The Effect of Urban Form on the Heat Island Phenomenon and Human Thermal Comfort: A Comparative Study of UAE Residential Sites

Abstract

The Urban Heat Island (UHI) has a detrimental impact on human thermal comfort and the health of city dwellers through raising average temperatures. Urban geometry is one of the factors that affect the intensity of the UHI phenomena. The purpose of this research is to evaluate and compare traditional vs. modern urban forms with respect to temperature and thermal comfort in the United Arab Emirates. Three of each were chosen based on their densities and form. Traditional buildings in the UAE differ from others in the Middle East in that they are primarily single-story, while in the surrounding countries of the region, such as Iran, Iraq, and Saudi Arabia, they are mainly two stories. The UAE climate also has its distinct characteristics. Each configuration was investigated using the ENVI-met urban microclimate simulation software. The comparisons were made for three seasons: summer, winter, and spring. Each configuration was evaluated through four parameters: building shape, street geometry, orientation, and urban density. The results revealed that the low-density traditional urban form exhibited the lowest air temperature in August because it has a low sky view factor (SVF), high height-to-width ratio, and less density. The highest ambient temperature was observed in the sites with low-medium density, lowest height/width ratio, and maximum SVF. The high-density modern urban form displayed lower air temperatures in the summer season than the low and low-medium-density modern urban sites due to the building form, high height-to-width ratio, low SVF, and wind corridors. The traditional compact urban form in Al Fahidi, which has the highest urban density of the six configurations, achieved the best thermal comfort levels in the summer due to the sizable height-to-width ratio and lowest SVF.