Agriculture Secretary Tom Vilsack has urged U.S. builders to prioritize wood in green buildings. He made the recommendation after the U.S. Department of Agriculture’s (USDA) Forest Service concluded in a new report that using wood in building products yields fewer greenhouse gases than using common materials. The report and certain statements made in the wake of its release have not eluded criticism, as evidenced during an interview that Green Building Insider(GBI) conducted earlier this week with the American Institute of Steel Construction’s (AISC) president.
Vilsack said that the report, entitled “Science Supporting the Economic and Environmental Benefits of Using Wood and Wood Products in Green Building Construction,” confirms what many environmental scientists have been saying for years. “Wood should be a major component of American building and energy design. The use of wood provides substantial environmental benefits, incentives for private landowners to maintain forest land, and a critical source of jobs in rural America.”
The report argues that greater use of life-cycle analysis (LCA) in building codes and standards would improve the scientific underpinning of building codes and standards and thereby benefit the environment. “A combination of scientific advancement in the areas of LCA and the development of new technologies for improved and extended wood use are needed to continue the advance of wood as a green construction material. Sustainability of forest products can be verified using any credible third-party rating system, such as Sustainable Forestry Initiative, Forest Stewardship Council, or American Tree Farm System certification.”
“The argument that somehow non-wood construction materials are ultimately better for carbon emissions than wood products is not supported by our research,” said David Cleaves, climate-change advisor for the Forest Service. “Trees removed in an environmentally responsible way allow forests to continue to sequester carbon through new forest growth. Wood products continue to benefit the environment by storing carbon long after the building has been constructed.”
USDA stressed that the use of forest products in the United States currently supports more than one million direct jobs, particularly in rural areas, and contributes more than $100 billion to the country’s gross domestic product.
“In the Rockies alone, we have hundreds of thousands of dead trees killed by bark beetles that could find their way into the building supply chain for all types of buildings,” Forest Service Chief Tom Tidwell said. “Taking a harder look at wood as a green building source could reduce the damages posed by future fires, maintain overall forest health, and provide much-needed jobs in local communities.”
The report suggests several areas where peer-reviewed science can contribute to sustainable green building design and decisions. These recommendations address the following perceived needs for use of wood as a green building material:
- Information on environmental impacts across the life cycle of wood and alternative construction materials needs to be updated and revised.
- Green-building codes and standards should include adequate provisions to recognize the benefit of a life-cycle environmental analysis to guide selection of building materials.
- A lack of educational, technology transfer, and demonstration projects hinder the acceptance of wood as a green building material.
Research recently initiated by the wood-products industry, in partnership with the Forest Service’s Forest Products Laboratory, will enable greater use and valuation of smaller-diameter trees and insect- and disease-killed trees, USDA predicted. “Research on new products and technologies has been initiated, including improved cross-lamination techniques and the increased use of nanotechnology.
“These developments are especially important amid a changing climate because forest managers will need to increasingly thin densely forested areas in the coming years to reduce the impacts from longer and more severe wildfire seasons. Continued research of wood-based products and technologies will contribute to more environmentally responsible building materials and increased energy efficiency.”
The National Association of State Foresters (NASF) applauded the report’s conclusions. “There is a well-established scientific understanding that wood products use less energy and provide greater environmental benefits than alternative building materials. The report’s recommendations calling for the development and use of life-cycle analysis in building codes alongside technology-transfer activities targeted at engineers, architects, and other building professionals will help promote wood as a green building material but are not all that is needed. Sustainable markets provide landowners with more options for addressing regeneration and forest health needs. By embracing the findings of this report and favoring wood, green building markets can significantly advance sustainability goals that extend well beyond the forest.”
Added NASF Executive Director Jay Farrell: “Trees are our greatest renewable resource and economic asset. Both the Forest Service and the green building industry can contribute to the nation’s economic challenges by increasing wood utilization. This can be done in a manner that produces net environmental benefits. If green buildings are the goal, wood is the answer.”
NASF stated that the Forest Service report is consistent with many of the statements found in the organization’s 2008 resolution on green building, which “recognized the value of wood from certified, sustainably managed U.S. forests as a green building material.”
AISC President Responds to Forest Service Report, NASF during
Interview with GBI
During an email interview with GBI, AISC President Roger Ferch weighed in on the issues raised by the Forest Service and NASF. Here is a transcript of the interview:
GBI: What is AISC’s reaction to the Forest Service report and/or the statements that both the Forest Service and NASF made in the wake of the report’s release?
Ferch: We certainly agree with the Forest Service that ‘information on environmental impacts across the life cycle of wood and alternative construction materials needs to be updated and revised’ as well as the call for further development and implementation of life-cycle analysis techniques. Unfortunately, the wood industry is not following this process and is instead making claims that are not supportable, including the fallacy that ‘wood is superior to competing materials.’ To cite just one of many examples, the wood industry claims that wood generates [fewer] quantities of solid waste than structural steel, which is simply untrue. In reality, the waste-generation rate of structural steel is less than 3 percent while the waste-generation rate for wood is greater than 30 percent. Put another way, for every cubic yard of structural steel waste that ends up in a landfill, more than 1,000 cubic yards of wood waste ends up in a landfill.
