 Floors 4–8
0.4 52.78 CAV 10.67 3.36 25 10 7 0:00–24:00 3 Floor 1 Floors 2–3 Floors 4–8
0.4 65.48 CAV 17.48 25.05 25 20 7 10:00–21:00 3 Floor 1 Floor 2 Floor 3
Source: energy audit reports of 1997–2001. a CAV ¼ constant air volume system. b Sensible and latent heat gains per occupant used are 73 and 59 W, respectively. Table 4 Breakdown of annual energy consumption for commercial building models End-use
Office
Hotel
Hospital
Department store
Air conditioning system (kW h) % Share air conditioning Lighting system (kW h) % Share lighting Equipment system (kW h) % Share equipment Total annual energy consumption (kW h) Total annual cooling load (kW h) Energy use index (kW h m2 Y1 )
1,345,612 66.41% 433,918 21.41% 246,807 12.18% 2,026,337 3,005,204 161
1,702,305 86.94% 193,210 9.87% 62,499 3.19% 1,958,014 3,598,488 171
1,893,502 76.05% 491,777 19.75% 104,530 4.20% 2,489,809 3,230,224 144
1,857,109 62.09% 541,034 18.09% 592,969 19.82% 2,991,112 4,039,274 361
been reportedly installed in some enclosed spaces of each building. The air conditioners used are mostly split-type. Three types of buildings are identified from consideration of the size and
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Fig. 2. Government building models.
location of the main air conditioned space. Type 1 represents state enterprise and ministerial buildings, type 2 represents school buildings and city halls and type 3 represents hospital buildings. The details are shown in Fig. 2 and Table 5. 5.4. Energy use of reference models for small government buildings Summarized annual energy use of the reference models for small government buildings are shown in Table 6. The values of energy use indices pertain to the air conditioned space only. The relative share of energy use in unconditioned spaces is much lower in a government building. Natural daylight is used, and occasionally, a small fan is used in most unconditioned spaces. Computers and other electrical equipment are generally housed in an air conditioned room where electric lighting is invariably used. Our attention in the energy conservation effort will be focussed on air conditioned spaces. 6. Evaluation of options for energy conservation 6.1. Options for energy conservation The costs and benefits of the options for energy conservation are assessed in the energy report submitted by the consultant to the management of each commercial building and in the report submitted by each IA for a government building. The lists of these options are given in Table 7.
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Table 5 Details of government building models Parameter
Type 1
Type 2
Type 3
Number of stories Total area of roof (m2 ) Total area of floor (m2 ) Ratio of window area to wall area, WWR Shading coefficient, SC Overall coefficient of heat transfer for wall, Uw (W m2 K1 ) Overall coefficient of heat transfer for roof, Ur (W m2 K1 ) Solar absorptance of wall and roof surfaces, aw , ar Lighting power density (W m2 ) Equipment power density (W m2 ) Air conditioning system EER Interior temperature, Ti (°C) Number of occupantsa per 100 m2 Number of working days per week Working hours
2 200 200 0.30 0.96 3.326
2 40 40 0.30 0.96 3.326
2 25 25 0.30 0.96 3.326
2.115
2.115
2.115
0.4 7.36 2 Split type 6 25 8 5 8:30–16:30
0.4 7.36 2 Split type 6 25 8 5 8:30–16:30
0.4 7.36 2 Split type 6 25 8 5 8:30–16:30
Source: Energy audited reports 1996–1998. a Sensible and latent heat gains per occupant are 73 and 59 W, respectively. Table 6 Breakdown of annual energy consumption for government building models End use
Type 1
Type 2
Type 3
Air conditioning system (kW h) % Share air conditioning Lighting system (kW h) % Share lighting Equipment system (kW h) % Share equipment Total annual energy consumption (kW h) Energy use index (kW h m2 Y1 )
29,835 88.77% 2968 8.83% 806 2.40% 33,609 168
4874 86.59% 594 10.55% 161 2.86% 5629 141
3372 87.72% 371 9.65% 101 2.63% 3844 154
The options are divided into four groups under the headings of building envelope, air conditioning system, lighting system and change in operational schedule. Those options with code numbers preceded by C pertain to commercial buildings and those preceded by G to government buildings. Those marked with asterisks (*) pertain to options suggested by consultants, which may or may not be identical to options simulated (those without asterisks) in our study. Details on each option and cost estimates for some options are given in Table 7. 6.2. Simulation results The options for energy conservation are grouped according to the main causes of energy use in buildings. Results from the simulations are considered in the following.
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Table 7 Energy conservation options Conservation measures Building envelope Improvement of roof insulation
Option no.
Details
CB
GB
CB1
GB1
GB4
Add 25 mm fiber glass to roofs, @ 250 B/roof area (m2 ) Add a fiber glass or polystylene layer, or use ceramic coating Add 20 mm air gap þ9 mm gypsum board to walls, @ 300 B/opaque wall area (m2 ) Add an air gap or a polystylene layer, or use ceramic coating Add a film (SC ¼ 0.39) on to glazing, @ 860 B/glazing area (m2 ) Same as CB3, add a film Change single glazing to double glazing (SC ¼ 0.18), @ 2900 B/glazing area (m2 ) Change to double glazing or add internal blinds or curtains Add overhangs to all windows
GA1 GA1
Increase temperature of supply chilled water from 6.2 to 7.2 °C for all buildings Reduce temperature of cooling water at the outlet of cooling tower from 32.2 to 31.2 °C Replace existing air conditioner (EER ¼ 6) with new air-conditioner (EER ¼ 9.6), @ 15,000 B/RFT
CB1 Improvement of wall insulation
CB2
GB2
CB2 Improvement of glazed windows
CB3
GB3
CB3 CB4 CB4
Air conditioning system Increasing chilled water temperature
CA1
Reducing cooling water temperature
CA2
Other options from consultant reports
CA1
GA2
Increase set-point temperature and/or use electronic thermostats Replace chillers Use desiccant dehumidification system Change the existing constant air volume system to variable air volume system for all buildings Use electronic ballasts so lighting power density changes to 10.96 W m2 for office, 5.08 W m2 for hotel, 8.87 W m2 for hospital, and 14.74 W m2 for department store, @ 450 B each Use low loss magnetic ballasts so lighting power density changes to 11.79 W m2 for office, 5.26 W m2 for hotel, 9.54 W m2 for hospital, and 15.76 W m2 for department store, @ 120 B each Use compact fluorescent lamps so lighting power density changes to 12.87 W m2 for office, 3.41 W m2 for hotel, 10.42 W m2 for hospital, and 16.13 W m2 for department store, @ 200 B each
Reduction of latent load Improvement of air handling system
CA2 CA3 CA4
Lighting system Replacement of existing ballasts with electronic ballasts
CL1 CL1
GL1 GL1
Replacement of existing ballasts with low-loss magnetic ballasts
CL2 CL2
GL2 GL2
Replacement of incandescent lamps by compact fluorescent lamps
CL3 CL3
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Table 7 (continued) Conservation measures
Option no.
Details
CB
GB
Improvement of light delivery
CL4
GL3
Daylighting
CL4
Operational schedule Switching off lights Switching off lights and air-conditioners
CO1 GO1 GO2
Replace existing fixtures with parabolic reflective fixtures Applicable to the office and hospital buildings Switching off lights during 12.00–13.00 h Switching off lights and air-conditioners during 12.00–13.00 Switching off lights and air-conditioners during 12.00–13.00 and only air-conditioners after 15.30
Note: C- - ¼ option for commercial buildings simulated in this paper, C- - ¼ option for commercial buildings proposed by consultants, G- - ¼ option for government buildings simulated in this paper, G- - ¼ option for government buildings proposed by consultants, B ¼ Baht, one unit of Thai currency which equals 1/45 US $.
