Microclimatic impacts of high-rise cluster developments in Colombo, Sri Lanka

Abstract

Colombo is rapidly expanding both horizontally and vertically. With limited land and infrastructure resources, the adoption of compact forms invariably result in high-rise developments and Colombo is not an exception. Current regulation limits its scope to individual plots rather than an urban area. We map the city and its current developments utilising the Local Climate Zone system, to identify critical zones and select case studies. With a focus on microclimatic impacts at street level, we simulate selected high-rise clusters, typical podium shape changes, within a similar Frontal Area Index (FAI), using the software ENVI-met. Results show that having a block form podium and increasing building height resulted in lower mean radiant temperature (MRT) values. Reducing the FAI or removing podiums increased wind movement, yet resulted in adverse MRT effects at pedestrian levels in the immediate vicinity of the cluster. The theoretical shadow umbrella simulation option reduced MRT by a significant degree while still maintaining comfortable wind speeds. Conclusions highlight that high-rise building clusters have a significant impact on their surrounding environment. Thus, it is essential that urban planning and policy strike a balance between development goals, quality of life of inhabitants and climatic implications.