If you've ever lived in a city, near a city, or been on the roof of a city building in the summer, you know the urban jungle gets hot as hell. Growing up on Long Island, it wasn't uncommon for my nearest metropolis, New York City, to be close to 10 degrees hotter than my home town.
There are lots of reasons why this is the case in cities around the world, at least some if it can be attributed to all those black, tar-paper roofs soaking up rays all day long. If we were to paint urban rooftops white, a new report suggests, the Big Apple's fever would go down by as much as 2 degrees Fahrenheit on a warm summer day.
The new modeling study, due to appear in Geophysical Research Letters, puts the first hard numbers behind Energy Secretary Stephen Chu's suggestion earlier this year to paint roofs white as a way of saving energy and fighting global warming.
Given that cities around the world vary a whole lot in their climate and construction, the benefits of painting roofs white to ward off the Sun's heat is going to have an array of effects. For example, if you live in Reykjavik, Iceland you might want to keep your black roof because you're way more concerned with keeping your place warm than cool. Santorini, Greece is so hot that they went white a long time ago (pictured above). The amount of insulation in your building matters a whole lot, too.
But overall, researchers conclude that white roofs could cut the so-called urban heat island affect by as much as 33 percent globally, or an average of 0.7 degrees Fahrenheit.
For temperate places like New York, you've got to balance the amount of energy saved on less air-conditioning in the summer with the increase in heating in the winter. So maybe what we really need are roofs that can change colors depending on the energy needs of the building.
For more on making rooftops green, see Discovery News' 10 Ideas for An Environmentally Friendly Roof
Image: Roger Pielke Sr.'s climate blog
Tags: Climate Change, Global Warming, Green Science, Physics
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