Air pollutant dispersion around high-rise building cluster forms: the case of Port City, Colombo, Sri Lanka

Abstract Air quality in dense urban environments is a growing concern, especially in rapidly developing cities. In the face of growing traffic associated with urbanization, there is evidence for high levels of pollutant concentration at street level which is influenced by building forms. In this paper, we examine the potential effects of high-rise, cluster developments permitted by the local planning authorities in the newly established Port City development in Colombo, Sri Lanka. We designed possible building forms based on specific guidelines for the development in terms of plot coverage, floor area ratio, and maximum height. The three-dimensional building clusters were simulated using the RANS k-epsilon turbulence model, to determine pollutant dispersion of a complex street formation in a high dense high-rise building cluster, within the development and the surrounding context (existing Colombo). Results show that in a complex building cluster there is no single building form which will provide uniformly better pollution dispersion across the development. Flow patterns are significantly affected by the building morphology, context, and ambient wind direction. Thus, individual building permits should be considered in their contexts and surrounding geometries need to be accounted for.