Healthy Buildings 2017 Europe July 2-5, 2017, Lublin, Poland

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1 ealthy uildings 2017 urope uly 2-, 2017, ublin, Poland Paper 0011 SN: easibility Study of Zero nergy uilding for ifferent onfigurations of xisting uildings Yuka Mruyama 1,*, ei Utsumi 1, kihiro Takimoto 1, Shuhei Takahashi 1, Moe Matsuda 1, Shin-ichi Tnabe 1 1 rchitecture, Waseda University, apan * orresponding maruyama.arch@gmail.com SUMMRY To reduce energy consumption globally, it is necessary to encourage the concept of Net Zero nergy uilding (Z). n apan, the goal is to achieve Z in newly constructed buildings by 200, and the definition of Z in three stages has been established (MT, 201). urthermore, owing to the high number of buildings in apan, it is also important to encourage energy saving in existing buildings in order to reduce the total energy consumption. The aim of this study is to evaluate the energy conservation methods and the feasibility of Z in office buildings with various existing building characteristics. building model design tool was developed to model existing buildings and to calculate the annual primary energy use intensity (U) using a reference evaluation tool. t was demonstrated that even when the same energy saving method is used, the effects of the energy saving methods and the feasibility of Z differ, depending on the building configurations. YWORS office building; energy saving; building configuration; energy simulation 1 NTROUTON Recently, Z has become an important concept for energy conservation because of the rapid increase in the global energy consumption by buildings. n apan, the definition of Z (MT, 201) and the official evaluation tool "W program (uilding Research nstitute, 2012)" has been established. igure 1 shows a diagram of Z definition in apan. The definition depends on the reduction rate of the energy saving in the design stage compared with the reference value, and consists of three stages: Z Ready for, Nearly Z for 7%, and Z for. Though newly constructed buildings are the main targets to realize Z, it is also important to achieve Z through improvements in existing buildings. Volume of energy supply nergy independence Z Nearly Z 7% Z Ready nergy Savings Reduction of or more Volume of energy consumption igure 1. iagram of Z definition in apan Reference uilding

2 The aim of this study is to compare the energy consumption models, evaluate the effectiveness of the basic energy saving methods, and predict the feasibility of Z in small and mediumsized office buildings depending on the building configuration. To evaluate energy consumption, we set up a simple tool to develop the building models for input to the W program. Then, we developed 4 typical building configurations and compared the effects of the basic energy saving methods on the building configurations. 2 MTRS/MTOS This study consists of three steps based on building energy simulation: establish the building model design tool, develop the study models, and evaluate the energy consumption of the study models. We setup the building model design tool in xcel in order to develop a large number of models based on different building characteristics and to make it simpler to input the W program. This tool automatically calculates the equipment capacity of a building by selecting the building characteristics, and the calculation result generates the input of the W program. Next, we selected the building characteristics for the study models and developed models by using the above tool. Then, we evaluated the reduction effects of some basic energy saving methods on the building characteristics, and compared the Z with the reference value calculated by the W program. The W program can calculate the energy use intensity (U) of the study models and that of the reference. Outline of the building model design tool This tool automatically calculates the equipment capacity of a building by selecting the building configuration (such as, total floor area, number of floors above ground, core planning, windowto-wall ratio (WWR), aspect ratio, and office area ratio), heat insulation performance, and equipment performance. ll floor models created by the tool consist of rectangular-shaped standard floors. The equipment used in the calculation are air conditioner, lighting, water heater (in offices), ventilation (in restrooms and coffee rooms), and elevator. or the air conditioner, individual distributed air conditioning which is generally used in small to medium scale office buildings (SS, ) is assumed. The office rooms are divided into zones with floor area of 0 m 2 or less and one air conditioning heat source per zone. Outline of the study models n order to calculate the effects of introducing the energy saving method for different building characteristics and the feasibility of Z, we prepared several study models with different performances of the standard models and energy saving models for 4 typical building configurations. Table 1 lists the building configuration patterns of the test models. The building configuration patterns have 4 forms based on the building stock research (Zenrin, 201): types of floor area, types of number of floors, types of core planning, and 2 types of WWR. The office area ratio is 7% and the aspect ratio is 1:1 in all models. Table 1. uilding configuration patterns of the test models Total floor area Stories above ground ore planning (direction) Window-to-wall ratio N 00 m 2, 00 m 2, 000 m 2,,,, ore(2%) (7%) ore(12.%) (7%) ore(12.%) One side (North) oth sides (North-South) oth sides (ast-west) 28 %, 4 % ore(12.%) (7%) ore(12.%)

