Science fiction often imagines futuristic dwellings of plastic and steel, but many of today’s advanced, environmentally friendly homes are being built with something more familiar: wood.
The idea of wood as a renewable resource is not new to many in the wood-products and construction industries, but wood products businesses are trying to raise its public profile.
“We’ve always considered wood to be a green product, simply because it’s renewable,” said Boise’s Chuck Miller, a National Association of Home Builders Certified Green Professional.
The University of Idaho recently changed the name of its Forest Products program to Renewable Materials to reflect the growing interest in green construction and to promote wood to green builders.
“Over the years we’ve see the rise in interest and activity in green building, where wood plays a major role,” said Tom Gorman, a professor of renewable materials.
“Steel and concrete are mined and extracted,” Gorman said. Most plastics are synthetic materials made from petrochemicals. Trees, on the other hand, can be replanted.
He listed several environmental advantages of wood: it’s recyclable, it requires a low amount of energy in manufacturing, and trees store carbon, so some carbon remains sequestered when wood is used for building.
Gorman said that when graded by a life cycle assessment – a way of measuring the environmental impact of a material or process – wood has “clear advantages” in reducing greenhouse gas emissions.
For example, a study by the Consortium for Research on Renewable Industrial Materials published in the June 2004 Forest Products Journal (Vol. 54, No. 6) used a life cycle assessment to evaluate the differences between wood and steel construction in a cold climate and wood and concrete construction in a warm climate. The study found that over the lifetime of a residential building, both steel and concrete would be more harmful to the environment overall than wood.
Miller said wood also is more cost-effective for homebuyers and builders than products such as steel framing or insulated concrete forms.
He said most people focus less on the interior structure of a house and more on the finished product. His customers prefer hardwood floors and wood cabinetry, though they’re seeking more variety in material and design.
Product engineering advances are giving builders and customers more – and greener – options for using wood.
For example, Miller has used engineered wood beams that don’t require solid lumber, but are manufactured from smaller, faster-growing trees. He said new forms of laminated-wood flooring are not only more stable and longer-lasting than traditional hardwood floors, but also are less expensive and use less lumber. The flooring can be finished in the factory, keeping the volatile organic compounds found in wood-finishing products out of homes.
Students at the University of Idaho have developed prototypes of new wood-based green building materials, Gorman said. These “emerging technologies” include a process for hardening low-quality pine to make it stable, fireproof and suitable as a substitute for oak flooring. Another product in the works mixes sawdust and recycled milk jugs to make composite lumber.
“In general, engineered wood … is a more efficient use of wood and relies less on large-diameter, old-growth deciduous trees,” according to a February 2008 article in Building Design & Construction magazine by Barbara Horwitz-Bennett and C.C. Sullivan titled “Using Wood for Sustainable Design & Construction.”
Gorman said he started seeing a move toward building low-energy homes in the mid-1980s, and that included efforts to be efficient in the use of wood. One area of progress has been durability. Because wood is biodegradable, it has to be protected.
“Some engineered wood products outperform wood in terms of resistance to cracking, shrinkage, and warping, as well as offering a high degree of strength,” Horwitz-Bennett and Sullivan wrote.
Wood is abundant in Idaho, which has about 17.6 million acres of timberland, according to the Idaho Forest Products Commission. Timberland is forested land that is not reserved in a national forest or other area that would restrict harvest.
Gorman said green-building practices favor locally grown wood, because using local materials reduces the amount of fossil fuels needed for transport.
“We’re using a sustainable material that’s locally grown,” Gorman said. “We’re fortunate that we have a good wood basket, a sustainably managed forest within the state of Idaho.”
“The use of imported wood and rare hardwoods, despite their attractiveness and elegance, is often criticized for originating from non-certified, poorly managed forests, primarily in less well-developed tropical countries,” Horwitz-Bennett and Sullivan wrote. Their article states that although certification programs have started to include more imported and rare woods, tropical forests are still depleting rapidly.
Gorman said Idaho’s sustainable forest management is key, and third parties can verify such management. For example, the Forest Stewardship Council certifies several Idaho wood-product companies, including Boise Cascade and Idaho Forest Group.
Recycling old wood products in new construction is another growing trend, Gorman said.
Moscow’s Wasankari Construction gathers wood from homes it tears down and reuses it in new construction. Co-owner Melanie Wasankari said older timbers aren’t used for framing homes, but can be used as ceiling beams, molding, flooring, mantels, built-ins and more.
She said customers like using recycled wood materials because it allows them to create a home that is eco-friendly and has character.
“You can’t do that with new stuff,” she said. “You’re coming out there and reusing things that you can’t find anywhere else.”
Wasankari said the hard part of reusing wood is making sure it’s extracted in a cost-efficient manner. Wood can’t simply be torn out and reused; it has to be in good structural shape. For example, she said, flooring may not be reusable, but the wood underneath could be worth reclaiming.
Gorman said wood that isn’t suitable for as a solid wood product for construction can still be used in green homes as energy. Wood can be ground into fuel to heat the house, or into mulch for landscaping.
Miller said his company uses cellulose insulation that is a wood-fiber product made from old newsprint.
“We just keep on using (wood) right down to its final use, when it’s composted or burned,” Gorman said.
Gorman said he sees a bright future for wood products in green construction.
“More and more, the value of wood as a sustainable, renewable construction material will become more and more apparent,” he said.
Miller said a wood-framed home, if properly built to prevent moisture buildup, will last well into the future. He noted the houses people ordered from the Sears catalog in the early 1900s that are still found around the country today.
“Wood homes can last hundreds of years,” he said.