Design Guidelines for Residential Shape

This paper discusses how to reduce the average external thermal insulation value（UA value） through the method of increasing the residential external area from view of Japanese designers and policy makers. The UA value is an important residential thermal parameter in Japan, but there is a lack of discussion on its relationship with the shape of the house or the external area. In this research, We categorized two main way of changing external area and used a method of Modular analysis and Comparative analysis with 360 cases ,we find that UA value is strongly connect to external walls (R2＞0.8) and can be reduced by 10-15% by expanding external walls in normal cases, but a side effect of the sharper increase of total heat loss will appear. Therefore, this paper proposed a guideline of achieve best thermal evaluation in the current regulation and suggests that designers should only consider reducing the UA value by increasing the external area if the UA value is close to the requirement of the energy-saving benchmarks, or if it is difficult or costly to change the construction, and that designers should give priority to reducing the UA value by adjusting the ratio of the area of the upper and lower floors, which is a more economical way to reduce the growth of energy.