Recent climate trends show that India could suffer from deadly heat waves within a few decades, bringing portions of the subcontinent close to the threshold of survivability and accelerating the demand for cooling. The share of space cooling in peak electricity load is projected to rise sharply in India. Simultaneously, the country’s population is expected to continue to grow, peaking by midcentury. Rapid urban development, particularly mass production of affordable housing, presents an opportunity to optimize the design of building envelopes. This will minimize the demand for active cooling while keeping the inhabitants safe, even during periods of prolonged heat stress.
Heat vulnerability is a public health and safety concern. A recently launched building energy code for India, Residential ECBC (Eco-Niwas Samhita 2018) limits the thermal transmittance of the envelope. Its aim is improving thermal comfort in non-air-conditioned apartments while reducing the health-related heat wave impact. However, the code’s simplified approach has limitations, for example, requirements do not vary with climate zones within the country. Additionally, it is not adapted to future climate conditions where parts of the country are expected to be too hot in summer for over 74 percent of the time. This study focuses on indoor occupant comfort and the severity of overheating during summer, in common building assemblies in the hot and dry climate zone. The analysis intends to illustrate the problem and avoid a long-term lock-in of inefficient, high energy consuming residential buildings.