Greener Roofing Options

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Studies conducted by the Florida Solar Energy Center compared the performance of roofing materials. Asphalt shingles had a solar reflectance ranging from 3 percent (onyx black shingles) to 31 percent (“white” shingles). Brown wood shingles were found to have a solar reflectance of about 22 percent, and a brownish-orange terra-cotta cement tile had about a 24-percent solar reflectance. In contrast, white and light-colored metal roofing had reflectances ranging from 50 percent to 66 percent.

Improving the albedo of your roofing surface can cut cooling costs by up to 50 percent, depending on how much insulation is in your ceiling or roof. And, while you save on cooling costs, you’ll also prolong the life of your shingles. According to www.energystar.gov, roofs with high solar reflectivity maintain a more even core temperature, which protects against the shingles’ deterioration.

“Cooling-load avoidance can be important in some situations,” Wilson says. “But if a house is properly insulated to at least R-24 [the higher the R-value, the lower the heat flow] in the ceiling or roof, the heat gain or heat loss through solar energy absorption on the roof surface is really pretty minor. With the insulation levels recommended in a green home, albedo is not a significant consideration.”

Asphalt Options

According to the Asphalt Roofing Manufacturers Association, more than 12.5 billion square feet of asphalt shingle products are made each year — enough to cover more than 5 million homes annually.

The attraction to asphalt shingles is they are affordable and lightweight — no additional engineering is needed to put them on your rooftop. Of all the roofing products available, they usually are the least expensive upfront, but proportionately less durable over time.

“It’s a hard sell to push homeowners to longer-lasting alternatives because those alternatives are usually a lot more expensive, and the homeowner probably doesn’t expect to stay in a house for more than 20 years,” Wilson says.

“Asphalt is a bad roofing option from an environmental standpoint,” Wilson adds. “In addition to all the resources going into making such a short-lived product, there is a tremendous amount of solid waste generated from the removal of old shingles.”

Every year about 11 million tons of asphalt shingles are shucked into landfills, according to www.shinglerecycling.org. In fact, old asphalt shingles constitute about 3 percent of all municipal solid waste. Asphalt shingles can be recycled, but so far the technology to do so is in its infancy, and widespread asphalt shingle recycling is not available.

Asphalt shingles come in two different kinds: organic-based or fiberglass-based. The organic kind are made from materials such as recycled waste paper, wood fibers and felt, then saturated with a specially formulated asphalt coating and surfaced with weather-resistant mineral granules. Organic-based asphalt shingles contain about 40 percent more asphalt per square (100 square feet) than fiberglass, which gives them more weight, durability and blow-off resistance. Fiberglass shingles start with a glass-fiber reinforcing mat that is coated with asphalt and mineral fillers for adhesion, then embedded with ceramic granules. Asphalt shingles come in many different shapes, sizes, thicknesses and grades. If you do choose to use asphalt, make sure to pick the most durable shingle that suits your structure’s needs, usually an organic variety.

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