This summer, cool it with white roofs

With Bengaluru’s temperature soaring this summer, residents are turning to paint their roofs white to escape the heat.

Jayanthi Venkatachalam, a homemaker in her late 40s, resident of Jeevanbheema Nagar got the roof of her house painted white recently.  Her husband, S V Venkatachalam, a scientist at ISRO, heard of painting roofs white as a method to keep buildings cool from a friend and decided to try it. She says, the rising mercury made life unbearable for her family as a fan was just not enough to provide relief. 

Jayanthi says they did not go for air-conditioners or air-coolers because of the cost in terms of buying one and also monthly electricity bills incurred in running them. Although it has only been a few days since they painted the roof white, Jayanthi says they are already feeling comfortable. "This change is obvious and our house is much cooler than before, we do not feel the need to go for air-conditioners or coolers with this," says Jayanthi.

A roof painting in progress in Banashankari. Pic courtesy: Lenin Sundarararajan

 

Painting roofs white is not a new idea for Ramesh Sivaram, 39, a Director of a food processing company. He painted the roof of his house, on Sarjapur Road almost five years ago. He used good quality exterior water-proof paint for his roof. He now needs to apply a single coat once in two to three years. "My house is at least a few degrees Centigrade cooler than before," says Sivaram.

There are many options for anyone interested in painting their roofs white. One can do a simple whitewash of the roof but it will have to done regularly as the rains might wash away the paint. The albedo levels of such paints might also be lower. Albedo is the scientific term that denotes the reflecting power of a surface.

A roof painting in progress at Jeevanbhima Nagar. Pic: Yograj S Mudalgi

Newer paints in the market claim to have been specifically designed with high albedo. Lenin Sundararajan, who runs LAKS Technologies, manufactures and distributors of paint called Sun Sheetal. He says it is can reflect up to 86 per cent of sun’s rays. Sun Sheetal can cost between Rs 20 – 25 per square feet including labour.

A Ali, of Karnataka Hardware and Paints in J P Nagar says Kool-n-Seal paint by Birla White used for painting roofs is one of their best selling products. The demand for the paint, says Ali, is so much that they are out of stock and are still waiting for arrival of new stock. "A 25-kg tub of the paint costs Rs 2300 and can cover an area of 30 – 35 square feet," says Ali.

Hiten Chavda, lead architect of Bio-diversity Conservation India Limited (BCIL) says that over 70% of heat in a building enters through the roof and is heated up quickly, especially by infra red and ultra violet rays of the sun. Building materials being good conductors of heat radiate this to the inside and trap it there. While the rest of the earth cools down after the suns sets, our homes are still warm inside. To combat this, Chavda says, roofs can be painted white as the colour reflects a large part of the sun’s rays back in to the atmosphere, thus reducing the heat absorbed by the building.

Temperatures, Chavda says, can differ by as much as 10 degree centigrade between painted and non-painted roofs. To get the best effect, he says, high albedo paint should be used. "High albedo paints are highly reflective and can reduce conductivity of heat considerably. In our buildings, we have found reduced energy consumption for cooling drop by as much as 20%," he says.

Temperature difference before and after painting the roof white. Pic: Yograj S Mudalgi

White roofs can even help reduce the ‘Heat island effect’ one of the causes for rising temperature in urban areas. Concrete structures and tarred roads not only heat the surroundings, they also trap it. So urban areas become islands of heat. But with white roofs, more heat is reflected back in to the atmosphere, cities can remain cooler.

Naresh Narasimhan, principal architect at Venkatraman Associates, an architectural firm based in Bangalore says it has been long since benefits of painting roofs white have been known. "Not only can they keep homes cooler, if all surfaces in the city are painted white, they will bring down the temperature of the area considerably," says Narasimhan.

Comments:

  1. A.Santharam says:

    There are two factors to be known before we select a particular heat radiating paint. One is the specifications like whether it also does water proofing of roof and the quantified parameter of the reflecting capacity of the paint.It will be helpful if more information is given regarding the specifications. Second is the cost. Birla make kool-n-seal will cost 2300/30= 80 per sft where as Laks Tech paint costs 20-25 per sft(including labour) as per your article. Why is so much difference in cost ? Please help us to choose the right one. Thanks. A.santharam (Retd Scientist NAL), JP Nagar 3rd phase. Mob: 9448014685

  2. Yogaraj S Mudalgi says:

    Hi,

    I work for Citizen Matters and am the author of the article. The paint from LAKS Technologies is not intended as a sealant or a water-proofing agent. It is mainly for for reflecting sun light whereas the website for the Birla paint claims that it can be used for water proofing. One kg of birla paint can cover 30 sq feet so a tub of 25 kg can be used to paint 750 sq feet of roof area. However this does not include labour charge so that will be extra. Exact figures for reflecting capacity for the Birla paint is not available as the website does not list any but for Sun Sheetal it is 0.855 i.e., it can reflect close to 86% of the sun’s rays. I will verify the reason for difference in cost and get back to you by Monday at the latest.

