Jun
11
2007

White roofs reflect heat, leaving the structures below cooler: Photo by gadfly pro from Flickr.com
White roofs reflect heat, leaving the structures below cooler: Photo by gadfly pro from Flickr.com

Looking for an easy way to reduce global warming, and save yourself a few bucks in the process? Paint your roof white! Most rooftops in America are black or some other dark color. These absorb heat, making the building hotter and less comfortable. People in the building run fans and air conditioners to cool off. Not only do they spend more on energy, but the power companies have to burn coal and oil to produce the electricity.

But a white roof reflects heat. The building stays cooler, and needs less electricity.

For maximum effect, you should use special heat-reflective materials. And keep the roof clean – dust and dirt darken the roof, reducing its reflective properties.

It’s been estimated that if every roof in the world were white, it would counteract all the global warming of the last 30 years! Now, the authors of this study admit that they used a very simple model – climate is much more complicated than their equations allow – but still, like changing your lightbulbs, this seems like an easy way to start having an impact now. In California, the government is giving rebates to building owners who install cool roofs.

Your Comments, Thoughts, Questions, Ideas

Anonymous's picture
Anonymous says:

This is really interesting! I didn't knowthat doing something so simple could have such a big impact on things! (I personally don't beleive in Global Warming though)

posted on Tue, 06/12/2007 - 1:54pm
Code's picture
Code says:

I guess birds will soon having a hard time flying above our houses. I bet its gonna be very hot for them. I think I'm just thinking too much about it. Anyway, it's a very nice idea.

posted on Mon, 06/25/2007 - 5:24pm
Gene's picture
Gene says:

Here's an article from a couple years ago on the benefits of painting roofs and roads a lighter color, and planting more trees, all to lower urban temperatures.

posted on Sun, 07/01/2007 - 8:16am
Anonymous's picture
Anonymous says:

As one of the dangerous feed-back loops, is losing the albedo effects of the glaciers, ice caps etc., it surely makes sense to replace the reflective white ice/snow with white paint, in order to stop this loop! It's cheap, we will never know until we try and quite honestly too much is at stake. So stop discussing & get white washing. This needs to be done all over the world so it's going to take time as it is. All the cities, towns & villages of the world needs to be done, if it's to be effective. The next thing we could all do, is to plant trees and grow clover in your lawns. Clover is very effective at absorbing CO2 & good for bees and butterflies. The governments should implement the renewable technologies asap and ban all plastic bags. Who banned the electric car? Well we need them now asap! If the warming continues, we will have a lot more to worry about than ice caps melting. The methane lying at the bottom of the oceans will belch up from the deep & create gas clouds, then the permafrosts, which are already melting release their methane gas. Our air will become suffocating and dangerous. A simple spark would cause catastrophic fire storms, sea vessels on fire & with planes exploding, whole cities would be wiped out! If the tree loggers of the tropical forests knew this was certain to happen, I wonder if they would actually stop destroying the lungs of the world? Reforestation is what is urgently needed in these tropical areas. We also need as much of the land to be left wild as is possible. To do this we need the vertical farms which are under serious discussion right now. Amen

posted on Tue, 11/20/2007 - 10:03am
Gene's picture
Gene says:

Your suggestions are all very good ones. However:

No one "banned" the electric car. The early models simply didn't perform as well as ones with gas-powered motors. Even today, the best electric cars are more expensive, less powerful, and don't travel as far or as fast as gas-powered cars -- though that gap is closing. Electric cars may soon be good enough for most purposes.

Many scientists dismiss "disaster movie" scenarios for global warming. If the Earth continues to warm it will of course change, though almost certainly not in a cataclysmic fashion.

posted on Tue, 11/20/2007 - 11:35pm
Anonymous's picture
Anonymous says:

"Many scientists dismiss "disaster movie" scenarios for global warming."
Acutally, many scientist are starting to think that their predictions have been too conservative. While "disaster movie" scenarios are in no way guanenteed, very bad scenarios are more likely then previously thought. I suggest people watch wonderingmind42's videos such as "how it all ends" on youtube.

posted on Fri, 05/23/2008 - 3:04pm
Gene's picture
Gene says:

You got a citation for that? Here's a few with scientists saying that disaster is not imminent, or even particularly likely:

New York Times

New York Post

Newsweek (excerpt)

posted on Fri, 05/23/2008 - 5:13pm
Anonymous's picture
Anonymous says:

If we paint all the roof white in areas where it gets cold like below 0, it would take so much more energy to heat up a house. Yes it would be nice in the summer, but in winter we need the dark roofs to help heat our homes.

posted on Wed, 11/21/2007 - 10:52am
Anonymous's picture
Anonymous says:

In winter, you put on an extra layer if you are cold.

posted on Fri, 05/23/2008 - 3:06pm
Anonymous's picture
Anonymous says:

yes, everyone should do that because if you dont you have a very high chace at catching a nasty cold.

posted on Fri, 05/23/2008 - 3:48pm
Rosie Mae Powell's picture
Rosie Mae Powell says:

I think this is a dearly interesting subject. It sickens me that my parents will not paint the roof white. I strongly believe that the world would be a better place if all the roofs were white. It's a vital issue.

posted on Wed, 01/21/2009 - 6:55am
JGordon's picture
JGordon says:

Keep at them, Rosie. Ask your parents for a white roof every day, over and over again until they cave. They'll thank you for it someday.

posted on Wed, 01/21/2009 - 10:44am
wookiemeister's picture
wookiemeister says:

a quick explanation of why white paint works to cool the planet

1 around 50 percent of sunlight is visible light

2 around 50 percent of sunlight is heat

3 visible light is a frequency of light NOT absorbed by the atmosphere

4 some HEAT (infra red) from the sun IS absorbed by the atmosphere directly (greenhouse gasses which makes the atmosphere warmer).

5 HEAT from the sun also warms the surface of the planet and this HEAT is then radiated back into the atmosphere again being absorbed by greenhouse gasses.

6 visible light is poorly absorbed by the atmosphere, some of it gets reflected back by the atmosphere.

7 the visible light that doesn't get reflected back by the atmosphere is either reflected by the surface (eg a snow field) or absorbed by the surface (an asphalt carpark/ road). this absorbed light heats the dark surface. this heat is then radiated into the atmosphere and is absorbed by greenhouses gasses makiig the atmosphere warmer.

8 by painting your roof white and other surface you reflect around 50 percent of the visible energy from the sun, a significant amount of this is reflected back into space WITHOUT heating the atmosphere.

9 by painting enough roofs you make buildings cooler and cool the atmosphere. air conditionig works easier to cool houses because they are cooler, perhaps you wouldn't even need air conditioning?

if you are thinking of using white paint to cool your roof you will need a special white insulative paint that both reflects the visible frequencies of light and stops infra red frequencies from heating your roof.

posted on Fri, 04/03/2009 - 11:53pm

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