The impact of roof systems on cooling and building energy efficiency

The excessive warming in the built environment, due to urbanization and anthropogenic heat emissions, has adverse effects on building energy consumption. Diverse technology using, e.g., vegetated roofs or innovative roof materials, have been proposed and implemented to ameliorate both indoor and outdoor thermal environments and reduce energy consumption. In this study, we apply a state-of-the-art urban canopy model to simulate the thermal performance of multiple roof technology, viz. the white, green, and hybrid roofs, in the contrasting urban environments of Princeton, NJ and Phoenix, AZ, USA. In addition, we estimate the combined energy-water saving potential for green roofs with five different irrigation schemes. It is found that green roofs can achieve a combined energy-water saving of $9.68 m(-2) roof area in Phoenix with moisture-controlled irrigation, and $5.23 m(-2) in Princeton without irrigation. These results can help to promote building energy efficiency by adapting to flexible and sustainable roof technology for heat mitigation.