Roofs are perhaps the important component 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
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.