Numerical Study of Effects of Wall's Insulation Thickness on Energy Performance for Different Climatic Regions of China

Abstract

Abstract Building energy consumption plays a significant role in total energy consumption in China. It is well-known that the insulation performance of the external walls of a building is a critical factor for energy consumption of air conditioning system. In this study, the effects of building external wall's insulation thickness on the heating and cooling loads of commercial buildings of five cities in China, namely Harbin, Xi’an, Shanghai, Kunming and Guangzhou, have been investigated numerically. Meanwhile, the wall's optimum insulation thicknesses of typical buildings in five cities are calculated by the life cycle cost analysis (LCCA) method. The results show that the increase of insulation thickness has a significant effect on the building heating load, inversely it exhibits a relatively small effect on the building cooling load. The analysis indicates that building energy savings are different from cities for given wall insulation and the same building conditions. For the investigated cities, Harbin achieves the largest building energy savings, and then follows the order of Xi’an, Shanghai, Kunming and Guangzhou. For the buildings in Guangzhou, the variation of energy savings is also insignificant as the insulation thickness increases. Using expanded polystyrene as insulation layer material, the optimum insulation layers of Harbin, Xi’an, Shanghai, Kunming and Guangzhou are founded to be 80 mm, 60 mm, 40 mm, 40 mm, and 20 mm, respectively.