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Painting The World's Roofs White Could Slow Climate Change
Hugh Pickens writes "Dr. Steven Chu, the Nobel prize-winning physicist appointed by President Obama as Energy Secretary, wants to paint the world white. Chu said at the opening of the St James's Palace Nobel Laureate Symposium that by lightening paved surfaces and roofs to the color of cement, it would be possible to cut carbon emissions by as much as taking all the world's cars off the roads for 11 years. Pale surfaces reflect up to 80 percent of the sunlight that falls on them, compared with about 20 percent for dark ones, which is why roofs and walls in hot countries are often whitewashed." (Continues, below.)
"An increase in pale surfaces would help to contain climate change both by reflecting more solar radiation into space and by reducing the amount of energy needed to keep buildings cool by air-conditioning. Since 2005 California has required all flat roofs on commercial buildings to be white and Georgia and Florida give incentives to owners who install white or light-colored roofs. Put another way, boosting how much urban rooftops reflect would be a one-time carbon-offset equivalent to preventing 44 billion tons of CO2 from entering the atmosphere. 'For the first time, we're equating the value of reflective roof surfaces and CO2 reduction,' says Dr. Hashem Akbari. 'This does not make the problem of global warming go away. But we can buy ourselves some time.'"
Let's also paint all the Grizzly bears white. That will address the problem of disappearing polar bears.
and make all the birds blind. we had a man in the neighborhood who had a white roof and it was filled with dead birds. birds fly towards white objects for some reason as if it's the sky, and splatter to death.
From TFS:
that by lightening paved surfaces and roofs to the color of cement
Personally, I wouldn't want to drive on a surface that bright; I'd be squinting even with my sunglasses on!
Also, as a current resident of California, I can see the value in having a light-colored car or house, but as a former resident of New Hampshire, I can tell you that having a black car and black roof on a cold but sunny winter's day is very helpful! Snow slides off my car roof with ease, and it means I didn't have to turn the heat up quite so much!
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Also, where is all this paint coming from? What are the environmental and economic impacts of making all of this paint?
Although this would reduce the amount of energy used for cooling, heating costs would go up. For most people, it takes far more energy to heat a house than cool it. It takes 1200 KWh to cool a house in a temperate climate for a year, but it takes 12000 KWh to heat one . It is more useful to look for ways to heat a house more efficiently than cool it.
and sea levels, but not for the pH balance of the oceans, which are acidifying as they absorb additional carbon from the atmosphere.
I remember reading about green roofs (growing plants etc on the roof of buildings) and the effect it had on temperatures when done in urban environments:
Reduce heating (by adding mass and thermal resistance value) and cooling (by evaporative cooling) loads on a building â" especially if it is glassed in so as to act as a terrarium and passive solar heat reservoir â" a concentration of green roofs in an urban area can even reduce the city's average temperatures during the summer.
The Fairmont Hotel, here in Vancouver BC does this, growing herbs for the hotel kitchens.
In the winter, a dark, hot roof doesn't heat a house very effectively (heat rising and all that- plus there's less incident solar energy).
In the summer, there's a lots of solar energy hitting your roof; and a hot roof leads to a hot attic, which retards flow of heat/hot air in the house (heat rising and all that).
So, a light-colored roof has a much more profound impact on cooling than on heating.
A metal roof will help both heating and cooling- and snow slides off them- but they are not cheap!
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Believe it or not, there is a lot of research going into creating lighter colored surfaces for roads. One of the advantages is that it takes less light (and thus energy) to light up the surface at night. This also decreases the amount of "light pollution" you would have around town. There are other advantages to improving water quality and decreasing noise.
http://www.eoearth.org/article/Cool_paving
However, one of the current hangups is how to keep them light? Unless we can also change the rubber in the tires to be lighter color as well, the road surfaces just end up black again in high traffic areas like California.
In New England, we have four seasons:
Almost Winter, Winter, Still Winter, and Construction.
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In Florida, we have only one season:
#RandomWeatherPattern
In California we have 3 seasons: Spring, Rain and Fire.
A house built to with heat conservation in mind should almost heat itself. I've moved into a new flat building in the UK, between all the insulation and double glazing its actually hard for me to get the flat cooler than 21 degrees.
During the winter when it reached -8 degrees outside, my flat without any heating was at 16 degrees. My neighbours have the same issue, we only have the one small flat below us so the heat isn't coming from downstairs.
I can think of several other new buildings which suffer from this problem. If your going to argue about the color of a building mandating improved heat conservation should remove most of the heating costs.
In Canada we have two seasons: winter and what they call winter in New England.
There is a tipping point to the cement argument which is why you don't see it in truly cold locations like Canada. Cement roads have a longer lifespan than asphalt and it works out to be cheaper in some locations. In other locations ,due frost, the ground moves too much to see the return on investment. In Canada where there is heavy frost every winter a cement road would still be required to be repaired every year but at a much greater cost due to the cracks caused by frost. This is why you see more cement roads in the southern states and less in the northern. Asphalt's lower cost to install and repair makes it a better fit in colder areas. Neither is a perfect solution but each serves it's purpose in it's place. The perfect solution, as always, is to give us our flying cars.
This signature would be better if I was creative.
Not just quick dry... All cement is an exothermic reaction. And would people SERIOUSLY stop calling concrete cement. Roads are made of concrete, which is a mixture of cement, aggregate, and water. Cement is only the binder of the mix.
Yes it's an anecdote! Were you expecting original research in a Slashdot comment?
I love all these Concrete examples.