Urban green roofs to manage rooftop microclimates: A case study from Sydney, Australia

Urbanisation has led to a growing need for sustainable development leading to climate resilient cities. As the urban heat burden increases in severity, technologies to improve the thermal comfort of cities are increasingly required. Green roofs are one such technology that can provide increased building thermal performance. In this study, we investigate two identical buildings, except, one was equipped with a green roof, and the other without. We present the longest-term assessment conducted on an Australian green roof with in-situ thermal monitoring coupled with surface temperature assessments. Field measurements were utilised to calculate the thermal buffer potential of the green roof compared to a near-identical conventional roof, over three seasons. Our findings indicated a reduction in rooftop surface temperatures up to 20 C when ambient temperatures exceeded 40 C, as well as improvements to heat flow of up to 55.54%. These results indicate that green roofs may contribute to the much-needed reduction in ambient city temperature to alleviate overheating and the costs associated with the urban heat island effect.