(a) Building envelope: For the present stock of commercial and government buildings, heat gain through the building envelope is responsible for 30–40% of energy use in a building. The roof and opaque walls of a building offer an attractive opportunity for improvement since retrofitting can usually be performed without much disturbance to people working in the building, and here, the costs are low. Such retrofits are cost effective as can be seen from Table 8. Roof insulation retrofit is slightly more attractive than that for the walls in terms of cost effectiveness. Addition of an optical film to reduce the net heat gain through single glazing is also attractive, especially for older buildings where clear glazing is used. Application of a film to glazing is simple, and the results in Table 9 shows that it is cost effective. The use of double glazing appears to be less attractive with longer payback time. For government buildings, use of the external shading device in the form of overhang is a very cost effective option, with a payback time of <3 years. Simple engineering calculations have been used by engineering professionals in evaluating the costs and benefits of options to retrofit the building envelope of a building. Consultants and engineering professionals have not developed a reliable and accepted method for evaluation of such retrofit options when complex envelope composition is proposed. It is observed that no envelope retrofit for the sake of energy conservation has been undertaken by commercial buildings. For government buildings, the IA mostly avoided making affirmative proposals for envelope retrofit. Use of a ceramic coating (option CB1 in Table 7) is considered by the authors to be equivalent to the use of a coat of white paint (the effect of which is already taken into account in the OTTV formulation). We also have reservations on the use of internal blinds and curtains. Consequently, these two options are not considered in this paper. For most buildings, a combined envelope retrofitting, involving the roof, wall and glazing, offers even more attraction of lower cost and flexibility in retrofit design. In some cases, where glazed areas are excessive, retrofit design that thermally reduces the effective glazed areas could be implemented to improve thermal performance of the envelope even further. Table 10 illustrates the results of simulations for the case of combined retrofit of roof, wall and glazing. Substantial savings can be achieved.
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Table 8 Energy savings from roof and wall insulation Building
Options CB1 and GB1 Peak (%)
CL (%)
Commercial buildings Office 1.4 1.53 Hotel 0.74 1.46 Hospital 1.33 1.98 Depart- 0.99 1.93 ment store Government buildings Type 1 – 11 Type 2 – 14.5 Type 3 – 13
Options CB1 þ CB2=GB1 þ GB2
Options CB2 and GB2
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%) EC (%) PB (Y)
1.15 1.80 2.38 1.57
8.2 4.1 3.9 7.9
4.27 5.57 3.18 0.86
5.05 6.77 2.85 1.06
3.65 6.3 3.48 0.95
8.5 4.7 7.1 11.3
5.63 6.34 4.98 2.17
6.59 8.51 5.45 2.25
4.8 8.22 6.11 2.67
8.5 4.5 5.6 8.7
11.9 14.9 12.5
6.7 6.5 7
– – –
6.14 5.46 3.22
5.3 5.22 3.88
10.2 7.7 15.2
– – –
17.1 20.3 15.9
17.5 19.7 15.7
7.7 6.9 9.3
Note: Peak ¼ reduction in peak power demand, CL ¼ reduction in load sensed by cooling coil, EC ¼ reduction in electric energy consumption, PB ¼ payback time, years, based on the given cost and worth of energy saving calculated at 1.85 B/kW h, B ¼ Baht, one unit of Thai currency which equals 1/45 US $. The above description applies also to Tables 9–17. Table 9 Energy savings from adding a film, double glazing and overhang Building Options CB3 and GB3 Peak (%)
CL (%)
Commercial buildings Office 7.79 10.7 Hotel 2.8 3.59 Hospi3.66 4.28 tal Depart- 3.45 5.11 ment store Government buildings Type 1 – 17 Type 2 – 7.7 Type 3 – 18.1
Option CB4
Option GB4
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
7.12 3.23 4.14
9.8 5.4 7
14 4.94 6.74
19.7 6.3 7.85
13.1 5.71 7.58
18 10.3 12.9
– – –
– – –
– – –
– – –
4.07
4.6
4.74
7.05
5.55
11.4
–
–
–
–
14.3 6.7 16.3
4.7 7.4 4.4
– – –
– – –
– – –
– – –
– – –
8.57 2.36 11.1
7.16 2.72 11.9
4 7.9 2.6
(b) Air conditioning system: Air conditioning accounts for the major portion of energy use for an air conditioned building. For commercial buildings, setting the temperature of the supply chilled water to a higher value and that of the condenser water from the cooling tower to a lower value offers energy saving benefits without cost, as can be seen from the results in Table 11. Generally, these temperatures have fixed set points, calculated to satisfy the design peak cooling load. The peak cooling condition rarely occurs, and the setting forces the chillers to operate in lower efficiency regimes. The
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Table 10 Energy savings from integrated roof–wall glazing retrofit Building
Options CB1 þ CB2 þ CB3 Peak (%)
Commercial buildings Office 13.2 Hotel 9.03 Hospital 9.14 Department 6.84 store Government buildings Type 1 – Type 2 – Type 3 –
Options GB1 þ GB2 þ GB4
CL (%)
EC (%)
PB (Y)
Peak (%) CL (%)
EC (%)
PB (Y)
17.5 12.1 10.4 9.63
12 11.3 10.6 7.8
9.2 4.8 6 5.4
– – – –
– – – –
– – – –
– – – –
– – –
– – –
– – –
– – –
24.8 22.1 26.3
24.2 22.4 26.6
6.8 7 6.7
Table 11 Energy savings from modifying the chilled water system operating strategies Building
Office Hotel Hospital Department store
Option CA1
Options CA1 þ CA2
Option CA2
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
1.6 1.63 1.45 1.37
– – – –
1.32 1.74 1.24 1.25
N/A N/A N/A N/A
1.16 1.2 1.08 1.01
– – – –
0.9 1.15 0.8 0.82
N/A N/A N/A N/A
2.67 2.77 2.45 2.31
– – – –
2.16 2.8 1.98 2.05
N/A N/A N/A N/A
most attractive option is desiccant dehumidification of ventilation air. In the humid climate of Thailand, latent load constitutes 35% of the total cooling load, and desiccant dehumidification can be a healthy and effective option [11]. Savings from this option range from 9.5% to 17% for the four different commercial buildings, as shown in Table 12. These savings are substantial. However, the cost figure for this option is not available. The use of a VAV air handling system has often been suggested, but the results in Table 11 indicate that this option is not effective. Another option suggested in the energy audit reports is the replacement of chillers by more efficient ones (option CA2 in Table 7). Such a drastic change was not simulated. Increasing the set point temperature of the air in the space is another common suggestion. This was not simulated also. For government buildings, the only practical option suggested by the IA was the replacement of air conditioners. Replacement of the air conditioners with values of EER of 6 (COP 1.76), as given in the energy audit report, with new ones with EER of 9.6 (COP 2.81) saves 31–32% of energy use in the air conditioned space with payback periods from 7.5 to 10 years. This is attractive only for replacement of old and worn out units. The size of savings obtained from combined envelope retrofit and replacement of air conditioner for government buildings is shown in Table 13. A common option identified in reports of commercial and government buildings is the use of an electronic thermostat, that would help narrow the temperature dead band (the difference between the turn-off and turn-on temperatures). We consider that this option is to improve comfort for the occupants, but it is unlikely to affect the cooling energy.
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Table 12 Energy savings from use of desiccant dehumidification, use of VAV system and replacement of small air-conditioner Building
Option CA3
Option CA4
Option GA1
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Commercial buildings Office 14.7 Hotel 15.6 Hospital 10.1 Department 10.8 store
18.8 16.4 8.55 13.8
13.7 17.1 11.6 11.1
N/A N/A N/A N/A
1.46 0.03 0.03 0.02
– – – –
9.54 0.04 0.03 0.03
N/A N/A N/A N/A
– – – –
– – – –
– – – –
– – – –
– – –
– – –
– – –
– – –
– – –
– – –
– – –
– – –
– – –
32.2 31.4 31.8
7.5 9.2 10
Government buildings Type 1 – Type 2 – Type 3 –
Table 13 Energy savings from envelope retrofit and replacement of air-conditioners in government buildings Building Type 1 Type 2 Type 3
Options GB1 þ GB2 þ GB4 þ GA1 Peak (%)
CL (%)
EC (%)
PB (Y)
– – –
24.8 22.1 26.3
47.5 45.7 48.7
7.3 8.4 8.5
A common problem in air conditioning is air leakage. Energy used due to air conditioning of ventilation air has been calculated at 100 kW h per person per year (for a ventilation rate of 5 l/s of fresh air per person). The rate of air leakage is expected to be much higher than the required ventilation rate, and such would result in very substantial energy loss, particularly for government buildings. Unfortunately, this problem has not received much attention and has not been mentioned in any of the audit reports. The problem would be reduced if air leakage is also addressed as part of retrofitting the building envelope. (c) Lighting system: For the office, hospital, department store and government buildings, replacement of standard magnetic ballasts (loss of 11 W) by electronic ballasts and low loss ballasts has been suggested in the energy audit reports. In government buildings, the IA replaced most standard ballasts by electronic ballasts. The results shown in Table 14 suggest that the use of low loss magnetic ballast is cost effective, but the electronic ballast is less attractive, both for commercial buildings and government buildings. Replacement of incandescent lamps by compact fluorescent lamps for hotels, hospitals and department stores is very attractive as can be inferred from the results in the table. Natural daylight has been used in traditional government and school buildings. When air conditioning is applied in a space, only electric lighting is used. The results in Table 15 show that substantial savings for offices and hospitals can be achieved if daylighting is used. However, such application implies that dimmable ballasts are used. The cost of dimmable ballasts for fluorescent lamps is too high at present.
