In India – home to half a billion people living in rapidly urbanizing cities, climate change is making heat waves more frequent and intense. In 2015, a heat wave that spread across the country claimed over 2,300 lives, demonstrating that these extreme heat events can have deadly consequences, especially for India’s most vulnerable communities.

Currently, less than 10 percent of India’s households have air conditioning. Yet, as living standards rise for tens of millions of Indians, the immense increase in cooling and air conditioning demand could strain the country’s electric grid, increase air pollution, require increased fuel import, and magnify the impacts of global warming. Furthermore, with summer temperatures regularly exceeding 40° Celsius (°C) (104° Fahrenheit) (°F) in a majority of India’s cities, and large sections of the population in low-income housing with little to no access to electricity, availability of cooler homes is a matter of survival, not just comfort.

Urbanization brings with it skyrocketing development that converts open spaces into paved, heat trapping surfaces like roofs and roads. More than 60 percent of the roof surface in urban India is constructed from galvanized metal, asbestos, and concrete. Collectively, these hot surfaces can exacerbate the heat island effect and worsen air pollution.

More than 65 million people in India live in informal urban housing, known as slums or bastis.6
According to the Ministry of Power’s Bureau of Energy Efficiency, low-rise buildings like these can absorb up to one-fifth of a building’s heat through the roof. Roofs, therefore, offer an avenue to significantly impact internal temperatures and provide indoor thermal comfort, in both air-conditioned and non-air-conditioned buildings. Cool roofs, with their specific characteristics, are better at reflecting solar radiation and emitting absorbed heat. Depending on the setting, these cool roofs can help keep indoor temperatures lower by 2 to 5°C (3.6 – 9°F) as compared to traditional roofs, offering simple and effective protection from extreme heat especially for vulnerable communities in low income housing. Additionally, cool roofs may help save energy, bring down cooling costs, and lead to curbing air pollution and climate change in the long run.

Cities can lead the way in cool roof implementation. In 2017 and 2018, the cities of Ahmedabad and Hyderabad initiated pilot cool roof programs. These initial programs include citizen awareness campaigns, pilot initiatives targeting 3,000 roofs, cooperation with businesses, and applying cool roof techniques to government buildings and schools. These new programs build on programs and policy efforts in cities like New Delhi, Indore and Surat; research from leading subject matter experts at leading institutes like the International Institute of Information Technology, Hyderabad (IIIT-H) and Indian Institute of Public Health, Gandhinagar (IIPH G); as well as lessons learned from cool roof programs around the world.

Garg, Vishal; Brahmbhatt, Bijal; Bhagavatula, Laasya; Ruehl, Henry; Awasthi, Amartya; Kwatra, Sameer; Sarkar, Sayantan; Bilolikar, Rajkiran V.; Chinta, Sree Sowmya; Ganguly, P.S.; L.M., Sathish; Selvakumar, V.; and Singh, Srishti