Analysis of building envelope retrofit strategies for low-rise high-density residential housing stock in four Indian climate contexts

In India, the existing buildings are responsible for 30% of the country’s total power output. This is related to the use of electrical appliances, lighting, refrigeration, water heating and mainly to the air conditioning units. Building stocks that currently do not meet the energy standards need a retrofit and building envelope, in particular, has a big influence on the total energy demand. Thus, the focus of this paper would be on strategizing the data-driven envelope retrofitting for residential buildings using local building materials and construction techniques to reduce the existing energy demand and to increase the thermal comfort. The key to a more sustainable development is also to analyze the potential of the local Indian construction techniques and materials for efficient resource management, reducing the overall Carbon Footprint. The goal was to develop a façade retrofit plan for the existing building stock to make them resilient against climate change and parallely enhance the building energy performance. Energy need reduction is the key performance index keeping in kind the thermal comfort of the users. For this study, a post-independence (1960- 1990’s) housing complex in India (that constitutes a large share of the existing in-use housing stock) has been analyzed. The various Indian climate typologies are taken into consideration and the four main typologies (Hot & Dry, Warm & Humid, Composite and Temperate) accounting for the major coverage of the country were selected. Retrofit options for the housing stock in these climate zones are compared. Different proposals for the energy-efficient envelope retrofit were formulated: different ventilation strategies, optimized shadings and alternative properties for glazing, façade, and roof materials. Further investigation on the level of intervention and reasonable retrofit solutions with local materials show a reduction between 66 to 74 percent of total energy demand in buildings which is highest in Hot & Dry climate and lowest in Temperate Climate.