Cool Roofs: An Easy Upgrade

By Cathy Zoi via the Energy Blog on Energy.gov

December 14, 2010

Check out Google Earth – the ‘view from above’ of your favorite American city. And look at the roofs of the office buildings, warehouses, shopping centers, and even the homes. Most of them are probably pretty dark in color – and this means they heat up a lot when the weather is warm – up to 50 degrees hotter than light roofs. All of those dark roofs mean that as a nation we’re using a lot more air conditioning than we need to. At least a billion dollars a year in extra power bills, in fact. And when you combine hot roofs with dark roads and parking lots, we get the ‘urban heat island’ effect: cities tend to be 2-5 degrees hotter than less urban areas just because of all the dark surfaces.

But there’s something we can do about it: changing to a ‘cool roof.’ The Department of Energy just did this in our Washington, DC headquarters. It was time to replace our roof anyway, so for no extra cost we went to a ‘cool’ white material. And we’re hoping others follow this lead.

Here's a video of Secretary Chu giving his thoughts on our new cool roof:



A cooler roof means lower energy bills –up to 10-15% lower – when it’s warm out because your air conditioner doesn’t have to work as hard. Saving energy means lower greenhouse gas emissions because we don’t need to burn as much fossil fuel. And less heat absorbed by building rooftops means cooler communities in the summer.