Cool Roofs, Hot Cities: A Climate Solution Above Our Heads

Prof. Vishal Garg is Director of the Indorama Ventures Center for Clean Energy at Plaksha University.

India is in the grip of an extraordinary heatwave. In recent weeks, all fifty of the world’s hottest cities were located within our borders. Balangir touched 45°C, while Chandrapur, Prayagraj, and dozens of cities across Uttar Pradesh, Odisha, Bihar, and Vidarbha crossed 44°C — many of them before noon. Prime Minister Modi has called for a “Whole-of-Nation” response. The question is: where do we begin?

The answer, quite literally, is above our heads.

Tens of millions of Indians living in informal settlements are sheltered by nothing more than thin metal sheets, asbestos, or plastic covers. Through the day, these materials absorb and accumulate solar radiation. Through the night, they release it indoors. There is no insulation, no mechanical cooling, no reprieve. Research documents indoor temperatures in such settlements regularly reaching 40°C during peak summer; conditions under which sleep is disrupted, cognitive function declines, and the risk of heat-related illness rises sharply. For the elderly trying to rest, children trying to learn, and daily wage workers trying to recover, these homes offer little protection from the heat outside.

This is not a problem of individual summer days. It is a chronic seasonal health burden, and it falls heaviest on those least able to bear it. Reducing indoor heat exposure must become a central component of India’s climate adaptation strategy. The roof is where that strategy can begin.

The science is well-established. High-albedo – or reflective – roof surfaces reflect a large portion of incoming solar radiation rather than absorbing it, significantly reducing heat transfer into the living space below. Unlike mechanical cooling, this requires no energy input and imposes no burden on an already strained power grid. Field studies in India have found that white reflective roof covers reduced roof surface temperatures by more than 20°C and lowered indoor temperatures by 2–3°C during peak summer conditions. In a home already at 35°C and above, a reduction of this magnitude translates into measurably better sleep, lower physiological heat stress, and meaningful improvements in the health and productivity of those living beneath it.

Few climate adaptation interventions combine the attributes of being inexpensive, immediately deployable, energy-free, and capable of reaching thousands of households within a single summer. Cool roofs are among that rare category — and they deserve a central place in India’s national heat resilience strategy, alongside improved housing, green urban infrastructure, and building codes that mandate thermal performance for low-income construction.

A white tarpaulin sheet – widely available at hardware stores across India – can deliver this benefit for an entire household. It demands minimal maintenance and no technical expertise to install. And its utility is not confined to summer: the same waterproof sheet that reflects solar radiation in May and June reduces water seepage and protects the home through the monsoon. One intervention. Two seasons of protection. Years of benefit.

But policy and infrastructure take time. The crisis is now.

India has a long tradition of organised seasonal solidarity. Every winter, communities distribute blankets to those without adequate shelter. Every summer, volunteers establish water distribution points for those labouring outdoors. These acts of collective care are not small gestures – they reflect a civic instinct to protect the vulnerable, and they save lives.

This summer, that instinct can take a new form. Individuals, resident welfare associations, corporations, and civil society organisations can take one practical step: procure white tarpaulin sheets and donate them to households in informal settlements. The evidence for its effectiveness exists. The material is accessible. What is needed now is the will to act.

Heat resilience will ultimately require better housing, greener cities, and stronger building standards. But sound policy does not defer immediate, evidence-based relief while awaiting structural change. The most durable solutions and the most urgent ones need not compete – they can, and must, coexist.

As India adapts to a hotter future, some of the most effective climate solutions will not be found in distant technologies or future infrastructure. They are available today, affordable today, and waiting above our heads.