How your roof is heating up the city

Did you know that your roof might be the reason it's so darned hot in New York City in August? Well, maybe not your roof (especially if you don't live in NYC), but, according to the U.S. Environmental Protection Agency, roofs in general play a big role in something called the urban heat island effect. The urban heat island effect is a phenomenon in which cities are warmed 2 to 10 degrees more than surrounding areas ... and, as nice as that may sound in New York in January, it's not a good thing.

You see, 90 percent of roofs in the U.S. are made out of a dark-colored material. Because dark colors absorb rather than reflect heat, the buildings covered by those roofs become warmer. Then the people who are in those buildings crank up the AC as high as it will go. All those air conditioning units running at full steam means increased energy use, while the higher temperatures mean increased air pollution.

A good, cool roof reflects most solar energy and then emits, rather than absorbs, the leftovers that it hasn't reflected. This keeps buildings and homes cooler and energy usage down.

So where does that leave you? What can you do to help minimize the urban heat island effect in your city (or just lower your energy consumption in the summer, if you don't live in the city)? Simple: Tell your contractor, or the company putting the new roof on your house that you want a white roof with "high solar reflectance and thermal emittance." And then check with your state's energy department or your local power company, because a few have been known to give rebates for cool roofs. California did and it looks like PG&E might kick a few dollars back your way ... and Southern California Edison ...

Image www.sxc.hu