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There are a lot of smart people out there busy devising clever ways to help combat global warming — Bill Gates’ and his recent support of algae fuel research, for instance, not to mention yesterday’s announcement of the long-range electric Chevy Volt — but there are some very simple, low-tech steps that can be taken, as well.
It’s obvious why most roofs and roads are black: that’s the color of asphalt. But black absorbs heat while white reflects it, and according to a new study if the 100 largest cities in the world were to paint all their roofs white and switched to lighter-colored road materials, it would reflect enough light and heat back into space to offset all the global warming we’ve experienced in the last few decades. (Sounds crazy, I know — but consider this: a white roof in a warm climate can decrease air conditioning bills about 20%.)
Of course, people living in cold climates have a different set of challenges — and a black roof can be advantageous during chilly winters, when retaining heat is what’s important. Regardless of that distinction, however, it seems we should all be paying more attention to what color our roofs are.
Via Ecogeek.
Comments (13)
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It would seem to me that lighter colored road materials could be hazardous, i.e. too much glare to distract and blind drivers? I know I experience more glare issues on the interstate, where the road is lighter, than I do on darker surface streets.
posted by Lindsey on 9-18-2008 at 1:00 pm
There are concrete roads everywhere and if they were unsafe from people being blinded from… uh… the starkness of dull light grey, they wouldn’t build them.
posted by Byrd Brain on 9-18-2008 at 1:15 pm
Our company just had the roofs of 2 of our buildings (about 50,000 sq ft total) “foamed” in white. There is easily a 7 to 10 degree difference inside as a result. However, going up top to look at it almost burned my retinas off.
posted by erik on 9-18-2008 at 1:37 pm
Lighter colored roads also seem more dangerous to me; but of course, there are various colors that could be tried. As far as concrete roads- Is concrete a material that can be used for highways? I’ve seen many concrete roads in cities in low speed limit areas; is it durable enough for bigger roads? Is it already used for bigger roads? (That’s a real question that I’d be interested in hearing an answer to.)
Overall, this seems like a fantastic and relatively simpe way to make a big difference in the fight against global warming.
posted by ann on 9-18-2008 at 2:50 pm
I saw a video with a child inventor who’s idea was to have roofs that had a step build. The horizontal sides of the steps would be painted white to reflect sunlight when the sun was high in the sky (summer) and black on the vertical sides of the stairs to retain the heat (winter). Looked like a great idea, especially in temperate climates.
posted by Amy on 9-18-2008 at 3:01 pm
i had actually thought of this before. well, actually, my friend and i decided that what we really needed to do was get all of the really pale people of the world (including ourselves) and get them to lay outside all day. our white skin would reflect tons of sunlight back into space! and what’s a sunburn when you’re saving the world? ^_^
posted by kelly on 9-18-2008 at 5:02 pm
The world doesn’t need “saving”.
posted by Gourry on 9-18-2008 at 6:34 pm
They’ve used white gravel on those flat asphalt roofs for decades. Nothing new here.
posted by PartiallyDeflected on 9-18-2008 at 8:44 pm
Here in the northern reaches, having blacktop roads is good for helping to melt snow & ice in the winter.
posted by Dave on 9-18-2008 at 9:53 pm
Hmm, interesting to consider… My insurance company, thanks to Hurricane Ike, are going to buy me a new roof. I don’t know about white shingles, but maybe a lighter color.
posted by Witty Nickname on 9-18-2008 at 10:39 pm
But isn’t there some rule about white after Labor Day? *rimshot
posted by Johnny Cat on 9-19-2008 at 12:02 am
I happen to work in the construction industry. This is the correct approach to combat the urban heat island effect. The green washed people who preach vegetative roofs are completely off the mark. Highly reflective roofs lower energy consumption (less carbon)and require less maintenance.
posted by Smack on 9-19-2008 at 8:56 am
We’ve been installing white roofs for years. People literally come out of their houses and building laughing, saying, “i had to turn off the air consitioning”. Even the Dept of Energy has a calculator to figure your savings from a white, foam, or cool roof. Go to ornl.gov or http://www.aclimateseal.com
posted by matt on 5-28-2009 at 4:21 pm