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Table 14 Energy savings from use of electronic ballast, use of low-loss magnetic ballast, and use of compact fluorescent lamp Building
Options CL1 and GL1
Options CL2 and GL2
Options CL3
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Commercial buildings Office 4.69 Hotel 2.29 Hospital 4.98 Department 3.23 store
2.4 0.89 1.24 1.15
5.12 1.75 4.95 3.81
8 4.9 7.5 6
2.93 1.37 3.11 2.09
1.5 0.53 0.74 0.74
3.2 1.04 3.07 2.46
3.4 2.2 3.2 2.5
0.47 9.4 0.65 1.58
0.24 3.62 0.15 0.56
0.51 7.15 0.65 1.86
2.2 0.6 1.5 0.7
0.77 0.96 0.86
2.08 2.47 2.26
11.1 10.5 11.2
– – –
0.46 0.58 0.51
1.25 1.49 1.35
4.9 4.6 5
– – –
– – –
– – –
– – –
Government buildings Type 1 – Type 2 – Type 3 –
Table 15 Energy savings from daylighting Building
Option CL4
Office Hospital
25.6 12.4
Peak (%)
CL (%)
EC (%)
PB (Y)
–
26.2 11
N/A N/A
For government buildings, the IA replaced existing fixtures for fluorescent lamps by fixtures with parabolic and reflective surfaces. We do not consider this option cost effective and did not attempt to simulate this option. (d) Change in operational schedule: In some office and some government buildings, it has been observed that turning off air conditioning and switching off lighting in offices during lunch time (12:00–13:00 h) can save significant amounts of energy. The results in Table 16 show that switching off lights and air conditioners during the lunch hour and one hour prior to the end of office hours can save energy, up to 24%, for government buildings. For office buildings, the simulation results confirm savings from switching off electric lighting during the lunch hour. Such options offer savings without incurring cost. (e) Integrated retrofit: In many situations, the individual retrofit option might not afford sufficient savings to justify the cost of that option, but combining the options amalgamates the savings and lowers the overall cost. This would improve the cost effectiveness of integrated retrofit programs over and above those of individual options. A lighting retrofit reduces cooling load as well as directly reducing electricity use. An envelope retrofit reduces cooling load and can lead to reduction of air leakage. With the reduced cooling load from envelope retrofit and improvement in lighting efficiency, the size of a replacement air conditioner can be smaller. Table 17 shows the results of savings and payback times for combining options in both commercial and government buildings. Exceptional success was achieved in a number of government buildings where, in each case, the management of the office played a leading role in instituting an energy conservation
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Table 16 Energy savings from change in operational schedule Building
Option CO1 Peak (%)
Option GO1
CL (%)
Option GO2
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Commercial buildings Office 0.21 –
0.82
N/A
–
–
–
–
–
–
–
–
Government buildings Type 1 – – Type 2 – – Type 3 – –
– – –
– – –
– – –
– – –
9.22 10 10.1
N/A N/A N/A
– – –
– – –
21.7 23.5 23.7
N/A N/A N/A
Table 17 Total energy savings from integrated options Building
Options CB1 þ CB2 þ CB3 þ CA1 þ CA2 þ CL1 þ CL3 þ CO1
Options GB1 þ GB2 þ GB4 þ GA1 þ GO2
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Commercial Office Hotel Hospital Department store
buildings 20.4 22.74 17.06 14.66
20.6 16.80 12.49 13.03
20.33 22.58 18.15 16.13
7.5 3 5.6 4.1
– – – –
– – – –
– – – –
– – – –
Government Type 1 Type 2 Type 3
buildings – – –
– – –
– – –
– – –
– – –
24.83 22.04 26.31
57.87 56.83 59.34
6 6.7 8
committee, which drew support from all occupants of the building in monitoring and controlling energy use. An inherently energy efficient building offers a potential for efficiency, but the successful cases demonstrated that concerted effort by the occupants is needed to achieve the promise.
7. Discussion and conclusion The ECP Act sets a clear and broad objective on energy conservation and creates the ECP Fund with an effective mechanism for replenishment. The ECP Fund Committee, as created by the ECP Act to administer the ECP Fund, performs its dual role of setting regulations for funding and funding approval and setting energy conservation policy. This dual role is passed down to each subcommittee it appoints. The main objective and requirements, as set out in the ministerial regulations or by-laws on energy conservation for designated buildings, seem to us to be clear. The assignment of the DEDP, as IA for the designated commercial building program, and the small government
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building program, is clear and appropriate. However, both programs have not been perceived to have achieved the expected potentials. Although 6 years have passed from the commencement of both programs, no report of retrofit action has been received from the designated commercial building program. An evaluation of the small government building program, completed recently, rated the success of the program at 40% and that actual savings at 46% of the predictions amounted to an internal rate of return less than the requirement of 9% set for the program. We would like to present our perception of the impediment to the success of the programs by an examination first at the technical level and then offer some views on possible remedies. First, the DEDP and the professional community have spent disproportionate attention to individual physical items of equipment. An efficient building has been observed, as perceived by the DEDP and consultants, to be synonymous with efficient air conditioning equipment, efficient lamps, efficient ballast etc. The two programs of the DEDP have not included a component to educate building management and users on the significance of their contribution to the effort. Once new equipment was installed, the management of the building was left, by each IA, to themselves. The benefit of the whole building approach as demonstrated in Section 6.2(e) has also been overlooked. Second, the DEDP did not actively solicit support from the academic and professional community to assist in the technical development. The cost and benefit of each technical option have been assessed using simple engineering calculations. No clear procedure has been developed and adopted for quantification of the benefits from retrofitting the complex components of a building envelope. Hence, envelope retrofit tends to be overlooked. Exaggerated benefits are accorded to some retrofit items proposed by consultants or the IA and approved by the DEDP, such as ceramic coatings and use of electronic thermostats. Embracing such conceptions erodes the credibility of the consultants, the professional engineering community and the DEDP. Adversely, some potentially highly beneficial technologies, such as desiccant dehumidification and alternative low energy cooling systems, may not receive support. Third, the dual role of the ECP Funds Subcommittee in setting policy and approving funds may obscure its own vision on the status and results of programs it supports. A separate body to develop strategies and plans for energy conservation would be envisaged to be able to devote itself more fully to develop better plans. The ECP Fund Subcommittee should also appoint an independent body or group to review each program rigorously and project its support on a more regular basis. In conclusion, the ECP Act has enabled Thailand to initiate significant and substantial activities in energy conservation. However, more experiences remain to be gained.
References [1] Energy and Industry Department, Energy Indicators of Developing Member Countries of Asian Development Bank. Manila: ADB; 1992. [2] Chirarattananon Surapong, Limmechokchai Bundit. A new building efficiency law in Thailand: Impact on new buildings. Energy 1994;19(2):269–78. [3] Chirarattananon Surapong, Rakwamsuk Pattana, Kaewkiew Jinda. A proposed building performance standard for Thailand: An introduction and a preliminary assessment. In: Proceedings of the ASHRAE Far East Conference on air-conditioning in humid climate, Kuala Lumpur, November 1989.
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[4] Coordinating Office for Energy Conservation, Department of Energy Development and Promotion. Energy audit reports of designated commercial buildings and of small government buildings during 1995–2001, DEDP, Ministry of Science Technology and Environment, Thailand. [5] ASHRAE handbook of fundamentals. GA: ASHRAE; 2001, chapter 8. [6] Bida M, Krieder JF. Monthly averaged cooling load calculations residential and small commercial buildings. J Solar Energy Engng 1987;109:311–20. [7] Parker DS, Fairey PW, Mcllvaine JER. Energy efficient office building design for Florida’s hot and humid climate. ASHRAE J 1997;39(4):49–58. [8] Kim K-S, Yoon J-H, Lee E-J, Choi S, Krarti M. Building energy performance simulations to evaluate energy conservation measures for commercial building in Korea. Solar Engng, ASME 1998:19–24. [9] Lam JC. Climatic influences on the energy performance of air-conditioned buildings. Energy Convers Mgmt 1999;40:39–49. [10] Chou SK, Chang WL. Large building cooling load and energy use estimation. Int J Energy Res 1997;21:169–83. [11] Techajunta S. A study of solar regenerated desiccant air-conditioning in tropical humid climate, a Doctor of Engineering thesis, Asian Institute of Technology, 1999.
