Multi-scale evaluation of cool façade paints for tropical built environments: real-world impacts on thermal performance, building energy, and precinct microclimate
Authors:
Shanshan Tong, Shuyan Zhang, Yu Qian Ang, Marcel Ignatius, Ruohan Xu, Joie Lim, May Lwin Oo, Erna Tan, Nyuk Hien Wong
Abstract:
Cities face increasing pressure to accelerate building decarbonization while mitigating urban heat islands. Although cool façades are a promising heat-mitigation strategy, empirical evidence of their multi-scale thermal and energy performance in dense, operational urban settings remains limited. This study addresses that gap through a field evaluation of solar-reflective coatings applied to 49,860 m² of building façades on a tropical campus in Singapore. Our multi-scale monitoring captured façade thermophysical performance, cooling loads, near-façade thermal conditions, and precinct-scale microclimates. The (cool) coatings reduced external and internal wall temperatures by up to 7.1 °C and 3.3 °C, respectively, and lowered conductive heat gains through walls by up to 48% on sunny days. Cooling loads declined by 7.4% over a three-week post-retrofit period and by 12.4% on sunny weekdays. Difference-in-Differences analysis further identified average and peak ambient air temperature reductions of 0.27 °C and 1.0 °C, respectively, supporting cool coatings as a scalable, low-cost retrofit strategy for tropical cities.
Keywords:
Building facade; Cooling load; Microclimate; Solar-reflective cool paint; Thermal comfort