Co-authored with Prima Madan
As the summer season kicks in, communities in India are already experiencing extreme heat. Keeping cool is once again a major priority for the country. The demand for cooling is growing, as highlighted by the Indian government’s recently released India Cooling Action Plan. One of the key solutions to keeping cool while saving energy is adopting cool roofs. The cities of Hyderabad and Ahmedabad, two of India’s fast-growing cities, are ramping up efforts with expanded cool roof programs this month.
Cool roofs reflect sunlight and absorb less heat. Depending on the setting, cool roofs can help keep indoor temperatures lower by 2 to 5°C (3.6 - 9°F) as compared to traditional roofs. Costs can be as little as ₹0.5 (~$0.07) per square foot for a simple lime-based paint, to more expensive reflective coatings or membranes. Cool roofs are designed to lower energy demand by using white materials on rooftops to reflect rather than absorb sunlight, minimizing heat absorption and allowing the buildings to be passively cooled rather than relying on air conditioning. When used on a large scale, cool roofs can reduce the urban heat-island effect.
Currently, less than 10% of India’s households have air conditioning units, while more than 60% of urban roofs are made from metal, asbestos, and concrete—trapping heat inside buildings. As living standards rise and more extreme heat becomes more common, demand for cooling and air conditioning will rise dramatically and can strain electric grids, worsen air pollution, increase fuel imports, and fuel climate change.
Hyderabad and Telangana Cool Roof Program
Telangana, and its leading city Hyderabad, home of a rapidly growing IT sector, is rolling out a cool roof program for the entire state. Hyderabad, the state capital, is one of the fastest growing cities in India. With a population of about 9.1 million (2011, Census), it is the sixth most populous urban agglomeration in India.
The Telangana region is in the hot and arid Deccan Plateau, and a rising population and skyrocketing urbanization increase both energy demand and the urban heat island effect. As Telangana works to improve living and housing conditions, cool roofs provide a crucial opportunity to advance human health and comfort. Particularly for low income communities, cool roofs provide increased thermal comfort that leads to improved productivity, especially for homes in slum communities.
The Telangana cool roofs pilot program is led by the Municipal Administration and Urban Development (MAUD) department and has three specific areas
- mandatory cool roofing in government and commercial buildings,
- voluntary cool roofing for residential and smaller buildings, and
- cool roofing for all low-income housing with reference to the Heat Action Plan
The Draft Telangana Cool Roof Program by the state has been put out for public comments and is available here.
The Draft Telangana Cool Roofs Program builds on a pilot program conducted in Hyderabad in 2017. As part of the state building energy efficiency program, the Greater Hyderabad Municipal Corporation partnered with the Administrative Staff College of India (ASCI), International Information Institute for Technology- Hyderabad (IIIT-H), and NRDC to implement a cool roofs pilot in low-income neighborhoods to showcase the benefits and impact of cool roofs in the city. The cool roof pilot project focused on a set of 25 low-income households. Dupont India supplied a high-density polyethylene (HDPE) cool roof coating membrane called Tyvek for the pilot as a part of their corporate social responsibility efforts that retails in Hyderabad for ₹13/square foot ($0.2/square foot). The results found that indoor air temperatures were observed to be lower by an average of 2°C (3.6°F) in the homes with cool roofs as compared to similar homes without cool roofs. The resident feedback survey found that 76% of the trial group residents expressed satisfaction with the cool roofs—and some of their neighbors applied makeshift cool roof membranes to replicate the success.
Read Part II of this blog series on the Ahmedabad Cool Roof Program here.
Prima Madan leads NRDC's India cool roofs work based in New Delhi.