Tamil Nadu issues SOP for cool roof as pilot projects record drop in indoor temperatures

Published 6 June 2026 · india

After pilot projects in a city government school and a Perumbakkam housing complex showed that cool roof coatings could lower indoor temperatures by up to

After pilot projects in a city government school and a Perumbakkam housing complex showed that cool roof coatings could lower indoor temperatures by up to 5°C during peak summer, the Tamil Nadu government on Thursday (June 4, 2026) released a State-level standard operating procedure (SOP) to scale up the intervention across homes, schools, and public buildings. Launched on June 5, marking World Environment Day, the SOP is intended to standardise the implementation of cool roof coatings, which is a passive cooling measure that reflects solar radiation and reduces heat absorption by building surfaces. The document was released by Environment and Climate Change Minister V.K. Rajeev and Forests Minister R.V. Ranjithkumar.

Developed by the Tamil Nadu Green Climate Company (TNGCC) and the Tamil Nadu Climate Change Mission (TNCCM) in collaboration with the United Nations Environment Programme (UNEP) and Seeds Technical Services, the SOP lays down procedures for roof assessment, surface preparation, coating application, quality control, safety, and maintenance. According to the government, a pilot project at the Perunthalaivar Kamarajar Government Girls Higher Secondary School in Ambattur reportedly reduced classroom temperatures from around 31-32°C to 26-28°C. Indoor air and ceiling surface temperatures fell by about 4°C to 5°C, helping classrooms remain within acceptable thermal comfort levels during school hours, the SOP says. The SOP also cites a pilot intervention at the resettlement site in Perumbakkam, where cool roof coatings were applied over about 1,000 sq.

m of roof area covering 120 housing units. The project recorded roof surface temperatures that were 6°C to 8°C lower than conventional roofs and indoor temperatures that were lower by 4°C to 5°C during peak summer months. Officials said the Perumbakkam intervention also resulted in a 20% reduction in cooling energy demand and nearly 30% fewer thermal discomfort hours. Reducing AC dependence The SOP says that roofs are among the largest contributors to indoor heat gain in hot and humid regions and that reflective coatings can significantly improve thermal comfort while reducing dependence on air-conditioning and other mechanical cooling systems. The document prescribes a 12-stage implementation framework covering feasibility assessment, material procurement, roof preparation, patch testing, primer application, coating, quality assurance, and periodic maintenance.