Earth day, April 22, comes on a Sunday this year, making a weekend
paint project a perfect way to celebrate. Just painting the surface of a
black roof white can lower its temperature on a hot afternoon by as
much as 50 to 65 degrees.
And cooling down the house is good for the wallet and the environment.
Research published in Environmental Research Letters online finds
that if all of the world’s urban areas were outfitted with white roofs
and light-colored pavement, it would cool the planet by as much as 0.13
degrees Fahrenheit, saving up to 150 billion tons of carbon dioxide
emissions–equal to 50 years’ worth of emissions from all the world’s
cars.
The new work, by Hashem Akbari and colleagues of Concordia University
in Montreal, used estimates for the amount of urban roof and pavement
surfaces globally combined with climate models to determine the effect
on global temperatures of changing the reflectivity of a surface, known
as its albedo.
