“Optimisation of canyon orientation and aspect ratio in warm-humid climate: Case of Rajarhat Newtown, India”

Abstract

This study investigates the impact of different orientations and canyon aspect ratios to improve street-level microclimate in a warm humid climate. It also contributes to the development of a methodology to develop design guidelines while planning urban neighborhoods. The study was carried out using ENVI_met version 4.0. Simulations were run for typical residential neighborhoods in the Rajarhat Newtown, Kolkata, India, characterized by a warm humid climate as per the National Building Code of India, for a typical summer day with a high level of discomfort. Different orientations and different canyon aspect ratios are simulated and compared to find the most suitable design alternative for the study area. The floor area ratio has been kept constant in order to keep the design alternative more realistic. Performance analysis of the design alternatives was carried out by comparing air temperature, wind speed, MRT and PET. It was found that an orientation angle between 30° and 60° with the wind direction and a Canyon Aspect Ratio of 2.5 can reduce the PET value by 5 to 9°C throughout most of the study area during a mid-afternoon summer day. Improvement in the thermophysical assessment classes cannot be achieved for the adopted simulation date and time (May 31st, 14:00h).