A comparative review on the mitigation strategies of urban heat island (UHI): a pathway for sustainable urban development

With continuous acceleration of urbanization, the complexity of the urban geometry leads to great changes in the surface albedo, which further affects the microclimates of urban areas, and gives rise to the urban heat island effect (UHI). The UHI effect results in a series of environmental problems, including frequent occurrence of abnormal weather conditions, pollution of atmospheric environment, increases in building energy consumption and even underlying dangers to urban residents. This paper proposes a critical review on the mechanisms and effectiveness of the major UHI mitigation strategies, i.e. using cool materials, arranging vegetation schemes, incorporating water bodies and optimizing the urban geometry. The review indicates that the ambient air temperature could be reduced by 1.4K∼3.74K, depending on the strategies employed. The previously available mitigation measures are more effective in summer cooling in Tropical, Subtropical and Mediterranean climates. With the increase of H/W (height-to-width) and SVF (sky-view factor), the cooling effects of vegetation, water body and cool materials are better. The review results can provide theoretical guidance to the planning and designing of buildings, and cities, the enhancement of the liveability of urban environment, and the sustainable development of future cities.