A technical review of energy conservation programs for commercial and government buildings in Thailand Surapong Chirarattananon *, Juntakan Taweekun Energy Program, Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathumthani 12120, Thailand Received 15 October 2001; accepted 20 March 2002
Abstract This paper examines the requirements for designated buildings and the mechanisms for implementation of energy conservation programs in accordance with the Energy Conservation Promotion Act of Thailand. It then reviews the details of energy audits and implementation of energy conservation of designated commercial buildings and small government buildings. Through use of the DOE-2 simulation program and reference building models developed from energy audit information, it is shown that whole building retrofit is more cost effective than adopting individual options. It also points out that mobilizing involvement of the occupants of a building is a necessary and integral part of a successful energy conservation program. The paper also suggests means to overcome the present impediments to successful implementation of the programs. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Energy conservation; Energy simulation; Overall thermal transfer value; Energy performance of buildings; Energy audit
1. Introduction The elasticity of energy use to gross domestic product in Thailand, a country in the tropical region of Southeast Asia, averaged 1.12 for the earlier two decades despite past energy conservation policies adopted by the state [1]. In commercial buildings, air conditioning has reached saturation. There has been an increasing use of curtained wall design for large commercial
*
Corresponding author. Tel.: +66-2-524-5437; fax: +66-2-524-5439/6589. E-mail address: [email protected] (S. Chirarattananon).
0196-8904/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 1 9 6 - 8 9 0 4 ( 0 2 ) 0 0 0 8 2 - 1
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buildings. These buildings use glazings of low shading coefficient and low visible transmittance so that very little daylight can enter, and each building relies heavily on electric lighting. In earlier times, air conditioning was not allowed, but by the early 1990s, air conditioning had penetrated all government buildings. A few rooms or a few enclosed spaces in a typical government building would be conditioned by small stand alone, split-type (each with a separate condensing unit and a separate fan coil unit) air conditioners. In 1992, the Thai government promulgated an Energy Conservation Promotion Act (ECP Act) to promote energy conservation and development of renewable energy in a comprehensive way. The priority segments for energy conservation included large commercial buildings and government buildings. A fund for promotion of energy conservation (ECP Fund) was also formed under the ECP Act. The fund receives US$30–70 millions (M) per year, mainly by collection of a levy on domestic consumption of oil. The ECP Fund has been used to engage consulting firms to conduct energy audits on over 1000 designated commercial buildings. It has also been used to support energy audits and retrofits of 573 small government buildings. The options for improvements and retrofitting of these small government buildings are identified by the energy auditors and generally approved by the relevant authorities. In calculating the energy savings from an option, approved engineering calculation procedures are used. These straightforward calculations are simple but neglect the interactive effects of different measures. This paper briefly describes the provisions and requirements of the ECP Act relevant to designated commercial buildings. It then outlines the organization and management of programs for energy conservation in designated commercial buildings and in the small government buildings of relevant agencies. The paper examines the options for energy conservation in these buildings as suggested by the consultants and agencies and, additionally, those deemed appropriate by the authors for application in tropical climates. It then utilizes a well known energy simulation program to calculate the size and cost of the energy savings of each of the reference options, as well as those additional options. The results show that many additional cost effective options for energy conservation should be adopted. Some of these options may involve technologies unfamiliar to local professional societies. The results find the whole building approach to be more cost effective than adopting individual retrofit options. The study also examines successful cases and suggests that building occupants must be involved for a program to achieve real sustained success. The paper also discusses some adverse conditions and impediments to furthering the success of the energy conservation efforts in Thailand.
2. Requirements and the implementation of the ECP Act As has been reported earlier, one objective of the ECP Act was to improve the energy efficiency in buildings [2]. A royal decree was issued in 1995 to designate buildings for compliance with the mandatory requirements of the Act as being those whose electric power and/or equivalent energy demand exceed 1 MW. In the same year, the detailed requirements on designated buildings were announced as a set of ministerial regulations or by-laws of the ECP Act.
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2.1. Requirements on designated buildings The average lighting power for an office, a hospital or a hotel building must not exceed 18 W m2 . For a department store or retail store building the amount is 23 W m2 . For a new building, the overall thermal transfer value (OTTV) of the walls must not exceed 45 W m2 , and for an existing building, the value is 55 W m2 . For the roof, the value is 25 W m2 . There is a detailed set of requirements on the rated power per unit capacity (kW/RFT, refrigeration ton) of air cooled and water cooled chillers of different sizes. The OTTV is devised as a measure of the thermal performance of the building envelope of air conditioned buildings. A set of calculation procedures and property values are given for evaluating the OTTV of a building as a part of the by-laws of the ECP Act. The OTTV formulation has been validated earlier [3]. 2.2. Implementation of the ECP Act A Committee for administering the ECP Fund (ECP Fund Committee), chaired by the prime minister or a deputy prime minister, has been set up in accordance with the ECP Act. The committee appoints three subcommittees. One subcommittee is tasked to assist in the allocation and award of funding for works related to the mandatory requirements of the ECP Act. The other subcommittees oversee funding for the rest of the works under the ECP Act. These include research and development, demonstration, promotion of renewable energy, public relations and human resource development. Each designated building is required by law to engage a consultant to conduct the energy audit, set up the plan and target for energy conservation and to implement the plan to satisfy the requirements of the ECP Act and its by-laws. Funding is available to cover most of the costs of the consultancy, with a total amount available up to 0.6 MB (equivalent to about US $15,000) for each designated building. Funding to cover parts of the cost of retrofit is also available under some conditions. By the early part of 2001, almost all of the 1000 designated buildings have been audited [4] but none has been reported retrofitted for energy conservation under this scheme. The Department of Energy Development and Promotion (DEDP), a government department within the Ministry of Science Technology and Environment, is entrusted by the ECP Act to conduct works related to the mandatory requirements. The energy audit report and plan for improvement for each designated building must be approved by the DEDP for funding to be disbursed. Large government buildings are also subject to the requirements of the ECP Act, but funding can be extended to retrofitting if the resultant internal rate of return of savings exceeds 9% for each building. However, no time frame is set for the management of these government buildings to comply with the requirements of the ECP Act, so the status of the development has not been assessed. A project for retrofitting small government buildings (those whose power demand exceed 100 kW but less than 1 MW) was also created in 1995. By April 2001, 573 of such buildings have been completely audited and retrofitted at a total cost of US $40 M. The objective and funding conditions for retrofitting these buildings are the same as those for large government buildings, but the works were performed by agencies of state universities with close supervision by the DEDP [4].
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3. Energy audits and implementation of energy conservation for designated commercial buildings and small government buildings For the designated commercial buildings, the premise is that the direct beneficiaries of energy conservation are the building management, and so, they should be responsible primarily for the costs of retrofits. For government buildings, it is perceived that the public is the eventual beneficiary, so the state can invest in retrofitting government buildings. 3.1. Designated commercial buildings A private consultant would be chosen by the management of a building from a list of registered consulting companies given by the DEDP. The consultant would typically conduct a field (onsite) energy audit of the building. The items of information a consultant files in the energy audit report are shown in Table 1. From the details obtained on the building dimensions, orientation and construction, a consultant would calculate the wall OTTV and the roof OTTV of a given building. The monthly electric energy (kW h), peak power consumption (kW) in peak, partial peak and off-peak periods and value of power factor are obtainable from the electric bill of a building. In the course of an Table 1 Information items in the energy audit report on a commercial building Item Type, location, age
Detail
Office, hotel, etc.; city and region; the year construction completed Shape, dimension Photographs and diagrams Orientation North, south etc., azimuth of each facade Construction Composition and area of each opaque wall, thermal properties of wall materials, conductivity, shading devices, etc. Roof details Glazing type and area, shading coefficient, thermal properties Area usage Size of air-conditioned area, unconditioned area, car park Identification of areas classified according to functions: office, guest room meeting room, etc. Energy system and use Electricity: power and energy in major feeders, transformer losses, light and plug load, air-conditioning system Boiler: gas or oil and hot water use Air-conditioning Total design capacity, ratings of components System and effects Measured indices: COP of chillers, system COP, temperature and relative humidity in each zone, air enthalpy Lighting system and effects Lighting devices: type and rating in each area, illuminance in an area Equipment Central service equipment (e.g. lifts) Equipment in air-conditioned areas, etc.
