Urban Warming and Cities' Microclimates: Investigation Methods and Mitigation Strategies-A Review

The increased rates of urbanization and industrialization of the 20th and 21st centuries have dramatically changed the land use and cover of modern cities, contributing to the degradation of the urban microclimate and the rise of the ambient urban air temperatures. Given the multiple negative energy, environmental and social consequences of urban warming, the present paper summarizes the findings of previous studies, assessing the main causes of the phenomenon along with the key investigation methods involving experimental and computational approaches. There follows a description of the most common mitigations, and adaption strategies towards the attenuation of urban warming are described. The analyzed elements include the addition of green spaces such as trees, grass and green roofs; changes on the albedo of the urban surfaces and water-based techniques, as well as a combination of them. The discussion of the reported findings in the existing literature clearly reflects the impact of urban morphology on the outdoor thermal environment, providing also useful information for professionals and urban planners involved at the phase of decision-making.