Guide to Cool Roofs - Energy

1 Guide to Cool Roofs Cool Roofs can save Energy as well as beautify your home. The immediate and long-term benefits of Roofs that stay cool in the sun have made cool roofing the fastest growing sector of the building industry. Studies exploring the Energy efficiency, cost-effectiveness, and sustainability of cool Roofs show that in warm or hot climates, substituting a cool roof for a conventional roof can: Reduce the annual air-conditioning Energy use of a single-story build- ing by up to 15%. Cool Roofs help lower indoor air temperatures by reflecting sunlight and decreasing heat absorption. Cool interior spaces in buildings that do not have air condition- The coolness of a roof is determined by two properties and their combined ing, making occupants more effects on surface temperature: comfortable.

2 Solar reflectance the fraction of sunlight that is reflected. Reduce carbon emissions by Thermal emittance the efficiency with which a surface cools itself by lowering the need for fossil fuel- generated electricity to run air emitting thermal radiation. conditioners. Potentially slow climate change by Both properties are measured on a scale of 0 to 1 the higher the values, the cooling the atmosphere. cooler the roof . If you are installing a new roof or The Emergence of Cool Roofs remodeling an existing building, there Cool roofing is not a new concept. In the mid-1980s, researchers at DOE nation- are a range of cool roof options to fit al laboratories in Tennessee and California were measuring the Energy -saving your needs and save money.

3 Benefits of solar radiation control coatings on test Roofs . Although Energy savings were confirmed in these early studies, they were not yet sufficient to How Cool Roofs Work lead roofing designers and installers to switch from traditional dark-colored Traditional dark-colored roofing ma- roofing systems. terials absorb sunlight, making them warm in the sun and increasing the Did you know? need for air conditioning. White or Solar reflective Roofs , solar reflective pavements, and vegetation could lower urban air special cool color Roofs absorb less temperatures, saving additional Energy and improving air quality. sunlight, stay cooler in the sun and transmit less heat into the building.

4 Cool roofing also reduces peak demand for electricity, helping to lower costs and This reduces the need for air condi- avoid power outages. tioning by lowering interior building Cool roof products dominate the commercial roofing marketplace in warm and hot temperatures. climates. continued >. Cool Roofs Today Save Cool asphalt shingles currently sell The incremental cost of keeping Energy and Money for up to $ per square foot more a cool roof clean and reflective (if than conventional asphalt shingles. any). Today both white and cool color Cool versions of some other roofing products are available for low-slope materials may require a reflective Further Resources and steep-slope Roofs .

5 Cool choices surface coating that adds about $1 per Cool roof Rating Council Products now exist for most traditional roofing square foot to the installed cost. Directory materials. Cool roofing should be considered whenever construction, an Installing a white roof on a com- Energy retrofit, or a roof replacement mercial building yields annual DOE Building Energy Software Tools is being planned. It is rarely economi- Energy savings worth up to $ Directory cal to replace a mechanically sound per square foot and installing a roof just to increase its solar reflec- cool color roof on a home yields tools_directory tance. Check to see if a annual Energy savings worth up to $ per square foot.

6 Savings Energy 101: Cool Roofs cool roof would be cost-effective for vary, and are greatest in hot and you. warm climates. Use the calculator Cool products are generally eco- at to estimate your Energy STAR Cool Roofing nomical on low-slope Roofs for savings. Materials commercial or industrial buildings. A cool roof may increase the Cool options are available for most need for heating Energy in winter traditional roofing materials. by reflecting sunlight that would White Roofs are coolest, but cool otherwise warm the building. Even Cool Roofs Calculator colors are a popular alternative for in mixed climates, however, winter Roofs that can be seen by neighbors.

7 Penalties can be smaller than sum- Energy STAR lists about 3,000 mer savings. compliant cool-roofing materials. Federal tax credits are available How to Select and Buy Cool for some cool materials, including Roofing Materials asphalt shingles and metal products. The Energy and cost savings that can Many state agencies and utility pro- be achieved by using cool roofing grams offer incentives for installing technologies depend on many fac- cool Roofs . tors, such as climate and building Cool roof credits are offered in characteristics. sustainable building programs such as the Green Building Three aspects of cool roofing Council's Leadership in Energy and technologies also affect their Environmental Design (LEED).

8 Cost-effectiveness: For low-slope Roofs (pitch 2:12), The aged solar reflectance and cool thermoplastic membranes, thermal emittance of the roof (since elastomeric coatings, and metal products are available. many Roofs become less reflective Financial Incentives over time, Energy savings should be Tax credits, incentives, and rebates may be For steep Roofs , cool asphalt based on long-term values of solar available in your area. Please visit shingle, clay tile, concrete tile, and reflectance and thermal emittance). for more metal products are available. The incremental initial cost of the information. cool roof (if any). EERE Information Center 1-877-EERE-INFO (1-877-337-3463).

9 DOE/EE-0384 February 2011. Printed with a renewable-source ink on paper containing at least 50% wastepaper, including 10% post consumer waste.