Unit (when applicable) Y m degree m, W m1 K1
m2
kW, kW h
l, MJ RFT, m2 /RFT, kW, °C, %, kJ kg1 W, W m2 , lux kW kW, W m2
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audit, a consultant usually carries a set of portable equipment for measurement of electric power, illuminance, relative humidity of air, temperature of air, temperature of water and surfaces of chilled water pipes. The electric power taken by the air conditioning system and the total power of the building are measured as instantaneous values during the time of an audit. The total lighting power is calculated by summing the rated power of all lighting equipment and lamps. The electric power of plug loads and other equipment are calculated by subtracting from the measured value of the building load the measured air conditioning load and the calculated lighting load. The proportionate shares of electric power among the three major categories of loads are then used subsequently to calculate the shares of the monthly and annual cooling and lighting energy of the building. The coefficient of performance (COP) of a water chiller can be obtained from the value of the refrigeration effect, calculated from the known chilled water flow and the measured temperatures of the return and supply chilled water and the measured power taken by the chiller. For a direct expansion air conditioning unit, a similar method can be employed to obtain its COP. Some energy use and performance indices and the ranges of values obtained from energy audits are as shown in Table 2. The audit results confirm the results from earlier studies [2] that typically air conditioning is responsible for 60% of electricity consumption in a commercial building. Heat gain through the building envelope contributes up to 60% of the total cooling load. Electric lighting contributes 20% of the electricity consumption and also contributes up to 20% to the cooling load. Each audit report identifies options for energy conservation and calculates the costs and benefits using rated values and engineering calculations for each option. No interactive effects, such as the corresponding reduction in cooling load to the air conditioning system from reduced electricity use of more efficient equipment is taken into account. Moreover, the calculated reductions in electricity use from different options are simply summed. For example, the use of optical film on glazed windows is estimated to save 40 units of energy. (This is expected to reduce the heat gain and the corresponding cooling energy from the base situation.) Replacing the Table 2 Ranges of values of some energy use and performance indices Item
Office
Hotel
Hospital
Department store
% of area air-conditioned Wall OTTV (W m2 ) Roof OTTV (W m2 ) Energy index (kW h m2 Y1 )
43–100 32–105 3–67 97–350
65–84 33–90 18–45 141–580
36–70 44–74 10–45 104–775
82–100 32–84 60–62 170–480
Air-conditioned area Design coverage (m2 /RFT) Energy index (kW h m2 Y1 ) Chiller COP System COP
10–26 57–160 1.8–5.3 1.5–2.9
9–44 81–112 3.3–4.9 1.5–2.2
7–32 65–207 2.6–4.8 1.7–2.9
11–24 134–210 3.8–5.3 2.3–2.6
Lighting, office space Illuminance (lux) Power density (W m2 ) Energy index (kW h m2 Y1 )
200–520 5–33 19–53
116–218 3–17 28–63
200–360 4–26 19–53
320–440 7–33 17–99
Note: Areas of car park are excluded in calculation of energy use indices.
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existing air conditioner with a COP of 1.75 by another one with COP of 3.0 is estimated to save 40 units from the base case. An energy audit would report a total saving of 80 units. The first option would already reduce the cooling load below the base value, and the following option would save from the new reduced base. The options for energy efficiency improvement suggested in the audits are listed in Table 7 of Section 6. Each energy audit report must be approved by the DEDP before funds can be disbursed. The format of the report, as well as the options recommended, must conform to a standard. Energy conservation options outside of the standard list are not encouraged. Individual schedules and the diversities of use of space, equipment and lighting are not recorded in the audits. 3.2. Small government building project The main objective is to reduce energy use in government buildings and to set examples of good practice on prudent and efficient use of energy to the public. State universities have created extensions or community service units to enhance their services to the public. A number of these units from different universities were appointed as implementing agencies (IA) by the DEDP, each to conduct energy audits and recommend retrofit options on a group of buildings chosen by the DEDP. The same IA would be assigned to supervise retrofitting the same group of buildings for the options approved by the DEDP and the ECP Fund Committee. The format and information items in each report are similar to those filed by the consulting companies (Table 1). However, since the buildings are smaller, all use stand alone, split-type air conditioners. Each report also produces values of the energy use indices. However, values of the energy efficiency ratio (EER) of air conditioners are reported. An EER is the ratio of cooling in the unit of BTU/h produced per unit of electric power (W) taken. Measurements of the speed and the condition of moist air input to and output from an air conditioner are required to obtain the amount of cooling it produces. The typical value of EER obtained for existing air conditioners from the reports is 6. This corresponds to a COP of 1.76. Government buildings are generally old and were not designed for air conditioning. Illuminance levels were also observed to be low. Recommended retrofit options exclude those involving the building envelope, mainly because the areas involved in each building were considered too small and the retrofitting jobs too small to attract building contractors. Most accepted options include replacing air conditioners, installing electronic thermostats (in place of electromagnetic thermostats commonly used earlier), replacing existing fluorescent fixtures by reflective parabolic fixtures, replacing existing magnetic ballasts by electronic ballasts and replacing standard fluorescent lamps (each rated at 36 W and producing 2700 lm) by efficient lamps (each rated at 36 W and producing 3350 lm). So the recommended and approved options include only replacement of air conditioners and luminaires.
4. Methodologies for calculation of energy use in buildings In earlier times, the methods employed to predict energy use in buildings were based on the use of heating-degree hours or cooling-degree hours and steady state calculations [5]. Use of a solar utilizability factor and variable base temperatures and binning of weather data improve the
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prediction of heating and cooling loads and energy use [5,6], but all these earlier methods use the steady state concept and are applicable with sufficient accuracy for buildings with single zone and a regular schedule of use. Large buildings comprise multiple zones, each with separate schedules of occupancy, lighting and equipment use. The interactive effects of different equipment use and the effect on cooling load in air conditioned buildings, as well as the storage effects of the masses of building components must be taken into account. Added to the complexity is the dependence of the performance of the air conditioning system on how the system is operated. Use of sophisticated computer programs is necessary to achieve an acceptable degree of accuracy. A well known building energy simulation program developed under support from the Department of Energy of USA, called DOE-2, was used in this work to simulate the energy use in the designated commercial buildings and in small government buildings. Version 2.1E of the program was used. This program is up-to-date, unbiased, well documented and requires a detailed description of the building construction and schedules of use of equipment, occupancy and space in each individual zone. It also requires hourby-hour weather data. For this study, the weather data of Bangkok was used. Parker et al. used DOE-2 for simulation analysis of different features to improve energy efficiency in the design of an office in the Florida Solar Energy Center under the hot and humid climate of Florida [7]. The simulation results were partially verified one year after completion of the construction of the building. Kim et al. used DOE-2 simulation to evaluate the relative performance of constant-air-volume and variable-air-volume (VAV) air handling systems, an ice storage control strategy and a number of other options for an office building in Seoul, Korea [8]. In Hong Kong, Lam utilized DOE-2 to calculate and compare monthly and annual cooling loads and energy use of a generic building using weather data of different years [9]. Chou and Chang utilized DOE-2 to develop simplified relationships for predicting annual energy use for a number of buildings in Singapore [10]. 4.1. Simulation methodology In order to use DOE-2, a reference building model representing each identified building group is developed based on energy audit data. Baseline information on building characteristics, equipment use and operational schedules, together with weather data, were used with each building model to run DOE-2 to obtain reference cooling load and energy use information. Options for improving energy efficiency were then applied, and DOE-2 was again run to produce comparative outputs for use in comparing and evaluating the cost effectiveness of different options.
5. Reference building models and energy consumption The two groups of buildings require two different sets of reference building models. 5.1. Reference models for designated commercial buildings The ECP Act recognizes four types of commercial buildings. Information obtained from a large number of energy audit reports on commercial buildings was used to construct four reference
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Fig. 1. The shapes of four reference building models: (a) office, (b) hotel, (c) hospital and (d) department store.
