New challenge for residential building energy efficiency standards in Japan: unify energy efficiency of envelope and housing appliances

Chiharu Murakoshi, Hidetoshi Nakagami, and Mikiko Nakamura, Jyukankyo Research Institute, Japan

Keywords

residential energy efficiency standard, energy efficiency policy, energy efficiency performance of envelope, energy efficiency performance of appliance, Top Runner standards, space conditioning, water heating, lighting, ventilation, efficiency during actual operating time, measurement of home appliances

Abstract

Residential energy efficiency standards of many countries evaluate envelope performance. Japanese energy efficiency standards of residential building were revised in 1999, and include both a performance standard and a prescriptive standard for envelope energy efficiency. The target is for over 50 % of new houses to meet the standard in 2010. Efficiency of residential appliances are governed by the Top Runner standards. However, these standards consider each appliance individually, but do not evaluate the whole house comprehensively.

Because residential energy efficiency varies greatly depending on the performance of appliances, we developed a method to evaluate performance of both the envelope and the appliances, with the following characteristics. 1) Evaluate the energy efficiency of the envelope and appliance together. 2) Evaluate the energy efficiency of the whole house using total energy consumption specified for the space conditioning, water heating, lighting, and ventilation appliances at the time of construction. 3) Evaluate the efficiency for space conditioning and water heating appliances using efficiencies during actual operating time. 4) We have performed detailed measurements to understand the efficiency during actual operation. The evaluation method we developed will have a major impact on future Japanese standards for residential energy efficiency. In this paper, we discuss the composition of new standards for housing energy efficiency and explain our method for evaluating energy efficiency of household appliances.