Every day solar energy is absorbed into roads and rooftops. This causes the surface temperature of urban structures to become 50 – 70 °F higher than the ambient air temperatures (Taha, Akbari & Sailor, 1992). As surfaces throughout an entire community or city become hotter, this in turn causes overall ambient air temperature increases. This phenomenon, known as an "urban heat island," can raise air temperature in a city by 2 – 8 °F. (Oke, 1987 and World Meteorological Organization, 1984). The hotter the air, the more the formation of ozone is accelerated.

Measures that reduce the urban temperature not only reduce energy use but also the formation of pollutants. We could reduce total energy consumed by 16.3% of base energy consumption by simply adopting reflective roofing, reflective pavement and by providing more shade trees/window shading.

Urban heat island mitigation measures can reduce energy consumption through cooling the building itself and the surrounding area. These measures include light colored surfaces (roofs and pavement) and trees, which result in direct and indirect effects on energy consumption.

 

 

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