building models, each for one type of commercial building. The shapes of the four models are shown in Fig. 1. All are rectangular with the smaller facades facing east and west. The opaque walls of these buildings typically comprise cement plastered brick work. Single glazing is mostly used. Centralized air conditioning systems are used with water cooled centrifugal chillers. Fluorescent lighting is employed in the office space, in corridors and in most spaces of most buildings, except a hotel. Incandescent lamps are used in guest rooms, function rooms and other places in a hotel. The levels of illuminance in hotels are lower than those in other commercial buildings. Table 3 lists the details of the models relevant to the present work. Each model incorporates the most common features of the building type. The length and width of each building are comparable, so that the area of each floor is large and the ratio of total wall area to total floor area of each building is relatively small. As is common, the ratio of window area to total wall area for the hotel is small, while those for other building types are larger. 5.2. Energy use of reference models for designated commercial buildings Summarized annual energy use of the reference models obtained from DOE-2 simulation is shown in Table 4. The percentage share of energy use due to air conditioning, lighting etc. and the value of the energy use index for each building type match with those from the audit reports. 5.3. Reference models for small government buildings Government buildings are rectangular and commonly comprise two stories. The opaque wall is typically constructed from cement plastered brickwork. Single clear glazing is used. Normal operating time is between 8:30 and 16:30 h during weekdays, and the buildings are closed during weekends and holidays. Lighting and equipment power densities are rather low. Most government buildings are old and were originally designed for natural ventilation, but air conditioners have
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Table 3 Details of commercial building models Item
Office
Hotel
Hospital
Department store
Number of stories Total area of opaque walls (m2 ) Total area of glazings (m2 ) Total area of roof (m2 ) Total area of floors (m2 ) Ratio of wall area to floor area Ratio of window area to wall area, WWR Shading coefficient of glazing, SC Overall coefficient of heat transfer for wall, Uw (W m2 K1 ) Overall coefficient of heat transfer for roof, Ur (W m2 K1 ) Solar absorptance of wall and roof surfaces, aw , ar Annual average OTTV (W m2 ) Air handling system Lighting power density (W m2 ) Equipment power density (W m2 ) Interior temperature, Ti (°C) Number of occupantsb per 100 m2 Number of working days per week Working hours Number of zones in DOE-2 simulation Zone 1 Zone 2 (core or podium) Zone 3
12 3883 3051 1421 12,567 0.55 0.44 0.64 2.957
8 3585 734 1080 11,448 0.37 0.17 0.64 2.957
8 3803 1553 1728 17,280 0.30 0.29 0.64 2.957
3 1972 1208 2760 8280 0.38 0.38 0.96 2.957
1.845
1.845
1.845
1.845
0.4 62.32 CAVa 13.18 12.88 25 7 5 8:00–17:00 3 Floor 1 Core Floors 2–12
0.4 56.38 CAV 5.56 2.3 25 20 7 0:00–24:00 3 Floor 1 Floors 2–3 Floors 4–8
0.4 52.78 CAV 10.67 3.36 25 10 7 0:00–24:00 3 Floor 1 Floors 2–3 Floors 4–8
0.4 65.48 CAV 17.48 25.05 25 20 7 10:00–21:00 3 Floor 1 Floor 2 Floor 3
Source: energy audit reports of 1997–2001. a CAV ¼ constant air volume system. b Sensible and latent heat gains per occupant used are 73 and 59 W, respectively. Table 4 Breakdown of annual energy consumption for commercial building models End-use
Office
Hotel
Hospital
Department store
Air conditioning system (kW h) % Share air conditioning Lighting system (kW h) % Share lighting Equipment system (kW h) % Share equipment Total annual energy consumption (kW h) Total annual cooling load (kW h) Energy use index (kW h m2 Y1 )
1,345,612 66.41% 433,918 21.41% 246,807 12.18% 2,026,337 3,005,204 161
1,702,305 86.94% 193,210 9.87% 62,499 3.19% 1,958,014 3,598,488 171
1,893,502 76.05% 491,777 19.75% 104,530 4.20% 2,489,809 3,230,224 144
1,857,109 62.09% 541,034 18.09% 592,969 19.82% 2,991,112 4,039,274 361
been reportedly installed in some enclosed spaces of each building. The air conditioners used are mostly split-type. Three types of buildings are identified from consideration of the size and
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Fig. 2. Government building models.
location of the main air conditioned space. Type 1 represents state enterprise and ministerial buildings, type 2 represents school buildings and city halls and type 3 represents hospital buildings. The details are shown in Fig. 2 and Table 5. 5.4. Energy use of reference models for small government buildings Summarized annual energy use of the reference models for small government buildings are shown in Table 6. The values of energy use indices pertain to the air conditioned space only. The relative share of energy use in unconditioned spaces is much lower in a government building. Natural daylight is used, and occasionally, a small fan is used in most unconditioned spaces. Computers and other electrical equipment are generally housed in an air conditioned room where electric lighting is invariably used. Our attention in the energy conservation effort will be focussed on air conditioned spaces. 6. Evaluation of options for energy conservation 6.1. Options for energy conservation The costs and benefits of the options for energy conservation are assessed in the energy report submitted by the consultant to the management of each commercial building and in the report submitted by each IA for a government building. The lists of these options are given in Table 7.
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Table 5 Details of government building models Parameter
Type 1
Type 2
Type 3
Number of stories Total area of roof (m2 ) Total area of floor (m2 ) Ratio of window area to wall area, WWR Shading coefficient, SC Overall coefficient of heat transfer for wall, Uw (W m2 K1 ) Overall coefficient of heat transfer for roof, Ur (W m2 K1 ) Solar absorptance of wall and roof surfaces, aw , ar Lighting power density (W m2 ) Equipment power density (W m2 ) Air conditioning system EER Interior temperature, Ti (°C) Number of occupantsa per 100 m2 Number of working days per week Working hours
2 200 200 0.30 0.96 3.326
2 40 40 0.30 0.96 3.326
2 25 25 0.30 0.96 3.326
2.115
2.115
2.115
0.4 7.36 2 Split type 6 25 8 5 8:30–16:30
0.4 7.36 2 Split type 6 25 8 5 8:30–16:30
0.4 7.36 2 Split type 6 25 8 5 8:30–16:30
Source: Energy audited reports 1996–1998. a Sensible and latent heat gains per occupant are 73 and 59 W, respectively. Table 6 Breakdown of annual energy consumption for government building models End use
Type 1
Type 2
Type 3
Air conditioning system (kW h) % Share air conditioning Lighting system (kW h) % Share lighting Equipment system (kW h) % Share equipment Total annual energy consumption (kW h) Energy use index (kW h m2 Y1 )
29,835 88.77% 2968 8.83% 806 2.40% 33,609 168
4874 86.59% 594 10.55% 161 2.86% 5629 141
3372 87.72% 371 9.65% 101 2.63% 3844 154
The options are divided into four groups under the headings of building envelope, air conditioning system, lighting system and change in operational schedule. Those options with code numbers preceded by C pertain to commercial buildings and those preceded by G to government buildings. Those marked with asterisks (*) pertain to options suggested by consultants, which may or may not be identical to options simulated (those without asterisks) in our study. Details on each option and cost estimates for some options are given in Table 7. 6.2. Simulation results The options for energy conservation are grouped according to the main causes of energy use in buildings. Results from the simulations are considered in the following.
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Table 7 Energy conservation options Conservation measures Building envelope Improvement of roof insulation
Option no.
Details
CB
GB
CB1
GB1
GB4
Add 25 mm fiber glass to roofs, @ 250 B/roof area (m2 ) Add a fiber glass or polystylene layer, or use ceramic coating Add 20 mm air gap þ9 mm gypsum board to walls, @ 300 B/opaque wall area (m2 ) Add an air gap or a polystylene layer, or use ceramic coating Add a film (SC ¼ 0.39) on to glazing, @ 860 B/glazing area (m2 ) Same as CB3, add a film Change single glazing to double glazing (SC ¼ 0.18), @ 2900 B/glazing area (m2 ) Change to double glazing or add internal blinds or curtains Add overhangs to all windows
GA1 GA1
Increase temperature of supply chilled water from 6.2 to 7.2 °C for all buildings Reduce temperature of cooling water at the outlet of cooling tower from 32.2 to 31.2 °C Replace existing air conditioner (EER ¼ 6) with new air-conditioner (EER ¼ 9.6), @ 15,000 B/RFT
CB1 Improvement of wall insulation
CB2
GB2
CB2 Improvement of glazed windows
CB3
GB3
CB3 CB4 CB4
Air conditioning system Increasing chilled water temperature
CA1
Reducing cooling water temperature
CA2
Other options from consultant reports
CA1
GA2
Increase set-point temperature and/or use electronic thermostats Replace chillers Use desiccant dehumidification system Change the existing constant air volume system to variable air volume system for all buildings Use electronic ballasts so lighting power density changes to 10.96 W m2 for office, 5.08 W m2 for hotel, 8.87 W m2 for hospital, and 14.74 W m2 for department store, @ 450 B each Use low loss magnetic ballasts so lighting power density changes to 11.79 W m2 for office, 5.26 W m2 for hotel, 9.54 W m2 for hospital, and 15.76 W m2 for department store, @ 120 B each Use compact fluorescent lamps so lighting power density changes to 12.87 W m2 for office, 3.41 W m2 for hotel, 10.42 W m2 for hospital, and 16.13 W m2 for department store, @ 200 B each
Reduction of latent load Improvement of air handling system
CA2 CA3 CA4
Lighting system Replacement of existing ballasts with electronic ballasts
CL1 CL1
GL1 GL1
Replacement of existing ballasts with low-loss magnetic ballasts
CL2 CL2
GL2 GL2
Replacement of incandescent lamps by compact fluorescent lamps
CL3 CL3
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Table 7 (continued) Conservation measures
Option no.
