Whitewashing roofs is gaining in popularity across the nation as a simple way to increase energy efficiency.
Energy Secretary Steven Chu has said that painting roofs white is a quick and low-cost way to fight global warming.
Last May, New York’s Mayor Bloomberg began a six-month trial period of whitewashing NYC roofs to slash energy use. More than 1,500 volunteers and seventeen companies worked together on the CoolRoofs project to paint the roofs of 105 buildings. The goal of painting 1 million square foot of roof space was reached earlier this week.
The Mayor’s Office says that a coat of reflective white paint can reduce air conditioning costs in single-story buildings by up to 50%, 25% in two-storey buildings and up to 10% in five-storey buildings. The paint can also extend the life of a roof by reducing the wear and tear associated with intense heat (New York and many other cities experienced record breaking heat this summer).
Herb Van Gent of the Wayne, New Jersey’s GAF Materials supplied much of the reflective paint used in New York’s trial period. His infrared (heat sensing) gun measured 143 degrees on a square of black top roof and only 98 degrees on an area with a single-coat of reflective white paint. His science agrees with the Mayor’s correlation between cooler buildings, energy savings, and sustainability.
In Philadelphia, a city sponsored Coolest Block Contest awarded a block of row houses with whitewashed roofs. Residents like Terry Jack noticed an immediate difference: “I noticed the difference the very next morning after they painted the roof. It was a good 15 degrees cooler inside; it was much more livable.” The city hopes such initiatives—along with their Greenworks plan—will lead to less energy consumption and lower utility bills.
In Arizona, cool (white) roofs are mandatory on all state and state funded buildings.
Arthur Rosenfeld, former energy commissioner of California, believes the trend will continue and says that on average, a 1,000-square foot roof that is painted reflective white can save 10 tons of carbon dioxide which is the equivalent to the emissions of a car for about 2.5 years. Nationally, cool roofs could save an estimated 2 billion tons of carbon dioxide which is like taking 20 million cars off the road for 20 years.
While the trend of whitewashing roofs does lead to significant energy savings, the most efficient roofs are those built with energy efficiency in mind. (The Energy Department offers a tax credit for cool roof materials used during roof replacement.)
With information from The Wall Street Journal’s Sean O’Driscoll
