Review on the cooling potential of green roofs in different climates.

The combined trends of urban heat island (UHI) intensification and global warming led to an increased tendency towards on the greening of cities as a tool for UHI mitigation. Our study examines the range of research approaches and findings regarding the role of green roofs in mitigating urban heat and enhancing human comfort. This review provides an overview of 89 studies conducted in three main climate types (hot-humid, temperate, and dry), from 2000 till 2020. All of the reviewed studies confirm the cooling effect of green roofs and its contribution to reduced heat island intensity regardless of the background climatic condition. However, dry climate has the highest (3 °C) median cooling effect of green roofs among all the climates investigated. Hot-humid climate presents the lowest cooling potential (median = 1 °C) of green roofs among all the climate types. Moreover, green roofs contribute a median surface temperature reduction of 30 °C in hot-humid cities. This value is relatively low for temperate climates (28 °C). Notably, no study has examined the impact of green roofs on surface temperature reduction in dry climates. This review can benefit urban planners and various stakeholders.