Details
CB
GB
Improvement of light delivery
CL4
GL3
Daylighting
CL4
Operational schedule Switching off lights Switching off lights and air-conditioners
CO1 GO1 GO2
Replace existing fixtures with parabolic reflective fixtures Applicable to the office and hospital buildings Switching off lights during 12.00–13.00 h Switching off lights and air-conditioners during 12.00–13.00 Switching off lights and air-conditioners during 12.00–13.00 and only air-conditioners after 15.30
Note: C- - ¼ option for commercial buildings simulated in this paper, C- - ¼ option for commercial buildings proposed by consultants, G- - ¼ option for government buildings simulated in this paper, G- - ¼ option for government buildings proposed by consultants, B ¼ Baht, one unit of Thai currency which equals 1/45 US $.
(a) Building envelope: For the present stock of commercial and government buildings, heat gain through the building envelope is responsible for 30–40% of energy use in a building. The roof and opaque walls of a building offer an attractive opportunity for improvement since retrofitting can usually be performed without much disturbance to people working in the building, and here, the costs are low. Such retrofits are cost effective as can be seen from Table 8. Roof insulation retrofit is slightly more attractive than that for the walls in terms of cost effectiveness. Addition of an optical film to reduce the net heat gain through single glazing is also attractive, especially for older buildings where clear glazing is used. Application of a film to glazing is simple, and the results in Table 9 shows that it is cost effective. The use of double glazing appears to be less attractive with longer payback time. For government buildings, use of the external shading device in the form of overhang is a very cost effective option, with a payback time of <3 years. Simple engineering calculations have been used by engineering professionals in evaluating the costs and benefits of options to retrofit the building envelope of a building. Consultants and engineering professionals have not developed a reliable and accepted method for evaluation of such retrofit options when complex envelope composition is proposed. It is observed that no envelope retrofit for the sake of energy conservation has been undertaken by commercial buildings. For government buildings, the IA mostly avoided making affirmative proposals for envelope retrofit. Use of a ceramic coating (option CB1 in Table 7) is considered by the authors to be equivalent to the use of a coat of white paint (the effect of which is already taken into account in the OTTV formulation). We also have reservations on the use of internal blinds and curtains. Consequently, these two options are not considered in this paper. For most buildings, a combined envelope retrofitting, involving the roof, wall and glazing, offers even more attraction of lower cost and flexibility in retrofit design. In some cases, where glazed areas are excessive, retrofit design that thermally reduces the effective glazed areas could be implemented to improve thermal performance of the envelope even further. Table 10 illustrates the results of simulations for the case of combined retrofit of roof, wall and glazing. Substantial savings can be achieved.
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Table 8 Energy savings from roof and wall insulation Building
Options CB1 and GB1 Peak (%)
CL (%)
Commercial buildings Office 1.4 1.53 Hotel 0.74 1.46 Hospital 1.33 1.98 Depart- 0.99 1.93 ment store Government buildings Type 1 – 11 Type 2 – 14.5 Type 3 – 13
Options CB1 þ CB2=GB1 þ GB2
Options CB2 and GB2
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%) EC (%) PB (Y)
1.15 1.80 2.38 1.57
8.2 4.1 3.9 7.9
4.27 5.57 3.18 0.86
5.05 6.77 2.85 1.06
3.65 6.3 3.48 0.95
8.5 4.7 7.1 11.3
5.63 6.34 4.98 2.17
6.59 8.51 5.45 2.25
4.8 8.22 6.11 2.67
8.5 4.5 5.6 8.7
11.9 14.9 12.5
6.7 6.5 7
– – –
6.14 5.46 3.22
5.3 5.22 3.88
10.2 7.7 15.2
– – –
17.1 20.3 15.9
17.5 19.7 15.7
7.7 6.9 9.3
Note: Peak ¼ reduction in peak power demand, CL ¼ reduction in load sensed by cooling coil, EC ¼ reduction in electric energy consumption, PB ¼ payback time, years, based on the given cost and worth of energy saving calculated at 1.85 B/kW h, B ¼ Baht, one unit of Thai currency which equals 1/45 US $. The above description applies also to Tables 9–17. Table 9 Energy savings from adding a film, double glazing and overhang Building Options CB3 and GB3 Peak (%)
CL (%)
Commercial buildings Office 7.79 10.7 Hotel 2.8 3.59 Hospi3.66 4.28 tal Depart- 3.45 5.11 ment store Government buildings Type 1 – 17 Type 2 – 7.7 Type 3 – 18.1
Option CB4
Option GB4
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
7.12 3.23 4.14
9.8 5.4 7
14 4.94 6.74
19.7 6.3 7.85
13.1 5.71 7.58
18 10.3 12.9
– – –
– – –
– – –
– – –
4.07
4.6
4.74
7.05
5.55
11.4
–
–
–
–
14.3 6.7 16.3
4.7 7.4 4.4
– – –
– – –
– – –
– – –
– – –
8.57 2.36 11.1
7.16 2.72 11.9
4 7.9 2.6
(b) Air conditioning system: Air conditioning accounts for the major portion of energy use for an air conditioned building. For commercial buildings, setting the temperature of the supply chilled water to a higher value and that of the condenser water from the cooling tower to a lower value offers energy saving benefits without cost, as can be seen from the results in Table 11. Generally, these temperatures have fixed set points, calculated to satisfy the design peak cooling load. The peak cooling condition rarely occurs, and the setting forces the chillers to operate in lower efficiency regimes. The
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Table 10 Energy savings from integrated roof–wall glazing retrofit Building
Options CB1 þ CB2 þ CB3 Peak (%)
Commercial buildings Office 13.2 Hotel 9.03 Hospital 9.14 Department 6.84 store Government buildings Type 1 – Type 2 – Type 3 –
Options GB1 þ GB2 þ GB4
CL (%)
EC (%)
PB (Y)
Peak (%) CL (%)
EC (%)
PB (Y)
17.5 12.1 10.4 9.63
12 11.3 10.6 7.8
9.2 4.8 6 5.4
– – – –
– – – –
– – – –
– – – –
– – –
– – –
– – –
– – –
24.8 22.1 26.3
24.2 22.4 26.6
6.8 7 6.7
Table 11 Energy savings from modifying the chilled water system operating strategies Building
Office Hotel Hospital Department store
Option CA1
Options CA1 þ CA2
Option CA2
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
1.6 1.63 1.45 1.37
– – – –
1.32 1.74 1.24 1.25
N/A N/A N/A N/A
1.16 1.2 1.08 1.01
– – – –
0.9 1.15 0.8 0.82
N/A N/A N/A N/A
2.67 2.77 2.45 2.31
– – – –
2.16 2.8 1.98 2.05
N/A N/A N/A N/A
most attractive option is desiccant dehumidification of ventilation air. In the humid climate of Thailand, latent load constitutes 35% of the total cooling load, and desiccant dehumidification can be a healthy and effective option [11]. Savings from this option range from 9.5% to 17% for the four different commercial buildings, as shown in Table 12. These savings are substantial. However, the cost figure for this option is not available. The use of a VAV air handling system has often been suggested, but the results in Table 11 indicate that this option is not effective. Another option suggested in the energy audit reports is the replacement of chillers by more efficient ones (option CA2 in Table 7). Such a drastic change was not simulated. Increasing the set point temperature of the air in the space is another common suggestion. This was not simulated also. For government buildings, the only practical option suggested by the IA was the replacement of air conditioners. Replacement of the air conditioners with values of EER of 6 (COP 1.76), as given in the energy audit report, with new ones with EER of 9.6 (COP 2.81) saves 31–32% of energy use in the air conditioned space with payback periods from 7.5 to 10 years. This is attractive only for replacement of old and worn out units. The size of savings obtained from combined envelope retrofit and replacement of air conditioner for government buildings is shown in Table 13. A common option identified in reports of commercial and government buildings is the use of an electronic thermostat, that would help narrow the temperature dead band (the difference between the turn-off and turn-on temperatures). We consider that this option is to improve comfort for the occupants, but it is unlikely to affect the cooling energy.
