Key Points for Energy Calculation in Japan, Aiming at Realistic Evaluation of Building Energy Performance

Transcription

1 Key Points for Energy Calculation in Japan, Aiming at Realistic Evaluation of Building Energy Performance Takao Sawachi, Dr. Eng. Director, Building Dept., NILIM-MLIT, Japan Contents 1. Background Expected role of energy calculation for buildings 2. Core part of the presentation Key points to enable the role 3. Toward the near future First step of validation The contents contain personal views of the presenter, and do not necessarily represent the view of NILIM nor MLIT. This work is supported by JSPS KAKENHI, Grant-in-Aid for Scientific Research (A), Grant Number JP

2 Japan s Target to reduce GHG emission By 2050, 80% By FY2030, 26% compared to FY2013 Japan s Target for Sectors by 2030 (million t-co 2, energy originated): Industry Transport Commercial and other % reduction Residential % reduction How to achieve the target for building sector: De-carbonizing electricity, of which share is 50% in building sector (energy demand base) reduction by 25% (rough estimation) Improving energy performance of buildings reduction by 20% (rough estimation) Source: Billion liters For Building Sector Primary energy supply Renewable Nuclear power Natural gas Coal LPG Oil Renewable Nuclear power Natural gas Coal Oil 2

3 Old energy standards New energy standards started in 2013 Total primary energy use is a principal index Web-program for the calculation is available Building Envelope Building Envelope 3

4 Expected role of energy calculation in Japan To give realistic prediction of energy consumption by higher correlation between calculation and real energy use 4

5 Web-program for non-residential building Web-program for residential building Statistics of access (2015) Main Site 790,000 Non-residential program 1,930,000 Residential program 5,280,000 5

6 Key point #1: Full description of logic, equation and constant, by which third persons are able to even reproduce program full transparency of evaluation for various industries and products easier identification of needs for improvement and software bugs easier succession through generations of expert For non-residential For residential 735 pages 1,082 pages Books explaining logic of energy calculation 6

7 Key point #2: Importance of assumptions on usage of building and equipment, which have dominant influence on weight of various design factors Schedule, area and set-point temp. & humidity for space heating & cooling Ventilation rate and schedule Internal heat gains and schedule Usage of domestic hot water and schedule Lighting requirement and schedule Usage of elevator ISO Schedule and condition for non-residential buildings ISO DIS Schedule and condition for residential buildings 7

8 Key point #3: Evidence-based utilization of appropriate properties of equipment Properties and their test protocols have been defined mainly for relative comparison of products only of the same kind. When such properties are used for estimating absolute energy use and for comparing across different kinds of equipment in energy calculation, unbiased prudent utilization with evidence is indispensable. The followings are examples. For heat pump air-conditioning systems, COP at rated condition(s) has been used instead of synthesized properties such as APF and SEER. Partial load and outdoor temperature are considered when determining the efficiency at each period of energy calculation. For boilers of DHW systems, partial load and intermittence of operation are considered. For heat pump DHW system with tank, correlation between COP based on JIS C 9220 and more realistic test during 31 days for each seasons is used. For energy recovery ventilator, sensible or total effectiveness, net supply airflow ratio, supply and return airflow rates are used for calculating heating or cooling load due to ventilation. 8

9 Key point #4: Any energy-saving technique must have its own design standard and the like in order to be incorporated in energy calculation. Examples: Natural ventilation for reducing cooling load in non-residential buildings cannot be evaluated yet due to inexistence of its design standard. Demand control ventilation for habitable rooms such as CO 2 control of fans cannot be evaluated, either. Variable volume control of fans and pumps can be evaluated but very moderately (linear relationship is assumed between partial load and electric consumption). Ground heat source air-conditioning system of limited kinds has just been incorporated in energy calculation, thanks to the development of its design standard. Continuous development of design standards by collaboration with industries is on-going. 9

10 Key point #5: Conformity judgement procedure throughout design and construction process As the first step, the compliance to the standard shall be mandatory for non-residential building, of which floor area is not less than 2,000 m 2 from April Importance is on the social system for conformity judgement including checking agreement between building drawings & specifications and input data for energy calculation, as well as on checking change of building & system design during construction. Affordable process by simplifying the content of calculation, as far as it does not destroy the credibility of the energy calculation. 10

11 Primary energy use (actual reported value) MJ/household/year An example of comparison between primary energy uses by calculation and report (actual energy use) for zero energy houses using subsidy 85.6% of all houses (N=1090) are actually zero energy house (as definition, only space heating & cooling, ventilation, DHW, lighting, FC and PV are considered). Data for zero energy non-residential building (using subsidy) will be collected and analyzed soon. Primary energy use (calculation by web-program) MJ/household/year Region1,N=10 Region2,N=7 Region3,N=44 Region5,N=282 Region6,N=562 Region7,N=86 Region4,N=94 Region6,N=5 11

12 summary Target of reduction in GHG emission for building sector is an urgent problem for building industry and experts in building energy calculation. Expected role of energy calculation in Japan is to give realistic prediction of energy consumption by higher correlation. Web-programs are available, and there are key points #1 to #5 to accomplish the above-mentioned expected role. Validations of credibility of energy calculation have been done. The results should be utilized to find ways for improvement. 12