How Green Is Your Building’s Wood?
The environmental attributes of wood for construction of homes has been measured and found to be superior to alternatives such as steel and concrete. The United States Green Building Council’s Leadership in Energy and Environmental Design (LEED) program recognizes wood for green building, especially if it is grown within a few hundred miles of where it is grown. As an extra measure of assurance, some architects, developers and builders specify that wood products are certified by an independent third party as coming from sustainable forests. Among some 40 different certification programs worldwide, The American Tree Farm System, Sustainable Forestry Initiative and the Forest Stewardship Council are examples of organizations which offer certification verified by third-party auditors to ensure that sustainable forestry practices are followed.
How can architects, developers and builders know for sure that lumber for building their projects comes from sustainably managed forests? Sustainability is defined internationally as: meeting the needs of the present generation without compromising that ability for future generations.
Translated to forestry, sustainability strives to balance the interdependent and sometimes competing interests of the environmental, economic and social benefits that forests provide. That means harvest sites must be replanted, and that other assets of the forest— soil and water quality, fish and wildlife habitat, and recreation opportunity, among them—must be protected.Small and large landowners alike manage some forests for specific purposes. Thinning Douglas-fir and trimming lower branches allows specialty stands to grow more quickly and produce clear wood with few knots producing wood highly desired for windows and decorative construction.
An ideal way to ensure that wood is harvested in an environmentally and socially responsible manner is to choose wood from a state with strong forest practice laws. Tough standards and regulatory oversight offer assurance that comprehensive rules are followed and enforced. While other states may follow best management practices, their guidelines are not codified into law. And wood from international sources may have even far less environmental protection.
On working forestlands, good forest practices require that some trees and snags be left behind during harvest for wildlife habitat purposes. Along with buffer zones along forest streams, road-building activities must be approved under law and water runoff after harvest from the state’s plentiful rainfall is closely monitored to safeguard future forest resources. Key regulated practices and a host of other laws govern road construction, bridges, culvert placement, public safety, stream enhancement and wildlife protection, and include:
•Landowners must replant the forest within two years after harvest.
•Within six years, the harvest site must regenerate into a healthy trees.
•Live trees, snags and fallen logs must be left after harvest to provide wildlife habitat.
•A buffer of trees left alongside fish-bearing and drinking water streams,to ensure cool, clean water.
•Timber harvesting, road building and using herbicides are restricted close to streams
•Except when approved under special conditions, a clearing cannot exceed 120 acres.
Working forests are lands managed primarily for wood production. and which ensure that trees are replanted after harvest and that buffer zones protect forest streams. Once trees are harvested, how green is the next stage? Timber manufacturing sector made early investments in technology for making raw logs into finished lumber. Timber is processed in high-tech, low-waste mills where lasers scan logs in three dimensions, computers decide the maximum number of boards, and every inch of log, down to the chips and sawdust, is put to use. Mills in the United States and Canada, often generate their own electrical energy from these wood by-products. How far must the wood be shipped to reach your project? The United States imports some one-third of its wood supply, mainly from Canada. It takes large amounts of fossil fuels to transport wood, and thus local sourcing is another factor of sustainability. Wood harvested within a 500-mile radius is the standard for defining "local."
How green is your building's wood? Green comes in many shades. But architects, developers and builders can feel assured of sustainability using wood products that are locally grown and manufactured, and that are grown in places with stringent and comprehensive laws that govern the practice of forestry.