Does white washing Paint the roof reduce heat?

white washing : It is generally believed that whitewashing Paint roof of a building causes sun heat to fall back on it which is  best way to reduce temperature but how effective is this method & its negative effects? What are?

Does white washing Paint the roof reduce heat?

Former UN United Nations Secretary General Ban Ki moon recently told the British news in an interview that it could drop to 30 degrees Celsius & indoor temperatures could drop to 7 degrees Celsius.

Paint white washing:  Where do these data come from & what research proves them correct?

Ban Ki moon was talking about an ongoing pilot project in Ahmedabad Gujarat India. In Ahmedabad summer temperature reaches 50 degrees Celsius.

Does white washing Paint the roof reduce heat?

Does white washing Paint the roof reduce heat?

white washing Paint :In 2017 more than 3,000 roofs across the city were painted with special white paint.

Ravi River City Housings Project  Pinjab

How can you keep your home cool without Air Conditioner

This is a roof cooling process that reduces the heat generated by sun so that  minimum heat reaches inside of  building.

White paint: As much heat as the building absorbs this process of cooling the roof also helps to reduce temperature by expelling that heat.

Project documents state that this reflective roof layer can reduce temperature of roof by 30 degrees Celsius while indoor temperature can be reduced by 3 to seven degrees.

2 to 5 degree drop in temperature white washing Paint

Anjali Jaiswal of US based Natural Resources Conservation Agency says after inspecting the Ahmedabad project It depends on the layout but the process of cooling the roof compared to normal homes can increase indoor temperature by 2 to 5 degrees. Helps to reduce to.

Also Read :

Ravi River City Housings Project  Pinjab

How can you keep your home cool without Air Conditioner

This is slightly lower than Ban Ki moon estimate but still significant.

Another pilot project in southern Indian state of Hyderabad has used a membrane sheet to cool the roof which has found the indoor temperature to be less than 2 degrees lower than  outside.

As far as the temperature drop to 30 degrees is concerned the Gujarat pilot project did not find any answer but such results have come to light in Berkeley laboratory in the US United States  of California.

Research has shown that up to 80% of the light from a white roof hits & returns & on hot summer days this roof can reduce the temperature by up to 31 degrees.

Of course  situation in California will be different from that in India. Metal asbestos and concrete are used in the construction of more than 60% of the roofs in which heat is present inside building despite the layer of white paint.

However pilot projects in Indian cities such as Ahmedabad & Hyderabad have-been successful.

This is not a new idea

So why aren't more and more city roofs being painted white? The idea is not new, white roofs and walls have been seen in southern Europe and North African countries for centuries.

New York City's 10 million square feet of roof was recently painted white.

Building codes have-been updated to promote cold roofs in places like California. This is considered an important way to save energy.

Cool roofs can also reduce your Ac air conditioning bill by up to 40%.

Low cost & savings too

An experiment in Bhopal found that sunlight reflecting paint can save up to 303 kW of energy in buildings with low altitudes.

According to one estimate if the roof cooling paint is applied to every roof around the world it is likely to reduce global carbon emissions.

The Berkeley Laboratory says a concrete roof that reflects sunlight can cool up to 24 gigatonnes of carbon dioxide.

It's like removing 300 million car vehicles from roads for 20 years. Definitely a low cost option especially 4 poor countries.