06-05-2025
Low-cost eco-roofs may help cool informal settlements by up to 6°C
New Delhi: A new report on urban heat resilience in Delhi's informal settlements, based on on-ground insights, suggests the use of low-cost, multi-layered roofs made from localised materials, including bamboo, jute and cardboard.
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These roofs can reduce indoor temperatures by 2 to 6 degrees Celsius of the outside temperature, stated the report.
The report, Heat Solutions: Unboxing Learnings on Heat Resilient Housing from Urban Poor in Delhi, by Chintan Environmental Research and Action Group was released on Tuesday. It offers insights into how climate resilience can be built where it's needed most—in informal settlements vulnerable to rising heat.
According to the report, roof-type models were implemented in the identified wastepicker settlements in south and central Delhi. "Model 2, which used a layer each of tarpaulin, existing tin, insulation sheet, cardboard, bamboo and jute, was the most effective," it pointed out.
Under model 1, a layer each of tarpaulin, existing tin, insulation sheet, thermocol, bamboo and jute were used as a roof. "It was found that the temperature was 5°C less than outdoors, and 12°C less than a non-installation house (without such roofs)," said the report.
Under model 2, the roof uses tarpaulin for waterproofing and retains the tin roof, but substitutes thermocol with cardboard for insulation, making it a more environmentally sustainable option. The insulation sheet, bamboo and jute are used similarly to model 1, providing insulation and structural support.
"In this model, the temperature was 6°C less than outdoors and 13°C less than a non-installation house. However, the use of jute in informal settlements infested with pests caused these to destroy the roofs.
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Thus, this model won't work for pest-infested areas or will have to be repeated every year," said the report.
Under model 3, a layer each of tarpaulin, cardboard, bamboo and existing tin were used, and mercury was found to be three degrees less than the outdoor temperature.
According to the report, based on GIS mapping and Chintan's area of operation, five informal settlements were identified for the current study on heat-resilient housing for the urban poor.
This includes Bhalswa landfill, Nizamuddin Basti, Vivekananda Camp in Chanakyapuri, Hanuman Mazdoor Camp in RK Puram and Sihani in Ghaziabad.
"A team of Chintan and STS Global surveyed 484 people living in identified wastepicker settlements. 100% of the respondents reported facing health impacts due to heatwaves," said the report.
While 45% of the respondents reported fainting and nausea when exposed to heat, 32% complained about a constant sense of fatigue and weakness.
27% of people reported breathlessness and asthma, which intensified during the peak summer.
Bharati Chaturvedi, founder and director of Chintan, said up to 30% of people in an Indian city lived in informal settlements, and their experience with heat was more intense and needed to be addressed with more nuance. "We have to address their thermal comfort if we want cities to continue to be running and we want health equity," she said.
