Modelling the influence of high-rise urban geometry on outdoor thermal comfort in Singapore

Tropical cities are exposed to high air temperature and relative humidity throughout the year, causing pedestrian thermal discomfort. In this work, we present an evaluation of the impact of urban geometry on the outdoor thermal comfort (OTC) in Singapore, focusing on a new mixed-use high-rise development. Different urban design strategies/scenarios have been analyzed: two block forms, four street orientations (N-S, E-W, NE-SW, NW-SE), four street aspect ratios (from 1.5 to 3.5) and three building height profiles (arrangement of buildings based on height). The study is based on modelling techniques. Each scenario was analyzed for seven representative weather conditions during the year. The results are analyzed with specific metrics that take into account the spatial and temporal OTC variations. The results are conditioned by prevailing low winds and high frequency of cloudy days. The best OTC levels are observed on high street aspect ratios (2.5–3) and on N-S oriented streets. Although, on a yearly perspective the streets oriented NE-SW show the worst OTC performance, deviation from the acceptable range is not high. Higher differences between street orientations are encountered for specific weather types. The outcomes provide adequate urban parameters for high-rise developments to improve OTC in hot and humid tropical regions.