A Natural Choice
LEED®. The Leadership in Energy and Environmental Design system was developed by the U.S. Green Building Council and provides third-party verification that a building or community was designed and built using strategies that improve performance in the following areas: Energy Savings, Water Efficiency, CO2 Emissions Reduction, Stewardship of Resources and Sensitivity to their Impacts, and Indoor Environmental Quality. LEED rating systems are tailored to various market segments. LEED version 4 was approved in 2013. LEED is also used in countries such as Canada, China, India, Mexico, etc.27
Living Building Challenge (LBC). This program of the Cascadia Green Building Council is mainly active in the U.S. and Canada and is meant to be the next step after LEED Platinum and a step before regenerative buildings. It is intended "to define the highest measure of sustainability attainable in the built environment based on the best current thinking—recognizing that 'true sustainability' is not yet possible." As of August 2013, six building projects have achieved LBC certification.28
NAHB Model Green Home Building Guidelines. These guidelines, now part of NAHB's National Green Building Program, were published in 2005. They are the basis for the Green Scoring Tool, and can also function as the foundation for local organizations' green building programs.29
Sustainable Forest Management— |
Wood products that come from sustainably managed forests are a good choice for sustainable building. Responsible forest management in North America has resulted in more than 50 consecutive years of net forest growth that exceeds the amount of timber harvested. Canada and the United States regulate harvest levels with an upper limit to maintain forest resources. In Canada, where 93 percent of the forest land is publicly owned, government authorities set prescriptive harvesting levels following a detailed analysis of timber supply. In the U.S., which has a large number of smaller-scale private land owners, harvest levels are based on maturity criteria at the forest stand level. North America has more certified forests than any other part of the world and all major forest certification programs in North America are recognized globally. Forests offer many different values, which responsible forest practices seek to maintain and protect, including wildlife habitat, biodiversity, recreation and products that range from lumber and paper, to medical supplies, fuel and clothing. |
The SB Tool. This software implementation of the Green Building Challenge assessment method has been under development since 1996. Initially launched by Natural Resources Canada, the process is now the responsibility of the International Initiative for a Sustainable Built Environment.30
A 2010 study by Light House Sustainable Building Centre found that, while the intensity of wood used in a project did not have a large impact on the number of total potential credits, it was clear that certain rating systems are more "wood-friendly" than others.31 Rating systems for single-family homes, such as BuiltGreen, were most predisposed towards wood, while commercial building systems such as LEED (U.S. and Canada) made it slightly easier to score points by not using wood. "Rating systems have become the definition of energy-efficient and environmentally responsible building, but that represents a limited view," says Helen Goodland, previously with Light House and now a principal with Brantwood Consulting, a green building technical advisory firm. "Wood can help designers create greener buildings, yet we found that wood's most significant ecological benefits—that it is the only carbon-neutral construction material and that it can significantly reduce a building's life cycle impacts—are largely unrecognized by the most commonly used rating systems." Goodland notes that most rating systems have gaps in areas where wood may play a positive role, including acoustical performance, life cycle assessment and material efficiency.
An alternative approach is Passive House, which focuses solely on reducing energy consumption, without other requirements. Aiming to cut heating energy consumption of buildings by 90 percent, Passive House emphasizes superinsulation and air-tight construction primarily heated by passive solar gain and by internal gains from people, electrical equipment, etc. without applying expensive active technologies like photovoltaics or solar thermal hot water systems. Over the last 10 years more than 15,000 buildings in Europe—including homes as well as schools, factories and office buildings—have met the Passive House standard.
Green Hammer Design & Build in Portland, Oregon, was among the first to design a U.S. office space to Passive House standards. The 2,600-square-foot wood frame structure with a truss roof system is an office for Oregon's Farmworker Union. "We used wood because of its relatively low carbon footprint, its low embodied energy, our ability to source reclaimed wood, and wood's cost effectiveness," says Stephen Aiguier, Green Hammer's Founder and President. "Because it is a smaller building, wood was far more economical than masonry construction."
