Clean Tech

How about a ‘cool roof’ to keep the heat away?

V Rishi Kumar | Updated on June 18, 2019 Published on June 18, 2019

Diagram of a classic colonial showing the ways where the heat is being lost through the construction through the walls, door and windows, roof, ground and exhaust or ventilation   -  valigursky

Cool roofs are designed with a variety of materials to reflect light rather than absorb it

If there’s one thing that’s going to keep rising, it is likely the temperature. Because of factors such as global warming and lopsided development, urban areas are sizzling under extreme heat.

People’s response has been to invest in air-conditioners and coolers. But urban planners are now looking towards another concept that is sustainable in the long run — cool roofs.

What exactly are cool roofs?

Cool roofs are designed such they reflect light rather than absorb it, unlike in the case of most roofs of conventional concrete houses. Depending on the choice of material, cool roofs can help lower indoor temperatures by 2-5 degree centigrade, offering simple yet effective protection from extreme heat, says Rajkiran V Bilolikar, Associate Professor, Energy Area, Administrative Staff College of India (ASCI).

Typically, cool roofs could be a well-made tarpaulin sheet, a lime-based paint, a tiled rooftop, or a mosaic tile that reflects light, and so on.

The ASCI, the Natural Resources Defense Council, US, and the International Institute of Information Technology, Hyderabad, along with others, are collaborating to promote understanding of the concept of cool roofs, their importance to urban planning and how best to retrofit existing homes so that living conditions can be made more comfortable.

Rajkiran Bilolikar and Dr Vishal Garg of IIIT-H are now seeing acceptance gaining ground in Hyderabad city and Telangana as also Ahmedabad.

The Telangana government, in partnership with ASCI and others, has prepared a draft note on “Making Telangana a cool state with statewide cool roofs programme.” The note has been put up for circulation and after receiving feedback from various stakeholders, it will be approved and pave the way for the announcement of a cool roofs policy.

During a recent meet, Arvind Kumar, Principal Secretary, Telangana, outlined the State’s plan to make cool roofing mandatory in public buildings, schools, hospitals, offices and apartments. The move forms part of the Energy Conservation Building Code where all structures of more than 1,000 sq metres or built-up area of 2,000 sq metres would be covered under the cool roofing plan.

Hyderabad and Ahmedabad have taken up cool roof programmes with pilot initiatives. These will serve as models for others within the city and other regions of the country.

Telangana initiative

The general thinking on the cool roof initiative is that it will eventually fit well into the National Cooling Action Plan and various energy-efficiency programmes.

Citing a demo project, Bilolikar says the rooftop of a building was covered with tarpaulin supplied by DuPont. “During peak summer, the temperature was down by 3-5 degree C. This was also tried in several schools with a similar result,” he says.

The developing Smart City of Karimnagar has decided to take to cool roofs, initially with schools, and later follow it with regard to other buildings.

Telangana plans to take the lead in cool roof adoption by encouraging house owners as this will have a far-reaching impact on the city.

Air-conditioners guzzle power to bring down temperature in the interiors. With cool roofs, temperatures can be reduced overall without much investment.

The Telangana Cool Roofs Programme has been designed to increase the percentage of cool roofs, focussing on yearly targets by dovetailing with the Telangana Energy Conservation Building Code to increase savings on buildings and thereby reduce the urban heat island effect.

It is proposed to encourage people to use roof coatings, use pre-fabricated membranes or sheeting of polyvinyl chloride or bitumen-based special cooling roof material like cocunut husk and paper waste used in Gujarat and Delhi, as an alternative to RCC roof. Then there are green roofs of vegetation. However, this option is costlier as it requires water for maintenance.

As part of CSR

Arvind Kumar, Principal Secretary, Telangana, elaborates that the Government is implementing cool roof initiative in mission mode, seeking to encourage its adoption with the message that it helps reduce the temperature by 3-6 degree centigrade.

“We have been encouraging Government buildings, public institutions, commercial and residential buildings to adopt this, with the message that it pays back within a couple of years with the energy savings it brings.”

Efforts are on to connect with corporates to support this initiative under their CSR programmes, he says.

“We are also planning to rope in remote sensing agencies to assess the impact of the cool roof pilots,” adds Bilolikar.

Published on June 18, 2019

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