Experimental Analysis of Cool Roof Coatings as an Urban Heat Mitigation Strategy to Enhance Thermal Performance

Driven by rapid urbanisation and global climate change, the increasing frequency and intensity of the Urban Heat Island effect poses significant risks to the health and well-being of urban dwellers across the world. To combat extreme heat and ensure a safe level of thermal comfort for urban residents, innovative and sustainable technologies, such as green infrastructure and cool roof coatings, have been incorporated into building design and urban planning. This study aims to evaluate and compare the effectiveness of six different cool roof coating brands in reducing surface temperatures under the harsh and fast-changing climate conditions in Melbourne, Australia. A pilot-sized experimental cool roof was installed on the rooftop of an existing office building to monitor surface temperature variations using a thermal infrared camera, accompanied by a statistical analysis to evaluate potential surface temperature reductions under varying weather and sky conditions. The results of this study show that the application of cool roof coatings reduced the surface temperature by at least 8.7 °C and up to 34.2 °C, corresponding to reductions of 13.2% and 53.6% from the maximum surface temperature, respectively. When comparing the six cool roof paint brands, it was observed that Brand 4 demonstrated the best performance, reducing the surface temperature to a minimum value of 34.3 °C (45.5% reduction) when the maximum surface temperature was 62.9 °C. On the other hand, Brand 5 showed the least effective performance but still achieved a reduction of 15.8 °C (25.1% reduction). This study highlights the potential of cool roof coatings as an effective urban heat mitigation strategy by lowering building surface temperatures. Alongside other urban heat mitigation strategies, such as green roofs and green walls, cool roof coatings offer a viable solution for buildings.