Optimum Thickness of Wall Insulations and Their Thermal Performance for Buildings in Malaysian Climate

Abstract

This study clarifies the optimum thickness of insulation materials for buildings by using the life cycle cost analysis. Common external walls including clay brick, sand cement brick and concrete in the Malaysian climate were studied. Various types of buildings including office, residential and hotel were considered. Optimum thicknesses of insulation materials including rockwool, fiberglass and extruded polystyrene were clarified. It was found that the appropriate insulation thickness in Malaysia is in the range of 18–126 mm. Different operating hours and inside-outside temperatures have a significant effect on the life cycle net saving. However, different external wall types have a slight effect on the life cycle net saving. A general index, cost/k for selecting the most cost-effective insulation material was also introduced. The material that has a higher cost/k value but a lower cost compared to other materials has the highest net saving. From all the insulation materials studied, fiberglass urethane was the most costeffective.