The optimum thickness and energy saving potential of external wall insulation in different climate zones of China

Heat transfer coefficient of external wall has signature impact on heating and cooling demand. Changing thickness and material of insulation layers is direct way to improve the heat transfer coefficient of external wall. In this study, the formula which could be used to calculate the optimum thickness of thermal insulation layer for external wall is discussed with the consideration of climatic condition, heating and cooling equipment and insulation materials. Urumqi, Beijing, Shanghai, Guangzhou and Kunming are chosen as typical cities in different climate zones of China. The optimum thickness in these cities is calculated by formula and compared with required thickness in Chinese energy saving standard. Average yearly cost in material life-cycle is involved as an important factor. Result shows that, there is great potential of external wall in each climate zone to reduce heating and cooling demand by increasing the thickness of insulation layer and using better material.