6: URBAN GREENERY AS A MITIGATION STRATEGY FOR URBAN HEAT ISLAND EFFECT IN HIGH DENSITY COMMERCIAL DISTRICTS OF DHAKA, BANGLADESH

This chapter aims to evaluate the possibilities of introducing urban greenery to improve the thermal climate of the commercial districts of the city of Dhaka, Bangladesh, a tropical region characterized by high population density and built up areas. Dhaka had a legacy of being a green city in the past. However, due to rapid and unplanned urbanization, most of the greenery was removed for the sake of development. However, there is still a possibility to revive the green heritage of the city. This research views the Dhaka Building Construction Regulations of 2008 as a prospective means to revive greenery in the highly dense urban environment of the city. The regulation mandates 25% of the plot to be absolute soil for the purpose of ground water recharge. Nevertheless, it can also be utilized for the purpose of tree planting which will have positive effect on the overall thermal environment. In view of that, two different commercial districts were considered in this study for the thermal condition of the existing and the hypothetical situation configured according to the Building Construction Regulations and with greenery. GIS and STEVE tool, a web-based air temperature prediction model developed in the context of Singapore has been used for studying the thermal environment. The validation of STEVE tool in the context of Dhaka has been also tested through the field survey. The results showed how the new construction rules might impact the existing heat island effect and what the scope of improvement is.