Evaluating the Impact of Solar-Reflective Cool Pavements and Façades on Outdoor Thermal Conditions in a Tropical City
Authors:
Ruohan Xu, Shanshan Tong, Erna Tan, and Nyuk Hien Wong
Department of Built Environment, National University of Singapore, Singapore.
Abstract:
Reducing urban heat through climate-responsive design has become a priority in tropical cities, where high temperatures and intense solar radiation exacerbate outdoor thermal stress. Solar-reflective materials on pavements and façades have been proposed as effective strategies to mitigate surface heat accumulation and improve outdoor thermal conditions. This study evaluates the impact of cool pavements and cool-coated façades through field experiments and numerical simulations in Singapore, providing insights for their integration into urban planning.
Field experiments were conducted by applying high solar-reflectance coatings to asphalt pavements and concrete façades, increasing their reflectance by approximately 0.3 and 0.4, respectively. Mobile thermal stations were deployed to assess air temperature and mean radiant temperature (MRT) at pedestrian level (1.2 m), while thermocouples and thermal cameras captured surface temperature variations. ENVI-met simulations further analyzed the vertical distribution of air temperature and MRT from 0.3 m to 1.5 m.
Results indicate that cool pavements significantly reduce surface temperatures, while air temperature at pedestrian height exhibits a slight decrease. However, MRT at pedestrian level increases due to enhanced shortwave reflectance from the pavement surface, highlighting the need for careful material selection and urban design considerations. The study also examines the potential benefits of cool-coated façades in mitigating outdoor heat stress. These findings contribute to the development of urban cooling strategies, emphasizing the trade-offs of reflective surface treatments and their applicability across different urban contexts. By integrating these materials into long-term urban planning frameworks, cities can enhance climate resilience and improve outdoor thermal environment.