In the last few years, Sahani Begum found that the desert cooler she owned was barely effective enough. Her small, two-storeyed home in RK Puram’s Hanuman Labour Basti in New Delhi would become unbearable in the summers, the temperature inside rising much higher than outside.
Then, her son heard about a quick and simple solution through the internet – painting their roof white. Studies have found that applying reflective white paint on cemented roofs can reflect between 30% and 70% of direct sunlight, significantly reducing indoor temperatures.
Begum’s son bought the paint and finished painting two coats on the roof in a single day. They felt the difference immediately. “We could sleep in relief,” Begum, who is in her fifties, told Scroll.
As heatwaves become more frequent and intense in India, experts say it is no longer enough to simply avoid direct exposure to the sun – even indoor heat poses a risk to human health.
In fact, during summers, depending on the material used for construction, temperatures inside buildings can be as much as 12 degrees Celsius higher than outside, said Bharati Chaturvedi, director at Chintan, a non-profit that works on waste management and livelihoods.
In Delhi, low-income communities that cannot afford air-conditioning are experimenting with small-scale, low-cost solutions like the one that Begum’s family tried. City-level heat action plans have also recommended these – the 2024-’25 Delhi heat action plan recommends a “pilot project on roof painting with white color – cool roof and or distribution of gunny bags for putting on the tin roofs/asbestos in slums”.
However, while these affordable solutions are attractive, they face considerable challenges on the ground. Begum’s family, for instance, has struggled to continue painting their roof year after year.
A year after the family first did the job in 2023, Begum noticed that the paint had chipped off at places and needed a redoing. The NGO Chintan helped her household along with 39 others in the basti to complete the work. The organisation took care of all associated costs – they bought the paint and paid workers to do the painting.
This year, however, the project ended. Begum’s family will have to incur their own expenses to repaint the now chipped roof once more – she explained that the cost could go up to Rs 3,000.
“It’s not going to be possible,” she said.
Indeed, experts working on interventions like these are concerned about whether they can be scaled, considering that they can be expensive or do not last long. Indeed, as a report by Chintan found, in the around 200 houses they had introduced the intervention in, “not even a single painted cool roof” was “almost fully white, as initially applied” after a year.
“Painting white roofs does not work for everybody,” said Vinita Rodrigues, a project manager at Fair Conditioning, a Mumbai-based organisation that works on thermal comfort across five cities including Delhi.
In fact, Rodrigues explained, many solutions that focus on roofs are not even feasible to attempt given that families do not always find it easy to use the area.
In some places, their team found high-voltage wires in close proximity to roofs, which would make it unsafe for home owners to carry out any kind of work on them, while in other places, goats would venture on the roofs, and damage structures that had been installed to help tackle the problem of heat.
Rodrigues added, “A diversity of solutions has to be accessible to people. We cannot have a one-size fits-all approach.”
A range of problems
Other experts agreed that proposed solutions had to take into account a range of conditions on the ground. Thus, apart from concerns of cost and availability of material, “practicality of the interventions also becomes a factor”, said Manu Gupta, co-founder of SEEDS, an organisation that works on improving disaster resilience among communities.
For instance, Anshu, another resident of Hanuman Basti, found that painting her home’s roof white was ineffective because it was made of tin. “Compared to other cemented roofs, the cooling effect was not as much since the tin captures a lot of heat,” she said.
Another practical problem that many residents faced was that they used their roofs for a variety of purposes, limiting the space available to do any kind of work, and the effects of solutions such as painting. “Most of the people here sell scrap for work,” said Anshu, pointing to several roofs we could see around, which were covered with material such as cardboard, paper, glass, metal and plastic. “For them, the roof is an important storage space and many continue keeping their material.”
Close to the Bhalswa landfill in north Delhi, residents faced a more unpredictable hurdle while experimenting with a solution. With Chintan’s support, they had used large plastic bottles filled with water on roofs: the water’s ability to absorb large amounts of heat created a thermal mass, which helped lower the temperature inside buildings by as much as 3 degrees Celsius compared to the outdoors. However, many residents found that after a few months, the bottles began to be stolen for their high resale value.
To ensure that solutions provided are effective for specific kinds of houses, Fair Conditioning carries out “house audits”, which help them to understand “if structurally, a certain solution works for a certain type of home”, said Rodrigues. These audits document information like the age of houses and water availability.
The problem of affordability
As in Begum’s case, many proposed solutions are also unaffordable to communities.
For instance, Rodrigues explained, in situations where people use roofs for other purposes, experts have recommended working with other materials, which can be used under the roof to cool the home. Among these is alufoil, an industrially made material, which can be layered indoors, on the ceiling of a house, to trap heat. “But we found that this was an expensive material and so we have been looking for alternatives to this,” said Rodrigues.
One replacement they have been experimenting with is multi-layered plastic, such as the kind used on the silver side of packets of chips. “We have found it to be quite effective,” she added.
But communities told Rodrigues and her team about another problem that they encountered when they tried this solution – rat infestation. “Somehow, rats were finding a way to enter the sheets we had installed,” she said. “And now we are looking for ways to block their entries.”
Rodrigues explained that the most effective solutions to the problem of heat were “dynamic solutions”. She was referring to designs such as one involving a chain and sprocket mechanism, which rotates installed panels so that they can be positioned horizontally in the morning to block heat, and vertically in the evening to release trapped heat. This can reduce the indoor temperatures by 2 degrees Celsius.
“But the problem is that since there is a lot of metal in this design, these are expensive,” she said. “So our design team is currently working to find local alternatives to replace this as well.”
The report by Chintan also pointed out another aspect of the chain and sprocket solution that increased its costs. “Chain sprockets need constant greasing to work which may not be sustainable in the long run and incur additional costs,” the report stated.
Anshu noted that even a cheaper solution such as painting roofs was unlikely to catch on since most families in her locality did not own their houses. “Anyway I live on rent. Why would I want to spend this much money on a house which is not even mine?” she said.
Some organisations have tried tapping into existing government policies and grants to fund such work. “In Pune, we found that communities in low-income areas are eligible for housing repair grants every year through the city administration,” said Gupta.
Involving communities to ensure durability
Many experts believe that involving people in projects from the time they are initiated can inculcate a sense of ownership over them, and thus increase the likelihood that communities will carry work forward even without the support of NGOs.
SEEDS’ Gupta explained that they constantly received a “live feed” from communities about their experiences. “In one experiment, we had used cow dung and mud as a binding material on a bamboo frame,” he said. After households began using it, “people told us that it smells. We had not thought of it,” he said.
The best solutions, Gupta added, came from “codesigning with communities”, which would involve “negotiations of cultural nuances” and soliciting their active participation in the work.
Fair Conditioning conducts “listening workshops” that encourage communities to be involved right from the designing of a solution. “Our approach is that the communities know their homes the best,” Rodrigues explained. “And having these discussions ensures that a certain type of solution works for a certain type of home.”