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Table 12 Energy savings from use of desiccant dehumidification, use of VAV system and replacement of small air-conditioner Building
Option CA3
Option CA4
Option GA1
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Commercial buildings Office 14.7 Hotel 15.6 Hospital 10.1 Department 10.8 store
18.8 16.4 8.55 13.8
13.7 17.1 11.6 11.1
N/A N/A N/A N/A
1.46 0.03 0.03 0.02
– – – –
9.54 0.04 0.03 0.03
N/A N/A N/A N/A
– – – –
– – – –
– – – –
– – – –
– – –
– – –
– – –
– – –
– – –
– – –
– – –
– – –
– – –
32.2 31.4 31.8
7.5 9.2 10
Government buildings Type 1 – Type 2 – Type 3 –
Table 13 Energy savings from envelope retrofit and replacement of air-conditioners in government buildings Building Type 1 Type 2 Type 3
Options GB1 þ GB2 þ GB4 þ GA1 Peak (%)
CL (%)
EC (%)
PB (Y)
– – –
24.8 22.1 26.3
47.5 45.7 48.7
7.3 8.4 8.5
A common problem in air conditioning is air leakage. Energy used due to air conditioning of ventilation air has been calculated at 100 kW h per person per year (for a ventilation rate of 5 l/s of fresh air per person). The rate of air leakage is expected to be much higher than the required ventilation rate, and such would result in very substantial energy loss, particularly for government buildings. Unfortunately, this problem has not received much attention and has not been mentioned in any of the audit reports. The problem would be reduced if air leakage is also addressed as part of retrofitting the building envelope. (c) Lighting system: For the office, hospital, department store and government buildings, replacement of standard magnetic ballasts (loss of 11 W) by electronic ballasts and low loss ballasts has been suggested in the energy audit reports. In government buildings, the IA replaced most standard ballasts by electronic ballasts. The results shown in Table 14 suggest that the use of low loss magnetic ballast is cost effective, but the electronic ballast is less attractive, both for commercial buildings and government buildings. Replacement of incandescent lamps by compact fluorescent lamps for hotels, hospitals and department stores is very attractive as can be inferred from the results in the table. Natural daylight has been used in traditional government and school buildings. When air conditioning is applied in a space, only electric lighting is used. The results in Table 15 show that substantial savings for offices and hospitals can be achieved if daylighting is used. However, such application implies that dimmable ballasts are used. The cost of dimmable ballasts for fluorescent lamps is too high at present.
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Table 14 Energy savings from use of electronic ballast, use of low-loss magnetic ballast, and use of compact fluorescent lamp Building
Options CL1 and GL1
Options CL2 and GL2
Options CL3
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Commercial buildings Office 4.69 Hotel 2.29 Hospital 4.98 Department 3.23 store
2.4 0.89 1.24 1.15
5.12 1.75 4.95 3.81
8 4.9 7.5 6
2.93 1.37 3.11 2.09
1.5 0.53 0.74 0.74
3.2 1.04 3.07 2.46
3.4 2.2 3.2 2.5
0.47 9.4 0.65 1.58
0.24 3.62 0.15 0.56
0.51 7.15 0.65 1.86
2.2 0.6 1.5 0.7
0.77 0.96 0.86
2.08 2.47 2.26
11.1 10.5 11.2
– – –
0.46 0.58 0.51
1.25 1.49 1.35
4.9 4.6 5
– – –
– – –
– – –
– – –
Government buildings Type 1 – Type 2 – Type 3 –
Table 15 Energy savings from daylighting Building
Option CL4
Office Hospital
25.6 12.4
Peak (%)
CL (%)
EC (%)
PB (Y)
–
26.2 11
N/A N/A
For government buildings, the IA replaced existing fixtures for fluorescent lamps by fixtures with parabolic and reflective surfaces. We do not consider this option cost effective and did not attempt to simulate this option. (d) Change in operational schedule: In some office and some government buildings, it has been observed that turning off air conditioning and switching off lighting in offices during lunch time (12:00–13:00 h) can save significant amounts of energy. The results in Table 16 show that switching off lights and air conditioners during the lunch hour and one hour prior to the end of office hours can save energy, up to 24%, for government buildings. For office buildings, the simulation results confirm savings from switching off electric lighting during the lunch hour. Such options offer savings without incurring cost. (e) Integrated retrofit: In many situations, the individual retrofit option might not afford sufficient savings to justify the cost of that option, but combining the options amalgamates the savings and lowers the overall cost. This would improve the cost effectiveness of integrated retrofit programs over and above those of individual options. A lighting retrofit reduces cooling load as well as directly reducing electricity use. An envelope retrofit reduces cooling load and can lead to reduction of air leakage. With the reduced cooling load from envelope retrofit and improvement in lighting efficiency, the size of a replacement air conditioner can be smaller. Table 17 shows the results of savings and payback times for combining options in both commercial and government buildings. Exceptional success was achieved in a number of government buildings where, in each case, the management of the office played a leading role in instituting an energy conservation
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Table 16 Energy savings from change in operational schedule Building
Option CO1 Peak (%)
Option GO1
CL (%)
Option GO2
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Commercial buildings Office 0.21 –
0.82
N/A
–
–
–
–
–
–
–
–
Government buildings Type 1 – – Type 2 – – Type 3 – –
– – –
– – –
– – –
– – –
9.22 10 10.1
N/A N/A N/A
– – –
– – –
21.7 23.5 23.7
N/A N/A N/A
Table 17 Total energy savings from integrated options Building
Options CB1 þ CB2 þ CB3 þ CA1 þ CA2 þ CL1 þ CL3 þ CO1
Options GB1 þ GB2 þ GB4 þ GA1 þ GO2
Peak (%)
CL (%)
EC (%)
PB (Y)
Peak (%)
CL (%)
EC (%)
PB (Y)
Commercial Office Hotel Hospital Department store
buildings 20.4 22.74 17.06 14.66
20.6 16.80 12.49 13.03
20.33 22.58 18.15 16.13
7.5 3 5.6 4.1
– – – –
– – – –
– – – –
– – – –
Government Type 1 Type 2 Type 3
buildings – – –
– – –
– – –
– – –
– – –
24.83 22.04 26.31
57.87 56.83 59.34
6 6.7 8
committee, which drew support from all occupants of the building in monitoring and controlling energy use. An inherently energy efficient building offers a potential for efficiency, but the successful cases demonstrated that concerted effort by the occupants is needed to achieve the promise.
7. Discussion and conclusion The ECP Act sets a clear and broad objective on energy conservation and creates the ECP Fund with an effective mechanism for replenishment. The ECP Fund Committee, as created by the ECP Act to administer the ECP Fund, performs its dual role of setting regulations for funding and funding approval and setting energy conservation policy. This dual role is passed down to each subcommittee it appoints. The main objective and requirements, as set out in the ministerial regulations or by-laws on energy conservation for designated buildings, seem to us to be clear. The assignment of the DEDP, as IA for the designated commercial building program, and the small government
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building program, is clear and appropriate. However, both programs have not been perceived to have achieved the expected potentials. Although 6 years have passed from the commencement of both programs, no report of retrofit action has been received from the designated commercial building program. An evaluation of the small government building program, completed recently, rated the success of the program at 40% and that actual savings at 46% of the predictions amounted to an internal rate of return less than the requirement of 9% set for the program. We would like to present our perception of the impediment to the success of the programs by an examination first at the technical level and then offer some views on possible remedies. First, the DEDP and the professional community have spent disproportionate attention to individual physical items of equipment. An efficient building has been observed, as perceived by the DEDP and consultants, to be synonymous with efficient air conditioning equipment, efficient lamps, efficient ballast etc. The two programs of the DEDP have not included a component to educate building management and users on the significance of their contribution to the effort. Once new equipment was installed, the management of the building was left, by each IA, to themselves. The benefit of the whole building approach as demonstrated in Section 6.2(e) has also been overlooked. Second, the DEDP did not actively solicit support from the academic and professional community to assist in the technical development. The cost and benefit of each technical option have been assessed using simple engineering calculations. No clear procedure has been developed and adopted for quantification of the benefits from retrofitting the complex components of a building envelope. Hence, envelope retrofit tends to be overlooked. Exaggerated benefits are accorded to some retrofit items proposed by consultants or the IA and approved by the DEDP, such as ceramic coatings and use of electronic thermostats. Embracing such conceptions erodes the credibility of the consultants, the professional engineering community and the DEDP. Adversely, some potentially highly beneficial technologies, such as desiccant dehumidification and alternative low energy cooling systems, may not receive support. Third, the dual role of the ECP Funds Subcommittee in setting policy and approving funds may obscure its own vision on the status and results of programs it supports. A separate body to develop strategies and plans for energy conservation would be envisaged to be able to devote itself more fully to develop better plans. The ECP Fund Subcommittee should also appoint an independent body or group to review each program rigorously and project its support on a more regular basis. In conclusion, the ECP Act has enabled Thailand to initiate significant and substantial activities in energy conservation. However, more experiences remain to be gained.
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