With each passing year, hundreds of millions of Indians eye the approach of summer with trepidation. This year, the thermometer climbed above 40C in many places in late April, earlier than normal.
The impact of heat in India has been severe in recent years, with numerous heat-related deaths, widespread reports of heatstroke and school closures reported.
Even if nations start bringing down the greenhouse gas emissions warming the planet, temperature extremes are here to stay for the foreseeable future, said Balakrishna Pisupati, who leads the United Nations Environment Programmes (UNEP) India office. Facing the kind of oppressive heat we have seen, people across this country will need to adapt, especially in ways that dont worsen the climate crisis.
This, says Pisupati, is where passive cooling solutions come in.
Passive cooling solutions range from reflective roofs to cool pavements to shade-providing tree cover. Crucially, and unlike air conditioning, these solutions dont spew out planet-warming greenhouse gas emissions nor enflame the climate crisis.
India has emerged as a global champion of passive cooling, integrating these approaches into national policies and city planning, often with the support of UNEP. Heres a look at a few examples.
Cooling Delhis rooftops
The Indian capital of Delhi is one of the hottest major cities on the planet, with temperatures reportedly feeling like 50C with humidity earlier this month. To help give commuters relief from the heat, the UNEP-led Cool Coalition in partnership with national and local government bodies are installing a cool roof on the bustling Kashmere Gate interstate bus terminal. The roof, which covers nearly 150,000 square feet, will be retrofitted with a surface that reflects at least 80 percent of solar heat, helping to cool upwards of 100,000 commuters daily.
The project, supported by the Swiss Agency for Development and Cooperation, is part of a larger effort by the government and the UNEP-led Cool Coalition to blunt the effects of heat waves on Delhi and protect the citys most-vulnerable residents.
Lowering the temperature in social housing
Pradhan Mantri Awas YojanaUrban (PMAY) is Indias flagship affordable housing scheme; to date, it has provided safe, secure homes to millions of families. However, in many affordable housing projects across India, keeping cool remains a challenge.
UNEP is helping PMAY to integrate passive cooling features such as natural ventilation and insulated walls into the 10 million homes the government targets for delivery by 2029. These efforts could reduce electricity use by up to 35 per cent, by lowering indoor temperature by 3C and giving families 40 per cent more time in the year without needing cooling.
Thats part of a broader UNEP effort to reduce the heat in low-income neighborhoods. UNEP is also partnering with several agencies in the state of Tamil Nadu to develop financing mechanisms that would support the integration of passive cooling into government-supplied social housing.
Heat-proofing Chennai
Located in southern India, Chennai is a major industrial hub prone to punishing heat waves that typically sweep through ahead of the annual monsoon. Home to over 12 million people, Chennais dense population, high-rise buildings and shortage of green space are causing temperatures to spike. To reduce this so-called heat-island effect, UNEPs Cool Coalition and Indias CEPT University mapped the citys hottest areas and provided officials with recommendations on how to use nature and passive cooling to bring down temperatures. These recommendations are being integrated into Chennais master plan and can reduce urban heat by up to 4C and cut heat-caused illnesses by 15-30 per cent. The effort has been supported by the Swiss Agency for Development and Cooperation, the Government of Denmark, the Clean Cooling Collaborative initiative and the World Bank.
Bolstering national urban planning guidelines
In India, most cities dont take a standardized, scientific approach for mapping urban heat, which is essential to developing plans that address scorching temperatures.
To change this, UNEP and partners are supporting central and state government efforts in India to adopt cutting-edge strategies for identifying and addressing urban heat hotspots. UNEP is also advising authorities as they develop guidelines for how central and state-level agencies can use disaster-related funding on projects that reduce temperatures in urban areas, including through passive cooling.
In Tamil Nadu, for example, the state government declared heat as a disaster and with UNEP support, it has identified a range of passive cooling solutions for schools, factories and social housing.
