Too hot to stay at home: Residential heat vulnerability in urban India

Abstract

Rising temperatures may lead to deadly heat waves in India. Combined with a growing urban population and mass production of affordable housing, this can sharply accelerate the demand for space cooling. India's voluntary Energy Conservation Building Code - Residential (ECBC-R) or Eco Niwas Samhita 2018 limits thermal transmittance of the envelope. This research considers and critiques this approach through building simulation and an analysis of indoor comfort and severity of overheating during the summer months (April-May-June), in hot-dry and warm-humid climate zones. Code requirements neither vary with climate zones, nor is it adapted to future climate conditions. Our building simulations and analysis show that soon (2030s) parts of the country are likely to suffer from overheating 74% of time in summer. A minimally code compliant building would need air conditioning 90% of summer while a highly efficient iteration could reduce this by a third, in the hot-dry climate zone. Further, commonly used envelope assemblies are uncomfortably hot 77% (in the hot-dry zone) and 23% (in the hot-humid zone) of time in summer, on average. This analysis illustrates the vulnerability of current construction techniques to extreme heat and aims to avoid a long-term lock-in of inefficient, high energy consuming residential buildings.