By Loretta Hall
At least three different types of evaluation and certification programs are being used to ensure that engineered wood products can legitimately be called green building materials. The programs address environmental issues related to the production, utilization, and life cycle performance of structural wood products.
Although they focus on different aspects of wood construction, the programs do interface. Green buildings must not only be built of materials that are environmentally sound, but they also must perform in environmentally responsible ways throughout their lifetimes.
Certifying Wood Sources
Both the U.S. Green Building Council and the National Association of Home Builders recognize the importance of verifying that wood used in construction has been produced using sustainable forestry practices. For example, the USGBC's Leadership in Energy & Environmental Design program allows green building certification points for using wood certified by the Forest Stewardship Council.
According to APA–The Engineered Wood Association, the FSC represents 110 million acres of forests in 73 countries, including 23 million acres in the United States and 10 million acres in Canada. However, two other well-established sustainable forestry certification programs—the Sustainable Forestry Initiative and the Canadian Standards Association—represent a total of 62 million acres in the United States and 154 million acres in Canada.
"This is one of our greatest arguments against LEED," says Marilyn LeMoine, APA's market communications director. "With only 23 million acres in the U.S. and 10 million acres in Canada, it simply makes it too difficult for builders to source product that's FSC-certified. There's no reason to make certified wood so hard to get." She notes that the NAHB Model Green Building Guidelines accept certification by FSC, SFI or CSA and give them equal rating in the credit system.
Certifying Design and Construction
"If you're using engineered wood products already, you can almost automatically start adding up green building credits," says Tom Williamson, vice president for quality assurance and technical services for APA. "And if you're not, it's a quick way to get there."
Williamson asserts that using a variety of engineered wood products when building a home can produce as many as 85 points under the Model Green Home Building Guidelines — nearly one-third of the 261 points needed for Bronze certification. For example, he says, using structural insulated panels generates 12 energy efficiency points, plus 4 more if they are used on rooms with cathedral ceilings. Using glulam, SIPs and pre-cut joist systems produces 19 points for reducing quantity and waste. Using I-joists is worth 16 points for resource efficiency because the engineered wood product uses 36–46 percent less wood fiber than full-dimension lumber, depending on the joist spacing.
Certifying Long-Term Results
The Consortium for Research on Renewable Industrial Materials, a non-profit corporation formed in 1997 by 15 research institutions, conducts life-cycle inventory and assessment studies of wood in construction.
In 2004, CORRIM undertook two case studies to compare wood with concrete and steel for residential construction. Using computer modeling, the researchers evaluated the total energy used to manufacture and transport building materials, build each house, maintain it for a 75-year life cycle, and then demolish or dispose of it. However, the analysis did not include the energy use or emissions associated with operation of the house. The researchers found that compared with a wood-framed house, a steel-framed house contained 17 percent more embodied energy, and produced 14 percent more air pollutants and 312 percent more water pollutants.
Similarly, a theoretical comparison of concrete-block and wood-framed houses found that the concrete version contained 16 percent more embodied energy and produced 23 percent more air pollutants and 51 percent more solid waste. (For more information on the case studies, see www.corrim.org/reports/2005/final_report/index.htm.
The computer analyses were done with the Environmental Impact Estimator software developed by the Athena Institute. Based on building design and construction materials, the software helps designers optimize operating and embodied energy effects over a building's complete life cycle. Results are stated for a range of indicators. "It's like looking at a food label," says Wayne Trusty, president of the Athena Institute.
Doing a life-cycle assessment helps designers optimize selected environmental impacts of their projects. It can also earn them points. Williamson says performing a life cycle analysis can be worth 8 points toward Model Green Home Building certification as an innovative option for resource efficiency.
Freelance writer Loretta Hall can be contacted through her Web site, SubsurfaceBuildings.com.
| 
