EVALUATION OF ENERGY SAVING METHODS IN A RESEARCH INSTITUTE BUILDING, CCRH

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1 EVALUATION OF ENERGY SAVING METHODS IN A RESEARCH INSTITUTE BUILDING, CCRH Michiko CHIKADA 1, Takashi INOUE 2, Takao SAWACHI 3, Yutaka GENCHI 4,Toshiaki ICHINOSE 5 1 Government Buildings Department, Ministry of Land, Infrastructure and Transport, Japan 2 Department of Architecture, Faculty of Science and Technology, Science University of Tokyo 3 Building Research Institute, Japan 4 Research Center for Life Cycle Assessment, National Institute of Advanced Industrial Science and Technology, Japan 5 Center for Global Environment Research, National Institute for Environment Studies, Japan Ministry of Land, Infrastructure and Transport, Japan Azuma Tsukuba-city Japan Tel.: , FAX: tim1967@cj8.so-net.ne.jp ABSTRACT: As Japan is in the Asian monsoon area, the reduction of air-conditioning energy consumption in summer and the middle seasons, and in particular the conflict between solar-shading and daylight use is an important research topic. The aim of this study is to verify the applicability of a number of technologies for reducing energy consumption at the Climate Change Research Hall, CCRH, the building of the National Institute for Environmental Studies, Japan. The project has two paticular aims, 1) To monitor the effect of advanced energy saving technologies on the reduction of the impact for indoor and outdoor thermal environment with emphasis on the control of solar shading and day-lighting and natural and cross ventilation techniques. 2) To monitor the effect of the surface heat balance on the rooftop to estimate the impact on the urban climate as a storage heater. Conference Topic: 3.4 Monitoring 1. INTRODUCTION Increasing awareness of environmental issues has lead to development of a large number of energy conservation technologies for buildings, especially in advanced countries such as the EU nations and the USA. In Japan, however, especially in the office buildings, those methods are difficult to put to practical use because those were developed for saving heating energy, although the main point is to save the cooling energy in Japan. But also, in Japan, so many saving energy methods have been developed, and those attempts are made on positive policies like the standards for planning the eco-builiding by the Government Buildings Department, Ministry of Land, Infrastructure and Transport. In these standards, about 50 methods and technologies were introduced with their own calculation formulas and points of election. But effectiveness of a few of these methods are confirmed on the definite plans because these were developed in recent years. In many cases, these methods were set up in buildings not considered either suitable or not to scale and/or type of buildings. It is necessary and important to consider a detailed monitoring and analysis for that. Some methods, considered as effective for the actual building, CCRH, were set up and the effectiveness of those methods will be researched for more than three years after it is in use. Furthermore, a guide to using the adopted building and detecting the working styles in it for improvement of those energy saving methods and technologies will be made. In this paper, what and how to choose methods and technologies for this building, the ways and purposes of this research, and how the various details were set up will be presented. 2. OUTLOOK OF STUDIED BUILDING The CCRH, which is one of the research at the National Institute for Environmental Studies Japan, was opened in May It is a three story RC structure with a floor area of approximately 4,900 m2. The orientation of the building is such that southerly winds are incident on the facade, and the south section of the eastern wing faces the magnetic South Pole, as shown in Figure 1. The south side of the building consists of mostly office space, while the north side, separated from the south side by corridors, contains the laboratories, each with their own particular air conditioning system. The project will be undertaken in the south side of the building, since the aim of the research is to analyze techniques for Japanese office buildings. Details of the methods and technologies used in the study are shown in Figure 2.

2 Figure 1: Plan of Building, CCRH Figure 2: Adopted Methods and Technologies

3 (outer) Low- 6 mm + air 6 mm +(inner) 6 mm (outer) Low- 6 mm + air 6 mm +(inner) TT 11 mm (outer) TT 11 mm + air 6 mm +(inner) Low- 6 mm (outer) 6 mm + air 6 mm +(inner) Low- 6 mm (outer) 6 mm + air 6 mm +(inner) 6 mm (outer) Low- 6 mm + air 6 mm +(inner) TT 6 mm (outer) 6 mm Figure 3: Glass 3. MONITORING STUDY Building performance will be evaluated with respect to indoor/outdoor thermal behavior as part of an annual monitoring program. The impact of each envelope component or system on the overall building was predicted during the design phase and will be monitored for 3 years following the completion of construction. The main principles of the CCRH design are described below. Monitoring will be carried out mainly in a room on the 3rd floor in the east wing. (See Figure 1) 3.1 Combination control of solar shading and daylighting [Corresponding resercher: Dr Takashi Inoue] In office buildings in Japan, because heat is generated from a large number of heat sources such as workers, computers, lighting and office equipment, as well as from solar radiation passing through the windows, the amount of energy required for cooling is much greater than that needed for heating. Therefore, solar shading is of primary importance. On the other hand, in winter, sunlight can be used as a heat source in order to reduce the amount of energy needed for heating. Because energy for lighting accounts for approximately 1/4 of the total energy consumption in office buildings, by reducing the amount of energy used for lighting, it is possible to reduce not only electric power consumption but also the cooling load. The authors have solved this complicated problem by developing a window system that combines an air-flow type window with built-in automatic slat-angle control blinds and an artificial lighting control system, and satisfactory results were obtained (ref.1&2). However, some problems remain, such as cost due to the complexity of the system, and the need for different approaches has also been recognized with respect to the diffusion of solar shading and natural light utilization. In response to these needs, the fenestration of the CCRH building was designed so as to reduce energy consumption by adopting a newly developed autonomous response-type dimming glass known as thermotropic glass, i.e. TTglass, and by appropriately combining this TT-glass and a low- coating, a cavity between the glass panes, and a canopy. Without the need for inputs from sensors or control equipment, Figure 4: Glass, Balconies and Canopies out A in TTE+FL Figure 5: (opaque) A TT+LE A LE+TT FL+Blind FL:Usual float glass TT:Thermotropic glass LE:Low-e coating A :Air gap Comparison of inside surface temperature of windows

