Scientists at the Lawrence Berkeley National Laboratory in California have suggested a plan to drastically reduce global warming, by painting the world white. If implemented successfully, it would be the equivalent of taking the world’s 600 million cars off the road for 18 years.
Hashem Akbari and Surabi Meno, along with Art Rosenfeld, California Energy Commissioner and Professor Emeritus at the University of California, Berkeley, are so convinced that their idea will work, that they have proposed a “Cool World” plan that would use white roofs, and solar-reflective roofs of other colors, to reduce greenhouse gas emissions and help delay atmospheric heating effects.
The team reckon that current flat roofs only relect 10-20% of solar energy, absorbing much of the remainder to heat up the buildings they cover. Cities also heat up far more than the countryside because of their dark roofs, dark pavements, and the absence of vegetation – an urban “heat-island” effect that raises the average air temperature of cities and their suburbs.
In a paper to be published in the journal Climatic Change, the team estimate that if buildings and streets in the world’s urban areas are re-fitted with “cool” materials, which reflect more sunlight than conventional materials, it could offset the global-warming effects of 44 billion metric tons of CO2 emissions.
I love low-tech solutions like this and, although it might sound faintly off-the-wall, the idea seems so simple that it couldn’t hurt to experiment with it on a small-scale to measure the projected effects. Now where’s that white paint…
Image Credit – tomsaint11 via flickr on a Creative Commons license
[...] PlanetSave.com: Hashem Akbari and Surabi Meno, along with Art Rosenfeld, California Energy Commissioner and [...]
As someone who is now into his 2nd Summer (in central NJ) with a completely bright, white roof, I can personally report that it works like a dream in keeping my single family ranch house cooler and saving money on my central AC bill while not raising my Winter heating costs at all. As William correctly pointed out, attics are supposed to be insulated from the living space below and are ventilated so that they are very hot in Summer (with traditional roofing materials) and very cold in Winter. In my particular case, the central air ductwork runs throughout the attic and this is where the problem comes from in the hot weather, even with the attic exhaust fan going all the time. Before coating my roof white, the central AC could not offset the extreme attic temps (120F-125F) surrounding the ductwork nor the afternoon effects of the all day heat “sinking into” the house from the ceilngs. The central AC ran almost all the time and we still needed a window AC unit in the bedroom to be able to sleep comfortably at night. Not any more. No more window AC unit and the average attic temp is a good 20F-30F lower, even on the hottest of days. And the central air no longer runs all the time.
I did the entire job of coating my roof with white elastomeric compound myself (2 coats) for about $600, using BlackJack Roof-Gard 700 (7-yr.) (a bit less expensive than Kool-Seal and just as good a product, imho). It worked so well on the house, that I also coated the roofs of my (un-insulated) garage and shed. Now I can work inside them for more than 10 minutes on hot days without collapsing, so significant is the inside temp. reduction.
Imagine the energy and money saving benefits if all black tar commercial building and apt. building roofs were coated white…
So laugh all you want to Randy, Steven, Lucas and who-all else. I know from first hand experience that I’m more comfortable in my house now and am saving money to boot since I coated my roof white!
Randy … Most attics are cold in the winter. They are ventilated. The heat gained by the sun heating the roof isn’t actually recongnized into the living space. … You say people should think things through? White roofs were recommended by Steven Chu, Chief of the EPA and a Nobel prize winning physicist. I’m sure he is better able than you or I to think things of this nature through.
I’m sorry but all I can do is laugh at all of you, this idea, and the idiot Obama! You are all just to funny!
this is so ridiculous. what about winter when the heating costs will skyrocket? summer isn’t the only season in most of the world. people should really think things through. and just a few hundred years ago greenland was green and nordic people had crops growing in what is now ice. we are not even close to the warmest periods in recorded history, not even in the last 100 years. people get the real facts before you start this silliness
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 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?
When did the word “scientist” become synonymous with the word “idiot?”
I very much appreciate the simplicity of the solution, and the cost is negligible when you consider that most rooves have to be SM colour – why not choose white when it comes up next – be it replacement or repair or maintenance.
As for chastising President Obama for his greenhouse footprint – very petty. As a public figure – and he certainly is now – he has an obligation to be where he is most useful – and if not Philadelpia it would have been somewhere else.
If you really want to make an impact on carbon emissions – petition your Senator to outlaw all playing of sporting events under lights, and all forms of motor sports – whether it be cars, bikes, boats or aeroplanes using any combustible fuel.
I’ll give you London to a brick that you won’t write the letter, because you want the Superbowl and you want the Indy 500 – so who is not green?.
What’s it matter man. That frickin’ Obama betrayed all of us this weekend. He flew to Philadelphia and then jumped on a train only to head back to DC. Do you understand how big his carbon footprint was this weekend? Obama isn’t green. He betrayed us. Now we have to live with the realities he is selfish and doesn’t care about the planet. Damn him! Doesn’t he know the arctic ice is melting and he has to put on a show like this weekends?
This has been getting a fair amount of play lately as one of those solutions that was known for years but rarely promoted. Just think if this had become a national priority thirty years ago when we knew that a limited supply of fossil fuel was going to cause us problems down the road.
As with many solutions, it works better in some places rather than others, which simply means we should move fastest in those areas with the greatest ROI!
It’s a little more than just painting a roof to get it white and not a real cheap solution for the building owner. Generally, it will cost an owner about $2.50 to $3.00 per sq. ft. to properly coat the roof white. So, if you look at a 50,000 sq. ft. facility it wall cost around $150,000. Now, if the building is in the southern 1/2 of the US and is air conditioned, they can pay for the roof very quickly in energy savings. In a lot of those states, Florida for example, give huge rebates to the building owner if they install a white, Energy Star certified, roof. Some as much as 20% of the total bill. I think this would be a great way for the US to, first off all, create jobs, in the way of roof restoration companies. Lowering energy costs for the summer months in hotter climates. A national rebate program to entice the building owners could possibly be a good thing.