3 Table 2 lists the common calculation conditions of the standard models. We selected the standard equipment specifications based on the manufacturers catalog. Table 2. ommon calculation conditions of the standard models Outer skin indoor heat release quipment design condition ocation Usage ndoor temperature and humidity ir-conditioner operation time Table lists the energy saving methods. We created the energy saving models by introducing each energy conservation method of to M scenarios for the standard models. Table. nergy saving methods RSUTS Outer walls eat insulator : Polystyrene foam 2 mm eat insulating 0.98 W/(m 2 ) Roof eat insulator : Polystyrene foam 2 mm eat insulating W/(m 2 ) Window ighting quip. heat Personnel density ir conditioner ighting Ventilation Water heating levator Single pane glass 8 mm eat insulating 4.12 W/(m 2 ) Solar radiation heat acquisition rate 0.41 Validity of the building model design tool igure 2 shows the U for the standard models and the reference values. The results of the U calculation for the standard models indicate between 1 M/(m 2 yr) and 2068 M/(m 2 yr). onsidering the fact that the average reference value is 167 M/(m 2 yr), the calculation results are acceptable. f the total floor area of a given building model is small and the number of floors is high, the energy consumption of the elevator is higher than in the other configurations. n addition, since the office room of the 1 side (N) core has a large number of envelopes with windows, the consumption of the air conditioner in relation to the heat load tends to be higher than in the other core planning. Therefore, the building model design tool can be used to develop a model reflecting the building characteristics. t should be noted that the U of lighting is calculated by dividing the energy consumption by the floor area of the office room (and not the total building area). With respect to the U of plugs, a constant value is selected by the W program based on the energy consumption of the room. Tokyo Summer(2 o /),Winter(22 o /),ntermediate season(24 o /) Packaged air conditioner (OP:2.6~.4) 7:00 to 21:00 hours (Sunday, Saturday and legal holidays at halt) 20 W/m 2 20 W/m person/m 2 (S: W/person,: 64 W/person) luorescent light (40 W, umens:0 lm, illuminance:70lux) Machine ventilation (volume flow rate requirement:(rest room)40 m /(h m 2 ), (coffee room) m /(h m 2 )) lectric water heater (1.1 kw, OP 1.0) (capacity:40~900 kg, speed:4~90m/min) Scenario name tem nergy saving methods Outer walls and roof pply polystyrene foam 0 mm (eat insulating: (wall) W/(m 2 ) (roof) 0.08 W/(m 2 )) Windows pply ow- double glazing window (eat insulating: 1.44 W/(m2 ) Solar radiation heat acquisition rate: 0.2) ir conditioner pply high efficiency equipment (OP:.~4.1) Outer skin & ir conditioner Scenario & & (incruding the reduction of the heat source capacity) ighting pply illumination ( 9. W, umens:6280 lm, illuminance:70lx) ighting pply daylighting control system ighting Scenario & Ventilation pply inverter control system Water heating pply solar heat collector (% of roof area) levator pply power regeneration device PV system pply rooftop photovoltaics ( of roof area, maximum power: 167 W/m 2, angle: 0 o ) PV system pply solar windows ( of windows area, maximum power: 6 W/m2 ) M except for PV system Scenario & & & & N ll Scenario & & M

4 00 m2 00 m2 000 m2 WWR 28 % U [M/( m2 yr)] igure 2. U for the standard models and the reference values 00 m2 00 m2 000 m2 WWR 4 % U [M/( m2 yr)] Plugs Water eating Ventilation levetor ighting ir conditioner Reference U The Maximum The Minimum ffectiveness of the energy saving methods for each building configuration igure shows the reduction rate of the U under scenario to for each building configuration. We calculated the reduction rate from the U of the standard models by introducing each energy saving scenario to each standard model. n this calculation, the consumption of the plugs is excluded from the definition of Z (MT, 201). n the radar chart graphs shown in igure, it is possible to compare the effectiveness of each scenario for the building configurations. igure shows that the larger the total floor area, the smaller the difference in the reduction rate of the energy saving method for each building configuration, and the most effective energy saving method is different for each building configuration. 00 m 2 Stories above ground stroies % 2 % 2 % Total floor area 00 m m % 4 2 % 4 2 % 4 2 % 4 2 % 4 2 % WWR & ore planning(direction) 28% 28% 28% 4% 4% 4% *xcept for U of plugs igure. of the U under scenario to for each building configuration

