A site experiment on the effects of cool coating in a residential community under the tropical climate

With global warming, the urban thermal environment has seen temperatures rising, especially in the tropical region, where the warming effect is twice the global average. Among the strategies for cooling cities, highly reflective coating (cool coating) stands out as a passive technology that is highly scalable and affordable. However, most of the existing studies on cool coatings are still limited to numerical simulations or bench-top experiments. Here, we provide direct evidence on the performance of cool coating in a real-scale demonstration. Cool coatings were applied to the roofs, walls and roads in a residential community in Singapore comprising of two high-rise buildings. Another two high-rise buildings were used as controls. The results indicate that cool coatings can change the energy balance of the urban surfaces, reduce the energy entering the building envelopes and the ground, leading to the maximum hourly surface temperature reduction by up to 22 °C on the concrete roof, and the outdoor air temperature reduction reached 2 °C at the pedestrian level and the mid-canyon level. The thermal comfort at the pedestrian level was improved accordingly, and the maximum hourly reduction reached 3 °C in terms of universal thermal climate index.