  3. raghunath says:

    hi
    I vouch this concept we are are distributors of NASA approved paint which is ceramic based hence eco friendly. this has special property to cover up existing cracks apart from temperature resistance water proofing and fungal/algae growth resistance most useful for roof tops, operation theaters, water bodies etc with other host of benefits
    raghunath
    9538860043

  4. k n g rao says:

    Great news!! I think i will have white paint done to the roof.can some one throw more light on this ?
    1 what kind of paint?
    2 cost/sft
    3 life of such painting say 3/4 years effectively?

  5. raghunath says:

    hi
    it costs rs 60 for 3 coat of paint this is ceramic based paint and is designed to last for 10 years.
    raghu

  6. raghunath says:

    this includes every thing other than scaffolding charges if it is required. it is available in colors also but the effect will come down to some extent
    raghu

  7. raghunath says:

    when it comes to thickness of coating depending on absorption factor projected thickness is close to 250 microns for 3 coats put together each kg covers 50 sft and water is the diluent so it is totally eco friendly product.
    raghu

  8. Sun says:

    Hello,

    You say Rs.60 per sq ft, and three costs. Why we need three coats? Also what is the brand of paint you going to use?

    Thank You

    Sunder

  9. raghunath says:

    we need 3 coats to get required insulation crack filling crack resistance algae fungal growth resistance etc.
    raghu

  10. Lenin Sundararajan says:

    Dear Friends,
    This is Lenin Sundararajan, Owner of LAKS Technologies, Bangalore. When one talks of heat reflecting and water-proofing in the same length, it means that the thickness of coating should atleast be about 1 mm and the elongation of the coating should atleast be > 200%. But in case of heat reflecting/high albedo paints of any kind, the thickness of the paint is hardly 100 to 200 microns(o.1 mm to 0.2 mm). So heat reflection and water-proofing have looked at separately. Heat reflecting paints can only waterproof to the extent of hair-line cracks of less than an mm thickness. LS – 09900146499

  11. raghunath says:

    hi

    what you are mentioning may be true to the base of product and its formulation one handle there are special products which can deliver results
    raghu

  12. ddpo sbkolkolgpo says:

    NILANJAN,KOLKATA: hi can you please tell me whether we can walk on top of roof painted with cool roof paints or sort of that.

  13. Manohar Rao says:

    i got cool coating done on my roof last year with v good results ( i even avoided installing a/c) at lower costs than mentioned above – Ragu

  14. saroj panda says:

    Hi,

    I also want to be environment friendly “Go Green” and conserve Electricity.
    Which Heat Reflective Paint would be more effective with lower cost.

    Will Appreciate any suggestion on this.

    – Saroj Panda, Kasavanahalli, Bangalore

  15. Rajesh Pareek says:

    I live in Jodhpur, Rajasthan, known as Suncity of India, summer temp reaching upto 48C, I am planning for heat proofing my home’s roof (rcc), kindly suggest which cool coat paint is best & the cost of paint sqft & the availability of paint in Rajasthan. Thanks. Rajesh Pareek

  16. murrali says:

    Dear sir/madam I am murrali from india tamilnadu chennai.we are manufacturer roof cooling TILES high quality.100% heat readuces.long life guarantee sample available any size and colors.if you want please reply.contact:mobile: 09042281781..mail: mm1murrali@gmail.com

  17. murrali says:

    Dear sir/madam I am murrali from india tamilnadu chennai.we are manufacturer roof cooling TILES high quality.100% heat readuces.long life guarantee sample available any size and colors.if you want please reply.contact:mobile: 09042281781..mail: mm1murrali@gmail.com

  18. Star Shield says:

    Star Cool Shield & Star Water Shield are the revolutionary field proven Heat Reflective & Water Repellent paints.

    Star Cool shield has been certified as Highest Solar Reflective Value, SRI-125, in the country, tested by NABL Certified lab as per ASTM/LEEDS ​standards for green buildings.

    STAR COOL SHIELD is designed to reflects sunlight to a greater extent
    and prevents the roofing materials from getting heated up, even in
    peak summer afternoons. keeping the rooms cool and comfortable.

    STAR WATER SHIELD is designed to impart water repellency to wide
    variety of substrates. Incorporated with latest technology designed
    for prevention, repair and maintenance of the buildings.

    Visit: http://www.starshield.in
    Mob: 9910386387, 9999922246

  19. Teja Swaroop says:

    Hello,
    Can I apply heat reflective paint over asbestos roof for reducing the room temperature?
    Please help me in this regard.Thank u

  20. Lenin Sundararajan says:

    Hello Teja Swaroop,
    Greetings!
    The answer is a definite yes. In fact, the product helps in 2 ways –
    1. by preventing heat flow to the living space by way of reflecting almost 90% of the infra red rays – normally heat transfer is instantaneous in asbestos sheets unlike in RCC roofs (which stores heat and then releases the heat flux once temperature around subsides). This heat flow is completely prevented.
    2. By acting as an agent which encapsulates the asbestos sheet. The asbestos sheet releases asbestos dust when in contact UV rays. These asbestos particles are proven to be carcinogenic. To many of our customers I also recommend application of any kind of paint on the ceiling level so that people are not exposed to these carcinogenic materials.

    Thanks,

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