5 The reduction rate of scenario is generally higher than the other scenarios, and the reduction rate in all the models are between 2% and 9%. The results of scenario,, and indicate that the energy saving for lighting is generally effective for the reduction of the total energy consumption in the office buildings. owever, it is more effective to introduce high-efficiency air conditioners, in addition to improving the outer skin performance, than energy saving for lighting in the configuration with the extremely small building area or large WWR value. or the model (00 m 2,, 1 side (N) core, WWR 4%), the reduction rate of scenario is 26% while that of scenario and are 22% and 2%. urthermore, the reduction of heat source capacity by improving the outer skin performance is effective since the total average reduction rate of scenario is higher than scenario by %. With respect to the improvement of only the outer skin performance (scenario and ), the average reduction rate is only 2%, which is very low especially for the configuration with a large building area; the capacity of the air conditioner should be reduced. With respect to scenario,, and the average reduction rates are 0.7%, 0.8%, and 0.%, respectively, which are also very low compared to the total consumption in any building configuration. With respect to scenario and, the average reduction rates vary between 4% and 2% and between 0.4% and 6%, respectively depending on the building area and the window area. easibility of Z for each building configuration igure 4 shows the U of the energy saving models (scenario N) and the reduction rate. t shows the reduction rate with respect to the reference. We calculated the U of the energy saving models under scenario M and N. rom the definition of the apanese Z, the consumption of plugs is excluded. The calculation results of scenario M and N indicate that the U vary between 04 M/(m 2 yr) and 89 M/(m 2 yr) and between 26 M/(m 2 yr) and 740 M/(m 2 yr), respectively. The reduction rate of scenario M and N with respect to the reference vary between 4 and 9% and between 47% and 79%, respectively. The results indicate that 4 models achieved Z Ready, while 18 models having floors each achieved Nearly Z. No model could evaluate the energy consumption by the renewable energy. The trend is that the higher the number of floors and the smaller the building area, the lower the effect of energy saving methods and the higher the difficulty in achieving Z, with or without renewable energy system. This indicates that the feasibility of Z differs despite applying the same methods to all building models. 00 m2 00 m2 000 m2 WWR 28 % -2% 2% 7% U [M/( m2 yr)] 00 m2 00 m2 000 m2 WWR 4% -2% 2% 7% U [M/( m2 yr)] igure 4. U of the energy saving models (scenario N) and the reduction rate Water eating Ventilation levetor ighting ir conditioner PV *xcept for plugs of scenario M (except for PV) of scenario N (ll methods) U The Maximum The Minimum chievement of Z Z Ready(-) Nearly Z(-7%)

6 4 SUSSON The results of the evaluation of the building model design tool for calculating energy consumption using the building characteristics have demonstrated the effectiveness of the tool. This made it possible to verify the performance of multiple buildings at the design phase. On the other hand, there is a need to develop an improved design tool capable of handling more building configurations because the shape and application capabilities of the current design tool are limited. urthermore, the current tool can only calculate the energy of the building. uilding characteristics and energy saving methods also affect the indoor environment; therefore, it is also necessary to establish an evaluation method that takes this into account. The results of the evaluation of the energy saving methods for different building configurations indicate that the energy saving of lighting is the most effective, while in some configurations, the highest reduction rate is obtained by improving the air conditioning efficiency and reducing the heat source capacity while at the same time improving the heat insulating performance. The results also demonstrate the need to consider the building characteristics in the evaluation of the energy saving methods. n terms of comparing the feasibility of the Z according to the different building characteristics using the same basic energy saving method, the results indicate that the difference depends not only on the total floor area but also on the number of floors, the core planning, and the WWR. ased on these results, we propose that building characteristics should be considered when developing the Z design method and definition. ONUSONS This research quantitatively investigated the difference in energy saving effect by introducing the same energy saving method for buildings with different characteristics and evaluating the effects. lthough energy saving of lighting is usually effective, it was shown that it is more effective for building configurations that are susceptible to the influence of heat loads from the outer skin to improve the insulation of the outer skin and to reduce the capacity of the heat source equipment. n addition, the results showed that it is difficult to achieve the Z goal in buildings with small area. ased on these results, we proposed that building characteristics should be considered when developing the design method and the definition of Z. 6 NOWMNT The authors would like to express their sincere gratitude to all persons involved in this research. 7 RRNS Ministry of conomy Trade and ndustry, Natural Resources and nergy gency, nergy onservation i v i s i o n ( ) Z R o a d M a p R e v i e w o m mi t t e e o mpi l a t i o n. uilding Research nstitute and National nstitute for and and nfrastructure Management, Ministry of and, nfrastructure and Transport (2016) W program for calculating energy consumption performance of buildings Ver The Society of eating, ir onditioning and Sanitary ngineers of apan ( ) ompleted quipment Survey orm. ZNRN O., T. (201) ZNRN igital Maps uilding Point ata of Shinjukuku.