Tamil Nadu’s ‘Cool Roof’ initiative has found mention in a recent United Nations (UN) report as an innovation that helps in countering climate change in urban settings. The global body is also working on replicating such cool roof technologies in the national capital Delhi, the report notes. 

As part of the Urban Heat Mitigation Project, the Environment and Climate Change Department, of TN govt in collaboration with the UN Environment Programme, had implemented a cool roof technology in a residential area of Chennai. A recent note by UNEP on passive cooling solutions notes that this intervention led to a temperature reduction of 5 to 8°C inside the buildings during peak summer months.

Explaining the said cool roof project, Supriya Sahu, Secretary of Environment, Climate Change and Forests Department, TN govt, said in a post on X that the Lighthouse Project site in Perumbakkam was chosen as the pilot location. “Silka cool roof paint, with a high Solar Reflective Index (SRI) of 102, was applied to two residential blocks comprising 200 houses. This passive cooling intervention led to a temperature reduction of 5 to 8°C inside the buildings during peak summer months. We are now scaling up the initiative,” she said.

The UN report says that Chennai’s positioning as a major industrial and high-rise buildings and shortage of green space make it prone to punishing heat waves. “To reduce this so-called heat-island effect, UNEP’s Cool Coalition and India’s CEPT University mapped the city’s hottest areas and provided [state] officials with recommendations on how to use nature and passive cooling to bring down temperatures,” the report said. “These recommendations are being integrated into Chennai’s master plan and can reduce urban heat by up to 4°C and cut heat-caused illnesses by 15-30 per cent,” it adds. 

Financing mechanisms

UNEP is also partnering with several agencies in TN to develop financing mechanisms to support the integration of passive cooling into government-supplied social housing. 

Passive cooling solutions ranging from reflective roofs to cool pavements to shade-providing tree cover are cited as a few ways cities can tackle rising heat. “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,” the report said. 

It also cites other examples in India wherein UNEP’s interventions along with other stakeholders has helped beat the heat. 

To help give commuters relief from the heat in Delhi, the UNEP-led Cool Coalition in partnership with national and local government bodies is also installing a “cool roof” on the 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,” UN notes.

UNEP is also helping Pradhan Mantri Awas Yojana–Urban (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.

Published on June 14, 2025