Green Building and Wood Products
Wood and Carbon
Although LCA recognizes products associated with low CO2 emissions, long-term carbon storage is not one of the metrics measured. Wood performs well on both counts—but its benefits are most evident when the forest/wood cycle is viewed as a whole.
In the process of photosynthesis, trees absorb carbon dioxide from the atmosphere, release the oxygen and incorporate the carbon into their trunks, branches, leaves and root systems. Trees that decompose and die in the forest release this carbon back into the atmosphere slowly, and it is released more quickly in forests that succumb to insects, disease or wildfire. However, if the trees are harvested and manufactured into lumber and other forest products, these products continue to store carbon while the forest regenerates and once again begins absorbing CO2. In the case of buildings, this carbon is stored for the lifetime of the structure—or longer, since wood also lends itself to adaptation, salvage and re-use. Wood can also be used as a low-carbon substitute for fossil energy.
Photo by Robert Creamer Photography
LEED Platinum
James and Anne Robinson Nature Center – Columbia, Maryland
Architect: GWWO, Inc./Architects
WoodWorks Institutional Wood Design Award, 2014
The second aspect to wood's relatively light carbon footprint is that it grows naturally and requires comparatively little additional energy to manufacture into products. This gives wood an environmental advantage over construction materials such as steel, cement and glass, the production of which requires temperatures of up to 3,500° F and large quantities of energy, resulting in substantial greenhouse gas emissions.7
Photo by Richard Lubrant
Carbon Benefits
Crescent Terminus – Atlanta, Georgia
Architect: Lord Aeck Sargent
According to the Wood Carbon Calculator for Buildings (www.woodworks.org), Crescent Terminus has a carbon benefit equivalent to 2,583 cars off the road for a year or the energy to operate a home for 1,149 years.
Taking advantage of wood's carbon and other environmental benefits in building construction comes with a bonus—namely that, in many cases, wood construction is less expensive than other building solutions. For example, one high school in Arkansas documented in a case study saved $2.7 million by changing the design of its new school from steel and masonry to wood—while achieving a carbon benefit of 11,440 metric tons of CO2.8
New Materials Create New Possibilities
The emergence of mass timber products such as cross laminated timber (CLT) is allowing designers to create a broader range of lower-impact structures. Internationally, for example, CLT's relatively light carbon footprint is helping to drive a trend toward taller buildings, such as the eight-story Bridport House in the United Kingdom and the 10-story Forté in Australia.
Estimated by the Wood Carbon Calculator for Buildings, based on research by Sarthe, R. and J. O'Connor, 2010, A Synthesis of Research on Wood Products and Greenhouse Gas Impacts, FPInnovations. Note CO2 on this chart refers to CO2 equivalent.
Although relatively new in North America, CLT has been used in a variety of building designs, from the LEED Gold-certified Earth Sciences Building at the University of British Columbia to the new Fort McMurray Airport, where designers have taken a “first principles” approach to sustainability, blending best practice with the monitoring approaches of various green building rating systems. In the U.S., examples include the The Crossroads, a 52,000-square-foot staff and visitor facility at the LEED Gold-certified Promega Feynman Center in Wisconsin, and a two-story school in West Virginia.
What the Future Holds
With growing concerns over climate change and the environmental impact of buildings, it stands to reason that green building concepts will be increasingly incorporated into structures of all kinds. What began as an interest in reducing energy consumption to save money in the 1970s has led to today's net zero energy objectives, and net zero carbon is another frontier. With attention turning away from the prescriptive approach to sustainable design and toward LCA-based tools that identify the lowest impact alternatives, more designers will become familiar with the environmental advantages of wood, and wood products will be a building material of choice for a growing range of applications.
For more information on the themes described in this article, download the Green Building with Wood Toolkit at rethinkwood.com.
Endnotes
1. Werner, F. and Richter, K. 2007, Wooden building products in comparative LCA: A literature review; A Synthesis of Research on Wood Products & Greenhouse Gas Impacts, FPInnovations, 2010
2. Wood and Human Health, FPInnovations, 2012; Wood as a Restorative Material in Healthcare Environments, FPInnovations, 2015; Appearance Wood Products and Psychological Wellbeing, Society of Wood Science and Technology, Rice J., Kozak Robert A., Meitner Michael J., and Cohen David H., 2006
3. Wood and Human Health, FPInnovations; 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
4. Wood and Environmental Product Declarations, GreenSource CEU, July 2013, http://continuingeducation.construction.com/article.php?L=312&C=1116&P=1
5. Building Materials in the Context of Residential Construction – Phase I, 2005; Life Cycle Environmental Performance of Renewable Building Materials in the Context of Residential Construction – Phase II, 2010, Consortium for Research on Renewable Industrial Materials
6. A Synthesis of Research on Wood Products & Greenhouse Gas Impacts, FPInnovations, 2010
7. Ibid
8. WoodWorks case study: El Dorado High School, 2012, http://www.woodworks.org/wp-content/uploads/CS-El-Dorado.pdf.
 |
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 products and the forests they come 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 |
Notice
