In 2018, a University of Hawaii study compared green and white roofs in Honolulu; the green roof was reported to have lower peak temperatures at the surface and nearby air

A University of Hawaii graduate student tested green roofs against white ones. The green roof proved significantly cooler than the adjacent white roof. This cooling effect extended two feet above the green roof surface. Evapotranspiration from plants cools surrounding air and buildings effectively. Green roofs offer a promising solution for urban heat island mitigation.