Role of built environment on factors affecting outdoor thermal comfort - A case of T. Nagar, Chennai, India

Abstract

Background: Urban morphology plays a critical role in controlling the factors that influence outdoor thermal comfort. This research aims to quantify the impact of urban growth pattern characterized by orientation, ground cover, street geometry etc. on variations in climate parameters. Method/Analysis: Air temperature and relative humidity data were recorded in nine different locations of the study area (T. Nagar, Chennai, India) characterized by different urban morphology on a typical winter day. The data collected were simulated using Rayman Pro to analyze the impact of sky view factor, height to width ratio on thermal comfort parameters. Also the relationship between the spatial distribution of the recorded values and urban morphology were analyzed. Findings: The results of the study establish a clear relationship between urban character and microclimate modifications. The distribution curve of air temperature and humidity establish high thermal stress during day time in high activity zone due to anthropogenic heat and hard surfaces. The isotherms clearly reinforce the presence of urban heat island effect in dense areas during night time attributed to lesser opportunity for re-radiation. Further wider streets show high difference in the diurnal temperature which in turn create cool pockets. The role of urban parks and vegetation in improving the comfort conditions are clearly evident in the study. Applications/Improvements: The study can be applied on the Local Climate Zone (LCZ) map of tropical city of Chennai. This will help in establishing a new development control rules for the city which will be responsive to the Micro Climate.