Over the last two months, hundreds of roofs in the informal settlements of India’s western Gujarat state have been painted in a reflective, white coating in order to keep their occupants cooler as the hottest time of year approaches.
The project, currently covering 400 households in Ahmedabad, forms part of a global scientific trial aimed at understanding how indoor heat impacts health and economic conditions in developing nations, and whether so-called “cool roofs” can offer a solution.
“Traditionally, home is where people have come to find shelter and respite against external elements,” said Aditi Bunker, an epidemiologist at the University of Heidelberg in Germany who is leading the project, supported by the UK-based Wellcome Trust.
“Now, we’re in this position where people are living in precarious housing conditions, where the thing that was supposed to be protecting them is actually increasing their exposure to heat.”
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According to Reuters, in recent years, Ahmedabad has experienced temperatures soaring beyond 46°C (115°F), a stark reminder of India’s increasingly extreme summers.
In the Vanzara Vas slum located in the city’s Narol area, where more than 2,000 dwellings exist, mostly airless, one-room homes residents say the white roofs are already making a difference.
“My refrigerator doesn’t heat up any more and the house feels cooler. I sleep so much better and my electricity bill is down,” said Nehal Vijaybhai Bhil, one of the participants in the initiative whose roof was painted in January.
Scientific evidence suggests that heatwaves, once a one-in-10-year occurrence before the industrial revolution are now nearly three times as likely, according to a 2022 study published in the journal Environmental Research Letters.
The white coating used on the roofs contains highly reflective pigments such as titanium dioxide, designed to bounce solar radiation back into the atmosphere rather than letting it be absorbed into living spaces.
“In a lot of these low socioeconomic homes, there’s nothing to stop the heat transfer coming down – there’s no insulation barrier from the roof,” Bunker explained.
Before joining the experiment, resident Arti Chunara said she used to cover her roof with plastic sheets and layer grass over them to keep the heat out. Yet even with those efforts, her family often had to remain outdoors during the hottest hours of the day, only retreating inside for two to three hours when temperatures dropped slightly.
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