Bhubaneswar: The mercury has crossed 40 degrees Celcius and our roofs and walls are hotter than ever. Here are a few simple and uncomplicated ways to cool your home and also bring down the electricity bill.
How does it work?
Darker colours absorb more light and heat, while lighter colours reflect it away. White being the lightest colour, reflects up to 90 per cent of sunlight. While traditional black/grey roofs reflect only 20 per cent of sunlight according to whiteroofproject.org. Reflecting this heat away can keep interiors cooler by up to 15 degrees Celcius.
Known simply as “cool roofing”, this process is designed to reduce the solar radiation absorbed, which in turn means less heat is transferred inside the building.
How does it lower electricity bills?
By reducing the interior temperature, air conditioners need to work less to cool the room and consume less energy.
White roof options
1. Slaked Lime or choona (Lasts a season)
This is one of the most common techniques and also the most affordable option. Slaked Lime is mixed with adhesive (usually Fevicol) and applied on the roof. This, however, doesn’t last long when the rains come.
2. White cement paint (Lasts a year)
White cement paint lasts better than slaked lime and is quite affordable as well. It needs to be reapplied every year. This usually costs around Rs 2,000-3,000 for a 1,200 sqft roof.
3. Elastomeric Paints (Lasts around 5-7 years)
If you can invest a bit more, apply an elastomeric paint which will save you the labour cost in the long run. Dr Fixit Newcoat, Asian Paints Damp Proof, Xcel Coatings Roof Paint, Berger Roof Paint, etc are a few options available in the market. This paint can last around 5 years and is effective in waterproofing your roof and helping increase its life span. It costs around Rs 4,000 for a 600-700 sqft roof excluding labour charges.
4. Ceramic Tiles (Lasts almost a lifetime)
Tiles are a permanent solution and make your terrace more usable. White, glazed ones with a high reflective index can cool your roof throughout the year and also increase its longevity. It is important to use vitrified tiles with proper grouting else the tiles can break.
Cost: Rs 70 per sqft (starting price).
5. Green Roof
Another alternative is growing grass and plants on your rooftop. This will not only cool your interiors but also generate fresh air and makes the rooftop a great place to be. For this, one has to ensure that the roof structure can withstand the load and also waterproof your terrace properly.
6. Solar Panels
Solar panels can not only shade your roof but also generate electricity. This is the most expensive way but it pays off as it offsets your electricity bills and lasts 25 years at least. This is one of the best ways to reduce pollution.
Did you know white roofs are great for the environment?
A dark roof radiates heat in the evening and makes the surroundings hot. This heats up cities, and is known as the “urban heat island effect”. By painting the roof white, we can prevent this heat. According to Lawrence Berkeley National Laboratory in Berkeley, “White roofs cool the world, offset CO2, and delay global warming” by reflecting the heat back to space. It also reduces air conditioning bills by 20 per cent.
