In a bid to combat rising temperatures, hundreds of roofs in informal settlements across Ahmedabad, Gujarat have been coated with a reflective white material over the past two months. The initiative, which includes 400 households, is part of a global scientific trial aimed at understanding the effects of indoor heat on health and economic conditions in developing countries. Researchers hope that “cool roofs” could provide a low-cost solution to reduce heat stress for vulnerable communities.
The project is led by Aditi Bunker, an epidemiologist at the University of Heidelberg in Germany, and is supported by the UK-based Wellcome Trust. Bunker highlights the challenge many residents face, stating, “Traditionally, home is where people seek shelter from external elements. But now, for many, their homes are actually intensifying their exposure to heat.”
Ahmedabad’s Rising Heat Challenge
Climate change has led to increasingly extreme summers in India, with temperatures in Ahmedabad surpassing 46°C (115°F) in recent years. In informal settlements such as Vanzara Vas in Narol, where over 2,000 homes lack proper ventilation and insulation, residents struggle to cope with the heat.
For people like Nehal Vijaybhai Bhil, who had their roof painted in January, the impact has been significant. “My refrigerator doesn’t heat up anymore, and the house feels cooler. I sleep much better, and my electricity bill has gone down,” Bhil shared.
How Cool Roofs Work
The white coating applied to the roofs contains highly reflective pigments, such as titanium dioxide, which bounce back solar radiation instead of absorbing it. This prevents excessive indoor heating, providing relief to residents.
“In low-income homes, there’s often nothing to stop heat transfer from the roof into the house,” explained Bunker. “There’s no insulation barrier, so the heat just pours in.”
Before joining the study, resident Arti Chunara tried to reduce the heat by covering her roof with plastic sheets and layers of grass. Despite these efforts, she and her family often had to stay outdoors for most of the day, only entering their home when the heat became bearable for a few hours.
A Global Experiment
Ahmedabad’s cool roof experiment is part of a broader research effort spanning multiple countries, including Burkina Faso, Mexico, and Niue (South Pacific). The study aims to evaluate the effectiveness of cool roofs across different building materials and climates.
Early findings from Burkina Faso have shown promising results. Bunker’s team found that cool roofs lowered indoor temperatures by 1.2°C in mud-roofed homes and up to 1.7°C in tin-roofed homes over two years. This temperature drop also reduced residents’ heart rates, indicating potential health benefits.
The Ahmedabad trial will continue for a year, during which researchers will collect health and environmental data from households with and without cool roofs. If successful, this approach could be expanded to more regions, providing a simple yet effective solution for communities facing rising temperatures.
