reflectance and thermal emittance, with both values being as close to 1 as possible, or an SRI value that is as high as possible. Reaping The Benefits Of Cool Roofs Cool roofs are one of the easiest ways to increase the sustainability of your build-ing while improving the bottom line, and eco-conscious and business savvy building owners across the country are taking note. Cool roofs are basically roofing products that minimize the heat transfer to the build-ing below, while quickly shedding any heat that has penetrated the surface. These characteristics can be achieved through either light colored surfaces or the integration of pigments in the material for-mula with high spectral reflectance. These pigments reflect in the near infra-red spectrum, as opposed to the visible spectrum, allowing color products to retain reflective properties. Studies have shown that on particularly hot days, lighter surfaces stay up to 70 degrees Fahrenheit cooler than dark sur-faces. This can have a significant effect on the amount of cooling energy your building uses, as well as the lifespan of cooling equipment and the roof itself. Because cool roofs reflect more heat than traditional roofs, they help keep the building below cooler. By keeping the building cooler, cool roofs decrease the need for air conditioning. Keeping your roof at a constant tempera-ture will also help extend the life of the roof itself, and some studies have even shown that the insulation below your roof is more effective if it is kept at a lower temperature. Altogether, cool roofs can help you save up to 40 percent in cooling energy over traditional dark roofs and can equate to sig-nificant savings in roof maintenance. Cool roofs not only make financial sense for building owners, but can also improve the sustainability of your facility. The decrease in cooling energy that you benefit from indirectly helps combat global warming by decreasing the need for more fossil fuel. By decreasing your roof’s temperature, you are also helping reduce the ambient air temperature around your building, combat-ing heat-related and smog-related illnesses such as asthma and heat stroke, as well as a phenomenon in cities called the urban heat island effect. The urban heat island effect is the increased temperature of urban centers over surrounding areas due to the concen-tration of non-reflective surfaces. Lowering the urban heat island effect can help lower cooling energy loads across the city. Choosing A Cool Roof Now that you understand the energy perfor-mance properties and benefits of cool roofs, how do you go about choosing a cool roof that is right for your building? The steps outlined below can help you get the most out of your cool roof. 1. Check for requirements and rebates Codes are catching on to the benefits of cool roofs, and your local or state energy or building codes may require cool roofs for new construction or even replacement roofing projects. Voluntary green building programs such as the U.S. Green Building Council’s (USGBC) Leadership in Energy and Environmental Design (LEED) program offers a credit for cool roofs. Codes and green building programs usu-ally specify a minimum solar reflectance, thermal emittance and/or SRI value. Additionally, always check to see if your local utility offers a rebate for cool roofs. 2. Find a cool roof that meets your requirements The most reliable source for solar reflec-tance and thermal emittance values are third-party product rating programs, like the Cool Roof Rating Council’s (CRRC) Product Rating program. The U.S. Environmental Protection Agency’s (EPA) ENERGY STAR program is another resource for identifying cool roof products. The CRRC rates the energy performance properties of roofing products through their Accredited Independent Testing Laboratories (AITL). The CRRC rates both the initial and aged — over three years — solar reflectance and thermal emittance values in order to get a comprehensive view of how a roofing prod-uct will perform over its entire lifetime. The CRRC does not set minimum stan-dards for what deems a “cool” roof; this is left to the code bodies and voluntary programs. The CRRC does maintain a free online list of rated products and their radiative properties. Third-party rating programs are crucial because they offer standardized, consistent test methods and credible ratings. 3. Select the roof that is right for your building You may want to consider what makes sense for your roof’s slope, budget, climate and energy savings goals. The U.S. Department of Energy (DOE) has developed two cool roof calculators where you can enter specific information about your building and location to deter-mine the potential energy savings of install-ing a cool roof. The calculators can be used to help you compute a simple payback analysis unique to your project parameters. If sustainability is a concern, you may also want to consider the environmental impacts of roofing materials. These include the recycled content, tox-icity, greenhouse gas emissions linked to shipment and weight and wastes associ-ated with raw material extraction and appli-cation methods. Work with a contractor to determine what will work best for your building. With these steps in mind, you are on your way to choosing a cool roof that meets your budget, environmental factors and aesthetic requirements. Make the sustainable switch and have the coolest building on the block. CM Jessica Clark, Leadership in Energy and Environmental Design Accredited Professional (LEED AP), is the marketing liaison for the Cool Roof Rating Council (CRRC). She organizes edu-cational outreach for the program including pre-sentations, writing and speaking engagements, as well as marketing material. The Cool Roof Rating Council is a non-profit organization that main-tains a credible, third-party rating program for measuring and labeling the radiative properties of roofing products. The Council publishes these rat-ings via its online directory as a public service for use by building owners, architects, code officials and other interested parties. For more information, please visit www.coolroofs.org or call us toll free at (866) 465-2523. www.cmmonline.com 39
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