Why White Roofs Will Slow Global Warming
Obama's Nobel prize-winning green guru and US Secretary of Energy Dr. Steven Chu claims that painting your roof white can help reduce global warming significantly.
Speaking yesterday from London prior to a conference on climate change, Dr. Chu said that making the planet's roofs and pavement a lighter color could result in the environmental equivalent of taking the world's cars off the road for 11 years.
Sensible folks in hot climates like Greece caught on to the "cool roof" idea hundreds of years ago, opting to paint their homes white to reflect sunlight away from their dwellings in order to stay cool.
The concept is ridiculously simple: as sunlight beams into the Earth's atmosphere, about half the sun's energy shines as visible light, which then hits the rooftops of houses. If a roof is white, the sunlight will reflect back into atmosphere instead of heating the roof and in turn heating the house and the earth. In the case of a typical dark-colored roof, the sunlight converts directly to heat rather than bouncing off as light. It's the same reason black cars get steamy before white cars and why asphalt roads heat up faster than lighter concrete sidewalks.
Not only do white roofs keep things cooler naturally, they save on air conditioning costs and cut carbon emissions drastically. In fact, painting a 1,000 square foot rooftop white could save 10 tons of CO2 emissions and about 20 percent of your air conditioning costs – that's a savings of $1 billion per year in the US alone, considering that 90 percent of US roofs are black. The cool roof movement has already started in the US with Georgia and Florida offering incentives to home owners who install white or light-colored roofs. Come July, California law will require residential sloping roofs to be light-colored cool roofs.
While it's no cure-all for global warming, the cool roof concept is catching on. As the dog days of summer approach and your cooling costs increase, will you consider changing your home's black asphalt roof to a "cool roof"?
Check your local bylaws and building suppliers for cool roof green rebates and tax breaks! For more info and the skinny on incentives, check out the EPA's articles on cool roofs.