Techno-Economic Analysis of Roof Insulation Strategies for Decarbonizing Commercial and Residential Buildings in Malaysia

Building energy consumption in Malaysia has increased by 31% over the past 10 years, primarily driven by the high demand for air conditioning in response to the country's hot and humid climate. An effective way to address this problem is to increase building energy efficiency with the aid of thermal insulation. This paper presents a techno-economic analysis of roof assembly retrofits for commercial and residential buildings in Malaysia. Various roof configurations incorporating insulation materials such as radiant barriers, reflective insulation, mineral glass wool, and stone wool are investigated. The first section of this paper details the use of Sefaira building energy simulation software to evaluate the annual reduction in cooling energy consumption achieved by various roof configurations for commercial and residential buildings. Subsequently, an economic analysis is conducted by calculating the internal rate of return (IRR) and payback period for investment in each type of roof configuration. The findings show that roof assembly retrofits can reduce annual cooling energy consumption in commercial buildings by 8.65% to 16.25% and in residential buildings by 11.1% to 13.8%. Additionally, the total annual energy consumption decreases by 4.70% to 8.83% for commercial buildings, such as hypermarkets, and by 4.10% to 6.10% for residential buildings, depending on the insulation system applied. The economic analysis shows that the roof assembly insulated with a radiant barrier and thick enclosed air gap is the most economically beneficial option, offering the highest IRR of 20.60% and 6.79% for commercial and residential buildings, respectively, and the shortest payback periods of 4.6 years and 11.2 years, respectively. These results provide valuable insights to guide building owners and designers in choosing the most cost-effective type of roof insulation for new or existing projects.