The current energy crunch has made conservation measures within commercial and institutional buildings more important than ever. Cool roofing is gaining popularity with building owners due to its ability to reduce cooling and heating energy usage. Utility companies are also interested in cool roofing because it can help reduce peak demand during summer afternoons, preventing power disruptions. And, from an environmental point of view, cool roofing can also help mitigate a phenomenon known as "the heat island effect." When looking at cool-roof options, don't forget metal - its cool-roofing characteristics might surprise you.
The Washington, D.C.-based U.S. EPA estimates that an ENERGY STAR®-labeled roof can lower roof temperature by as much as 100 degrees F. To date, more than 60 percent of the products listed on the ENERGY STAR-labeled directory are metal roofing products or coatings used specifically in the metal roofing industry.
The Oakland, CA-based Cool Roof Rating Council (CRRC) is now recognized as the sole entity responsible for listing roofing products that are candidates for the California Energy Code, Title 24. The 2005 version of Title 24 contains language specific to cool-roofing requirements for low-slope applications. Roof-system compliance with Title 24 is based on meeting prescriptive requirements of 0.70 total solar reflectance (TSR), 0.75 thermal emittance (TE), and being a CRRC-listed product. Compliance can also be achieved using a method of building component or whole-building trade-off calculations. Some pre-painted metal roofing can meet the prescriptive requirements. However, unpainted metal roofing, such as Galvalume® sheet, cannot comply with the prescriptive criteria. For this type of metal roofing product, the trade-off calculations can be used to bring the building's energy budget into compliance.
To offset the expense, take advantage of the tax incentives for commercial construction offered in the Energy Policy Act of 2005. An eligible commercial building owner can receive a tax deduction equivalent to $1.80 for every square foot of the building - if the building is designed to conserve energy. The use of energy-efficient building envelope components is required, and a cool metal roof can be used to lower the cooling energy used in the building.
Use of metal roofing can also result in points toward certification in the U.S. Green Building Council's LEED for New Construction (LEED-NC) rating system. One point is awarded for metal roofing in the Heat Island Roof section (where cool roofing criteria are defined). Additionally, metal's high recycled content can be used to raise the building's weighted average recycled content in order to receive up to 2 points. The fact that metal is 100-percent recyclable helps with the Waste Management section of LEED. Cool metal roofing can even be part of the energy-simulation calculations in the Energy and Atmosphere section, where up to 10 points are available through energy-optimization evaluations.
As the cool-roof movement continues to grow in the wake of rising oil, gas, and electricity costs, metal roofing is poised to deliver a cool solution.
Scott Kriner is a technical consultant to Glenview, IL-based The Metal Initiative, an industry-wide program designed to educate building owners, architects, and contractors about the use and selection of metal roofs and walls in commercial, industrial, and institutional buildings. For more information, visit (www.themetalinitiative.com).
