Measuring and comparing thermal comfort in outdoor and semi-outdoor spaces in tropical Singapore

Abstract

In the context of climate change, outdoor thermal comfort is an important component in many urban areas, especially in cities located in hot and humid climates. Climate-responsive urban design, including adequate building morphologies, can create novel urban spaces with better thermal comfort. In this study we compare simultaneous climate measurements taken during several months in different outdoor and semi-outdoor spaces. Results show the improvement of thermal comfort levels in semi-outdoor spaces of tropical areas like Singapore. During the midday/afternoon period air temperature in the semi-outdoor space (sheltered from solar radiation) can be reduced by ~2 °C (as a reference mean value) with respect to a non-urban reference site. However, in certain meteorological conditions the reduction can reach ~4 °C. During the same period of the day, mean radiant temperature is ~28 °C lower than in outdoor spaces of low-rise developments. The mean thermal comfort levels in the semi-outdoor space show significantly less variation during the diurnal cycle and the mean values are always within the acceptable thermal comfort range for Singapore. Mean PET differences reach ~14 °C with respect to low-rise developments. For cities like Singapore, the current study presents the benefits on thermal comfort of promoting the development of semi-outdoor spaces.