These modular recycled roofs are designed to keep homes cool

In Ahmedabad, India, where the temperature rose to 108 degrees on Monday – and where the high temperatures will certainly remain above 100 for the next 10 days – it is even hotter in small huts in slums, where thin metal roofs retain heat. A local startup designed an alternative: modular roof panels made from paper and wood waste that can keep homes cooler.

“When I started the company, I traveled through four states of India, rural areas, urban slums and spoke to 600 families,” said Hasit Ganatra, the founder and CEO of ReMaterials, the startup that runs the Modroof. “And I kept seeing these roofs that were changing.” Most were made of thin corrugated iron or thin cement. “We went to villages and slums and saw people spending time outside their homes on summer afternoons, and they said, ‘This house is like an oven. We can’t stay inside. Heat stroke is common; more than 6,000 people have died in India in the past decade from heat waves.

[Photo: courtesy ReMaterials]

As climate change is heating the country, India has one of the fastest growing markets for air conditioners. (Unfortunately, the increase in air conditioning is also contributing to global warming, although new technology is emerging.) But millions of people cannot afford air conditioners. Changing the design of a small home can only help to an extent. A McKinsey report predicted that by the end of the decade, parts of India will be at risk from heatwaves so extreme that people may not be able to survive outdoors, even in the shade. But on a more ordinary hot day, if a change to a building can lower the temperature, it can make a big difference to the people who live in it.

[Photo: courtesy ReMaterials]

The Modroof design uses scrap cardboard and natural binders to create a lightweight panel that is insulated and has a coating that makes it waterproof. A metal structure makes it strong. The insulation, along with an air gap in the panel, helps keep the heat out. In tests, the company has shown that the new roof can make a home as much as 18 degrees Fahrenheit cooler than before.

[Photo: courtesy ReMaterials]

The roof is also designed to keep houses dry during monsoons; metal roofs often corrode and develop holes that leak, and concrete roofs show cracks. Ganatra visited a family after a heavy rainstorm and found them carrying all their belongings outside to dry off. “I asked them about it and they said, ‘Yes, we had to crawl into a corner of the house because it was raining and we stayed up all night.’ And this was routine for them. “

The roofs are more expensive than cheap metal plates, but cost less than concrete plates because they are easier to install. The startup partnered with microfinance companies to offer loans. (Some families paint their metal roofs white separately, a cheaper option that can also help lower the temperature.) In recent years, the company has installed 500 roofs. While the pandemic has slowed its growth, Gantra hopes its business can expand into countries in Africa and South America. “It’s very easy to ship, it’s very easy to install, it’s very easy to repair or maintain,” he says. “And we can do everything via a WhatsApp video call – we can install it anywhere in the world. We did not go outside of India, but it is only a matter of time before we do. “

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