In order to achieve further energy savings in buildings, it is essential to accurately clarify the actual situation between energy saving performance and building envelope and equipment design specification followed by taking effective policy measures. In previous surveys, highly reliable information on energy consumption has been collected through the use of detailed statements of utility bills, but in most cases only an overview of the building envelope and equipment design specifications has been interviewed due to the high level of expertise required of the respondents. Therefore, the details of the design specifications are unclear.
The purpose of this research is to analyze the input/output data from the calculation program to confirm compliance with building energy code and to find out the standard design specifications of building envelope and equipment for commercial buildings. Since commercial buildings of 300 m2 or more are obliged to report the evaluation results of the building energy code, all commercial buildings of 300 m2 or more can be surveyed.
This paper focuses on office buildings built in the financial year of 2018. A total of 1731 buildings were analyzed in this report. These buildings have been assessed for the building energy code by the Model Building Method (a simple evaluation method) and do not have a mix of building uses other than offices. The findings are presented below.
・ Analysis of the distribution of BEIm, which is a performance evaluation index for the building energy code, showed a difference in the number of buildings between BEIm = 0.55, 0.65, and 0.85. Therefore, in this report, standard design specifications were found in five groups: Group I (BEIm<0.55, 3.4% of the total), Group II (0.55 ≦BEIm<0.65, 17.0% of the total), Group III (0.65≦BEIm<0.85, 61.9% of the total), Group IV (0.85≦BEIm<1.00, 16.6% of the total), and Group V (1.00≦BEIm, 1.1% of the total).
・ The relationship between BEIm/AC, a performance evaluation index of air-conditioning equipment, BEIm/L, a performance evaluation index of lighting equipment and with or without the adoption of photovoltaic power generation, was compared for each group, and it was found that there were differences in these relationships for each group. As a result, it was determined that the energy performance of the office building can be roughly explained by the specifications of the envelope, air conditioning, lighting, and photovoltaic equipment.
・ The distribution of design specifications for envelope, air conditioning, lighting and photovoltaic equipment was compared for each group, and it was shown that there were clear differences between groups in terms of coefficient of heat transmission of exterior wall and roof, window area rate, rated capacity and rated efficiency of air conditioning heat source equipment, power consumption of lighting equipment and power generation capacity of photovoltaic equipment.
Based on the results of the above analysis, this paper identifies the standard design specifications for office buildings as of FY 2018 according to the evaluation result of the building energy code.