As demand for sustainable building continues to increase, the design community will need to understand what is meant by true sustainability. Current practices and materials may need to be reconsidered in light of that definition. Still, there are a range of options for sustainable design, and innovative architects are finding improved environmental performance via many avenues. One way is certainly by using wood. A carbon-neutral, energy-efficient material that can achieve the three goals of true sustainability—environmental, social and economic—wood is also a truly renewable building material in the architect's toolbox.
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Details of Oregon's Farmworker Union building, designed by using Passive House standards. Image courtesy of Green Hammer Design & Build |
| ENDNOTES |
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1. http://www.epa.gov/sustainability/basicinfo.htm#sustainability 2. http://info.aia.org/toolkit2030/advocacy/aia.html 3. Werner, F. and Richter, K. 2007. Wooden building products in comparative LCA: A literature review. International Journal of Life Cycle Assessment, 4. Gustavsson and Sathre 2006; Gustavsson et al. 2006 5. Nebel, Perez, Buchanan, 2009 6. http://www.corrim.org/pubs/articles/2004/FPJ_Sept2004.pdf 8. http://www.whitehouse.gov/administration/eop/ceq/sustainability 9. Carbon Management, June 2011, Vol. 2, No. 3, pages 303-333, Life Cycle Impacts of Forest Management and Wood Utilization on Carbon Mitigation: Knowns and Unknowns, Bruce Lippke, Elaine O'neil, Rob Harrison, Kenneth Skog, Leif Gustavsson, Roger Sathre 10. http://woodworks.org/files/PDF/publications/Carbon-Footprint.pdf 11. Estimating 2003 Building-Related Construction and Demolition Materials Amounts, U.S. Environmental Protection Agency, 12. Sector Analysis: Generation and Recovery of Solid Wood Waste in the U.S., Biocycle, August 2012, USDA Forest Products Laboratory, 13. Wood in the Human Environment : Restorative Properties of Wood in the Built Indoor Environment http://hdl.handle.net/2429/28644 14. The Human Response to Wood, http://continuingeducation.construction.com/article.php?L=312&C=1104 15. Approaching the Design and Planning for School Capital Program with Wood, Mikio Moronuki, Research Centre for Educational Facilities, Tomoe Corporation; Building Schools with a Wooden Design, Ben Nakmura, Institute of Technologies 16. C. Kelz1,2, Grote V.1,2, Moser M.1,2, Interior wood use in classrooms reduces pupils’ stress levels, 1Institute of Physiology, Medical University of Graz, Austria; 2HUMAN RESEARCH, Institute for Health, Technology and Prevention Research, Weiz, Austria 17. World Bank Forests & Forestry, http://web.worldbank.org/WBSITE/EXTERNAL/TOPICS/EXTARD/EXTFORESTS/ 18. State of the World's Forest Report 2009, United Nations Food and Agriculture Organization, http://www.fao.org/docrep/011/i0350e/i0350e00.htm 19. http://www.peri.umass.edu/236/hash/efc9f7456a/publication/333/ 20. http://www.bsc.ca.gov/home/calgreen.aspx 21. Estimated using the WoodWorks Carbon Calculator, www.woodworks.org 23. http://www.builtgreen.net/ 24. http://www.ibec.or.jp/CASBEE/english/overviewE.htm 26. http://www.gbca.org.au/green-star/green-star-overview/ 27. http://www.usgbc.org/DisplayPage.aspx?CategoryID=19 28. http://living-future.org/lbc 30. http://www.iisbe.org/taxonomy/term/105 31. http://www.naturallywood.com/sites/default/files/Green-Rating-System.PDF |
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The reThink Wood initiative is a coalition of interests representing North America's wood products industry and related stakeholders. The coalition shares a passion for wood and the forests it comes from. Innovative new technologies and building systems have enabled longer wood spans, taller walls, and higher buildings, and continue to expand the possibilities for wood use in construction. www.rethinkwood.com |
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