White roofs for a green planet

Written By Hank Green - Sep 15, 2008

"Why did we decide that having roofs be black was a good idea? I know tar is black, and that's what most roofs are sealed with ... but I really can't imagine a much dumber choice.

Sure, black is great in the winter, when the roof becomes a giant solar heat collector. But there's no way to turn that giant solar heat collector off when the summer rolls around. Simply painting roofs white in warm climates decreases air conditioning bills for those buildings by 20 percent. That's one reason why California has required all new buildings to have white roofs for the past few years.

Now there's even more reason to spend the extra dough. If all the roofs in the world were white, enough sunlight would reflect back into the atmosphere to significantly reduce the effects of global warming. Such a simple change, such a massive effect!

This new study says that if the 100 biggest cities painted all their roofs white, and switched their road materials to lighter colours (concrete instead of asphalt) it would reflect enough light and heat back into space to entirely offset the warming of the last few decades.

It's not a true fix for the problem, obviously....."