4 the TT-glass autonomously changes state from clear and light-transmitting to opaque and light-scattering in response to changing environmental conditions according to the time of day, weather, and season. The effect of solar-shading and day-lighting of TTglass was evaluated by preliminary experiment using an infra-red camera, and numerical simulations of the energy for lighting and air-conditioning. Figure 5 shows the surface temperature distribution in the university for a typical sunny day. The surface temperature of the usual window(fl+blind) is as high as 42, whereas that for the TT-glass is no higher than 37.For the energy consumption simulation, the revised HASP-L program, dynamic heat load hour-byhour calculation program which enables assessment of the natural light utilization, was used based on standard weather data for Tokyo. The results (Figure 6) show that significant reduction in energy consumption could be expected by selecting an appropriate glass. Energy for Lighting Air-conditioning Load(MJ/m 2 a) Primary Energy (kwh/m 2 a) Heating Cooling Consumption (MJ/m 2 a) Solar-shading Low-e FL+TT LE+TT FL+TTE Figure 6: Influence of glass on energy consumption (Tokyo, model office, south, without canopy) Compared to the air-flow type window system, TTglass cannot provide the same effect on lighting, and visibility cannot be maintained under opaque and light-scattering conditions. However, use of this glass can drastically simplify the system because it does not require a solar shading mechanism or control system, and generalization to various installation applications seems quite feasible. The practical use of balconies and canopies to cut direct solar radiation and the use of clear glass, will satisfy the amenity for the workers. (See Figure 4) Other kinds of glass have also been installed to investigate the optimum way to combine control of solar shading and day-lighting for each season and each solar altitude. The effect will be evaluated by means of experiments using infra-red camera, numerical simulation, and survey questionnaires answered by the building s occupants. 3.2 Natural ventilation and cross ventilation [Corresponding resercher: Dr Takao Sawachi] In the design stage, a network simulation program was used to predict airflow rate through openings in summer conditions. As input data, existing information of wind pressure coefficient was utilized with hourly data of wind speed and direction near the building site. The natural ventilation technique was chosen to be applied to the southern side rooms on the 2nd and 3rd floors. (See Figure 7) Prevailing wind direction on site in summer is from the south, and the symmetrical east and west wings of the building seem to be appropriate to catch the wind to have a larger positive wind pressure. The vertical surface facing the north is used to position outlet openings, which tend to have a negative wind pressure. The tilted roof is expected to accelrate the exhaust force, namely negative pressure on the northern façade behind the roof. The space above the third floor rooms is used as an airflow path between the rooms and the north face openings of the roof part. As for the second floor rooms, the hall and stair case are used as the airflow path. The south window of each room is divided into smaller windows installed at a higher position and larger windows below the smaller ones. In daytime, both windows are supposed to be Figure 7: Wind Routes

