| 6 Tips for Specing and Installing an Energy-Saving Cool Roof | |
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Few home builders or homeowners opt for energy-efficient cool roofs, says California building science consultant Steve Easley, because that typically means the roof has to be white. But that's changing.
Now manufacturers-with the help of research conducted by the military-have devised a formula for treating shingle-topping granules so darker colors-as deep as forest green, brown, and even "cool" black-also reflect enough heat to make a difference in how hot the home's attic gets and how high the owner's cooling bill soars.
Combine the new technology with California's Title 24 stipulations that require pros to increase the roof's efficiency, and cool roofs appear to be gaining acceptance, especially among green builders. Add to that the attention of contractors and consumers looking to earn points toward green certification, or who just want to reduce a home's overall energy costs, and reflective or cool roofing materials-available in asphalt, metal, and composite-could slowly move into the mainstream.
If you or your customers are considering a cool roof, which in some cases carries a higher price tag than traditional asphalt shingles or metal, here are seven facts to consider:
1. Heating bills. A reflective roof can help keep a house cooler when the hot sun beats on it, but it will not lower a home's heating bill, and may even slightly raise it. It makes sense to install a cool roof, which reflects heat but does not absorb it, only where the summers are extremely hot or humid. Most residential cool roofs are in southern and southwestern states, although homes where the summer air is especially humid-in cities like New York, Washington, or Indianapolis, for instance-also are candidates. Still, the Cool Roof Rating Council says cool roof owners may pay slightly more to heat their homes, although the summer savings outpace the increased heating bill.
2. Performance ratings. The Cool Roof Rating Council uses two measures to rate the performance of cool roofs. The first, solar reflectance, refers to how much of the sun's energy is reflected by the roof. The other, thermal emittance, measures how well the product releases any heat that it does absorb. Both use a scale from 0 to 1, with those measuring closer to 1 performing best.
3. Energy Star savings. The council estimates that a cool roof can save a homeowner 7% to 15% in cooling costs. Energy Star recognizes cool roof products that reduce peak cooling demand by 10% to 15%. To obtain the Energy Star label, steep-slope products must have an initial solar reflectance of at least 0.25. Three years after installation, the roofing product must achieve a solar reflectance of 0.15 under normal conditions. Energy Star does not require third-party certification of performance. The council, which measures performance but does not impose minimum levels, verifies that the products perform at the levels stated by the manufacturer.
4. Long-lasting results. Some studies claim that cool roofs last longer than traditional products because they do not absorb heat. Tucson roofer Daniel Roberts says that's true. "Darker shingles naturally will cook at a hotter temperature and tend not to hold up as well as the lighter color," says the founder and owner of Castle Roofing. "A good rule of thumb in Arizona: The lighter the shingle the better, not just for reflection and energy savings, but for the shingle's life itself."
In fact, notes Roberts, he was installing light-colored shingles on Tucson rooftops long before "cool roofing" became an energy-efficiency buzzword. "It's nothing new."
5. Insulation issues. Thick insulation and radiant barriers can cancel out the need for a cool roof. Roberts notes that placing a cool roof over an attic with 10 or 12 inches of insulation will result in only "negligible" additional energy savings. Easley agrees: "Even if you reflect 90% of the heat, that doesn't mean you'll reduce your energy bills by that much," he says, "because the codes already require that you have insulation in the attic." For homes with air conditioning ducts in the attic, though, cool roofing makes sense, he notes, especially if the ducts leak.
6. Higher prices. Some pros find cool roofing products garner more interest than sales because of their higher price tag. In the Northeast, for example, Tamko's Lamarite slate composite cool roof shingles cost $80 more per 100 square feet installed than the non-reflective Lamarite products, estimates Tim Lutrell, a Tamko vice president.
"A lot of folks ask about this stuff, but as you go to higher prices, some folks get scared off," agrees Scott Heitmeier, business manager of steep-slope roofing for ABC Supply. "That's something that has to be dealt with if these products are truly going to gain their share in the market."
On a final note, while there are a variety of methods to increase a roof's efficiency-by upgrading insulation, for example-cool roofs make sense for many regions. Most of Los Gatos Roofing's customers opt to install cool roofs for the extra protection against the heat, notes co-owner Randy Brown.
Sharon O'Malley is contributing editor to Building Products magazine and ebuild.com.
Custom-Bilt Metals. Titan Cool Roof is a two-coat system with a minimum solar reflectance of 25%--and up to 70% on lighter colors, the maker claims. When applied and cured on properly prepared substrates, the material demonstrates color stability, chalk resistance, durability, abrasion resistance, chemical resistance and flexibility, the manufacturer says. 800.826.7813. www.custombiltmetals.com.
MonierLifetile. The concrete roof tiles in the manufacturer's Hartford Slate collection exceed LEED requirements for reflectivity and emissivity. The color-through tiles resist surface damage and degradation, the company says. The series comes in a variety of light and dark colors, including charcoal brown blend (pictured), and is available in northern and southern California and the Pacific Northwest. 800.669.8453. www.monierlifetile.com.
CertainTeed. Landmark Solaris shingles, which comply with Energy Star guidelines, are available in deep hues, including heather blend, resawn shake, burnt Sienna, and weathered wood. The product can reduce the roof's surface temperature by 20% during warm months, the maker says, and is designed to resist winds up to 130 mph. The shingles are rated by the Cool Roof Rating Council and meet California's Title 24 requirements. 800.233.8990. www.certainteed.com.
Eagle Roofing. Approved by Energy Star and rated by the Cool Roof Rating Council, concrete Cool Roof Tiles can save 10% to 30% on air conditioning bills, the firm states. The tiles come in multiple profiles and colors. 909.822.6000. www.eagleroofing.com.
DaVinci. EcoBlend roofing tiles, which offer the look of slate, reduce solar heat gain to save homeowners 7 percent to 15 percent on cooling costs, the firm states. The product is rated by the Cool Roof Rating Council and by Energy Star. It is 100 percent recyclable, does not release or discharge toxins, and has an anticipated life span of 50-plus years, the maker says. 800-328-4624. www.davinciroofscapes.com.
Tamko Building Products. Lamarite slate composite shingles now come in five energy-saving cool colors that reflect the sun's heat instead of transferring it to the attic. The product, which is rated by the Cool Roof Rating Council, comes in widths of 5, 7, and 12 inches, and in five colors: terra-cotta, pale olive, cool grey, natural sand, and almond shell. 800-641-4691. www.tamko.com.
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