Up on the Roof

February Article:
Roofs are perhaps one of the most important components of an energy-efficient building. Unfortunately, compared to items like doors, windows, and lighting, roofs are generally much less durable and much less energy efficient.
Over the lifetime of a building, a roof needs to be replaced an average of four times. More than 75 percent of the roofing work in the United States involves reroofing, and roofing materials are the second-largest contributor to solid waste in the United States.
Energy-efficient roof technologies are fairly straightforward. Manufacturers have developed lighter-colored shingles and tiles, usually containing a coating of titanium dioxide, since they absorb less heat than a typical asphalt shingle and can last twice as long. Since lighter surfaces are easily discolored by fungus, a fungicide coating normally gets added. Many of the new roof coatings are even self-cleaning to retain reflectivity properties and reduce air conditioning requirements.
Lighter-colored roofs are slightly more expensive. However, the small cost difference–$25 for a 1,000-square-foot roof–will easily pay for itself in one summer.
Roof overhangs are another way to trim summer cooling bills. For many homes and businesses in warmer climates, overhangs reduce solar heat gain and interior temperatures. They can also be designed to let direct sunlight into a living space during winter, but keep things shaded in summer.
Source: U.S. Department of Energy, Energy Efficiency and Renewable Energy www.eere.energy.gov