5 used, while at night mainly saller windows are supposed to be opened for safety reasons. Besides the doors between halls and rooms, there are galleries, which function as an airflow path. In office spaces, indoor climate control will be done by occupants, who may have different behavioural patterns and thermal sensations. Then, the usage of natural ventilation to keep the environment comfortable will be decided by occupants and some of the office spaces can be air conditioned. Taking such situations into consideration, the independence of the air conditioning system in each room is kept as much as possible. In the measurement for the validation, related factors to ventilation will be measured, including outdoor wind conditions, wind pressure on the building envelope, ventilation rates, temperature distribution, indoor air movement and so on. On CCRH, there are systems for setting the pressure meters to check the characteristics of wind on the ceiling near the windows between the column spans on the 2nd and the 3rd floor. 3.3 The impact on the urban climate [Corresponding resercher: Dr Yutaka Genchi] During summer, the peak electric power load rises by about 1.6 GW for each 1 degree C rise in air temperature in Tokyo. When large amounts of solar panels, tree-plantings, and high-albedo panels are introduced on rooftops or wall surfaces in the entire Tokyo area, the surface heat balance will change and that would cause some changes in the air temperature levels. When air temperatures decrease in the summer, more energy saving could be expected because of diminishments in the cooling load. We will measure the surface heat balance on the rooftop of CCRH and monitor the cooling and heating loads beneath the rooftop to decide parameters of simulation models when solar panels, tree-plantings, and high-albedo panels are introduced so as to estimate these effects by our developing urban climate simulation and building energy consumption simulation, On CCRH, there is a system of steel frame stand to set the temporary units like roof tree-planting and solar panels on a certain area of the roof. And below this area, from behind the roof structure, there are 18 holes (6.5mm :each depths are 1cm, 3cm or 5cm from the surface) to set the heat sensors. (See Figure 2 and 7) 3.4 Other adopted technologies In CCRH, the following technologies are adopted. 1) Roof-planting. (permanent) 2) Solar panels. (Used to water the trees on the roof) (permanent) 3) Solar walls. 4) Lighting control 5) High-albedo paint 6) SUDARE, the Japanese traditional bamboo blinds. The study has begun by collecting definite data since May of this year, after the building was completed in April. Before that, the effectiveness of energy conservation had been predicted, especially the cooling energy because the reduction of airconditioning energy consumption in summer is a serious subject in Japan. CASE 1 is the situation under the assumption which all those methods or technologies would not be installed. The other cases were set to grasp the efficiencies of each technology. The last one, CASE 8 is the most similar case to this actual building. (See Table 1) The calculation program is the SMASH, which was developed at The Building Research Institute, Japan. The weather data, such as every-hour wind velocity, was measured by the Meteorological Research Institute, Japan, which is situated in a nearby building. The conditions, such as insulation, room air conditioning input in this program, are shown in Table2. Table1: Comparative Supposition methods CASE 1 (non-eco model) CASE 2 CASE 3 CASE 4 CASE 5 CASE 6 CASE 7 CASE 8 (eco model) Table2: Conditions January average temperature 2.5 Ž August average temperature 25.5 Ž heating time November cooling time June wall insulation polystyrene form 25mm(inner) roof insulation hard urethane form 25mm(outer) 3F 2F 3F Offices 2F offices (outer) +air +(inner) glass West Wing (outer) Low-e + air + (inner) Low-e +air +(inner) TT 6.5mm pent roof night purge East Wing 3F offices 2F offices natural ventilation / cross ventilation roof plantin g 3F 2F 4. THE PREDICTION OF ENERGY CONSERVATION Figure 8: Modeling

6 The rules of conditions were set as follows because of the restricted program. 1) Each room in the same wing has the same air conditioning and natural ventilation condition. Therefore, one air-conditioning zone was as in one room (See Figure 8) 2) TT-glass should always be dimmed. 3) The annual cross ventilation rate, while being naturally ventilated, is 5 per hour. 4) An average value was used for roof-plantings. Although the efficiencies of light shading of plants themselves and photosynthesis are not considered, effects of evaporation and radiate are taken into account. The effectiveness of energy conservation in cooling time is shown in graph 1. As the graph shows, the cooling load would be halved compared to the non-eco case. The effectiveness is remarkable in CASE 7, being considered natural ventilation. It can be said that it is necessary to consider the wind effects in this area where 60 percent of wind is faster than 2m/sec, and prevailing wind direction is south- east to south in summer. Because of the program, the effectiveness of the wind would be much bigger than actual, therefore, calculating verification and improvement of this program is one subject of this study, as is the measurements. In the hottest season, which would not compensate the rise in temperature with increasing of the wind velocity, it is appropriate to control the inner climate by cool air conditioning. So it is necessary to determine the proper use of the natural ventilation or cooling based on the actual circumstances surveyed to earn the calculated conditions to presume the efficiency of cooling energy reduction more accurately. Because so much equipment become overheated in this office building, it is confirmed that this equipment effected the cooling load a lot, and it also may reduce the heating load in the winter. cooling load [MJ/year] 300, , , , ,000 50, % incorporates the proposed systems. The data will be analyzed from different viewpoint such as energy conservation, indoor thermal environment and urban climate, and regulate their merits and demerits systematically with the consideration of influences of those methods. Following completion of this study, it is anticipated that the results will be used to amend the current design standards. REFERENCES [1] Takashi INOUE; Combination Control of Solarshading and Day-lighting for Office Buildings, International Building Physics Conference 2000, pp [2] Advanced Envelopes; International Energy Agency Annex32 (2000), T.INOUE, P.Baker et al, pp50-59 [3] T.INOUE, and T.IBAMOTO, 1993, APPLICATION OF NEWLY DEVELOPED WINDOW SYSTEM TO OFFICE BUILDING, CIB, Energy Efficient Buildings, P [4] Tokyo Electric Power Company, TEPCO ILLUSTRATED (1999), pp162 0 CASE-1 CASE-2 CASE-3 CASE-4 CASE-5 CASE-6 CASE-7 CASE-8 Figure9: Comparison of Energy Conservation 5. CONCLUSION This paper has introduced a three-year study at the CCRH to verify the effectiveness of energy conservation system. In this building, monitoring of the temperature, radiation, light, the air flow, and the energy consumption, and the questionnaires for office workers will be made over a period of the three years, with particular emphasis on seasonal variations. An important feature of this project is that the building under examination is representative of an actual Japanese office block and the building design