GBI: Which specific conclusions/recommendations, either made by the Forest Service or NASF, does AISC disagree with the most and why?
Ferch: The recommendation that taxpayer dollars be used to promote wood to the detriment of other important industries employing thousands of American workers is horribly unfair -- particularly when the recommendation is based on incomplete research and biased opinions. It’s unbelievable that the Forest Service couches this as a job-generating activity when it discounts the jobs that will be lost in other construction-industry segments.
Any fair evaluation of the environmental impacts of various building materials requires examining a wide range of factors, including the amount of each type of material required. And it’s important that any analysis goes beyond simply looking at greenhouse-gas emissions while excluding other equally important impacts, such as land and water usage, toxicity, habitat destruction, and eutrophication. To give one example, a typical tree will consume more than 300,000 gallons of water during its life while the production of one ton of structural steel consumes just 60 gallons of water.
Another problem with the Forest Service report is it only cites secondary sources and is not based on primary research. The vast majority of papers cited have been sponsored by the wood industry. While AISC has not reviewed all of these papers, the papers we have reviewed from the wood industry typically ignores resource-consumption issues and does not factor in the release of methane gasses during the end-of-life decomposition of wood products. In fact, it’s not just the growth phase of wood that contributes to its carbon footprint. It’s important to look at the entire life cycle. In the case of wood, a significant portion of the greenhouse-gas impact (measured in equivalent CO2 carbon-dioxide units) is the result of the large amount of waste deposited in landfills, which in turn generates methane (methane is a greenhouse gas with a negative environmental impact 25 times greater than CO2).
In contrast to the wood industry’s hyperbole, a recent Target Zero study, conducted in the United Kingdom by consultants AECOM and Cyril Sweett, looked at three comparative wood and steel structure types and found that in two of the cases the steel-framed structure had a marginally lower carbon impact while in the third the wood structure was slightly better. However, the consultants noted that in all three cases the variation in results was not great enough to definitively make a claim that one material is more carbon-efficient than the other.
GBI: What statistics, if any, can you provide about the amount of steel being used to build buildings each year? How has this figure fluctuated in recent years? Do you have any comparable statistics on steel recycling rates?
Ferch: Approximately 5 million tons of structural steel was used in construction in 2010. While this is down from the peak of 8.5 million tons in 2007, the decline is due solely to the overall shrinking construction market. In fact, steel’s market share has steadily risen in the past five years, in part due to the design community’s recognition of steel as a leading sustainable material.
The average recycled content of domestically produced structural steel over the past 10 years is approximately 93 percent (and more than 90 percent of the structural steel used in the U.S. construction market is domestically produced). During this same time, the recycling/recovery rate for structural steel has been 98 percent. (The recycling rate is a measure of how much steel is recovered rather than entering the waste stream.)
GBI: What will AISC be doing, if anything, to promote to the general public and/or specific groups the merits of steel as an environmentally friendly building material?
Ferch: AISC communicates the sustainable benefits of structural steel to architects, engineers, and building owners through seminars, participation at ‘green’ conferences, and articles and advertisements in a variety of trade magazines. We also invite design/construction professionals and the general public to participate at SteelDay activities throughout the U.S., where the sustainable characteristics of structural steel are discussed.
GBI: What proposals, legislative or otherwise, is AISC tracking that involve both steel construction (in the building sector) and environmental issues?
Ferch: AISC has participated in the development of ASHRAE [American Society of Heating, Refrigerating and Air-Conditioning Engineers Standard] 189.1 and submitted comments on both the International Green Construction Code and the various versions of LEED [Leadership in Energy and Environmental Design].
We have also cooperated with other building-material organizations (ready mix, cement, aggregate, cold-formed steel) in opposing ‘Wood First’ legislative efforts in the Pacific Northwest, where the wood industry attempted to mandate the use of wood in all publicly funded structures.
GBI: Other comments?
Ferch: Structural steel has long been considered the premier green construction material, and the structural steel industry is continuing to improve its leading environmentally friendly position by further reducing greenhouse-gas emissions. While numerous legislative and regulatory efforts in recent years have targeted emissions, energy efficiency, and related environmental concerns, the structural steel industry has been proactive in pursuing measures of its own that typically exceed regulatory requirements.
The results of structural steel industry efforts are evident in recent [U.S.] Environmental Protection Agency findings on greenhouse gasses, which show that the iron and steel industry reduced carbon emissions by 47 percent between 1990 and 2005 and achieved the highest overall emissions reduction of any major industry: 67 percent. By comparison, initiatives such as the Kyoto Protocol would have required U.S. industries to reduce emissions by 5.2 percent by 2012. In addition, the majority of the structural steelmaking process’ carbon footprint is attributed to electrical use. As the electrical grid becomes more renewable, steel’s environmental impact will decrease -- a unique opportunity for the steel industry.
At the same time, the industry remains the world leader in the use of recycled material and end-of-life recycling, with the recycled content of the structural steel beams and columns produced at U.S. mills averaging 93 percent and a recycling rate of 98 percent. The steel industry has also: continually pursued methods for reducing energy consumption; reduced energy intensity per ton of steel by 29 percent since 1990; [and] committed itself to the Climate Vision program to reduce energy usage by an additional 10 percent by 2012.