Urban shading: a design option for tropics? A study in Colombo, Sri Lanka

Recent urban microclimate studies in Colombo, Sri Lanka, indicate that the maximum daily temperature within street canyons decreases with increasing height to width (H/W) ratio, but higher H/W ratio negatively affects street-level wind flow. There is also evidence pointing to the cooling effect of sea breeze. The nocturnal heat island is small in contrast to daytime urban–rural differences. In this paper, we use the software ENVI-met to simulate the effect of different urban design options on air and surface temperatures, as well as on outdoor thermal comfort. The latter is expressed as the physiologically equivalent temperature (PET), an index based on air and radiant temperatures as well as wind and humidity.