Green building programs have been developed over the past 10 to 15 years with the objective of shifting the built environment toward more sustainability. As the influence of these programs grows, it is critical that their guidelines and requirements be rational, realistic, comprehensive, and science-based to ensure they actually achieve positive outcomes. As they currently stand, building with wood is being unfairly penalized.
The leading green building program in North America, which is known as LEED (it stands for Leadership in Energy and Environmental Design), has significant flaws. There have been some recently proposed changes to LEED, which, if approved, are a step in the right direction. However, more fundamental changes are needed in the process used to identify green building materials.
LEED’s Green Building Rating System is a program of the U.S.-based Green Building Council (USGBC). The LEED program was initiated in 1998 as a voluntary, consensus-based national standard for developing high performance, sustainable buildings. It uses a point system in rating buildings, with points awarded in a number of environmentally related categories. The number of points earned is used to determine attainment of certification levels.
In the building materials section, points are heavily concentrated in three areas: low-emissions products, products with recycled content, and, for wood products only, Forest Stewardship Council (FSC) certification.
Although these three areas have some merit, there are several environmental impacts and attributes of materials that are not included. There is no mention of these important factors: embodied energy in products or product assemblies; emissions linked to production and use of construction materials; and consideration of life cycle inventory data.
In May 2005, LEED commissioned an examination of wood-related credits under its building materials rating system. This has resulted in a recent proposal that suggests the award of a credit to all wood building materials verified to be of legal origin and certified under any of the mainstream North American certification programs: Sustainable Forestry Initiative (SFI), Canadian Standards Association (CSA), or FSC. The net effect is to recognize responsibly sourced wood as a preferable construction material. FSC-certified wood would still receive an additional credit under this system.
Significantly, however, there is no discussion in the draft document about certification of any material other than wood.
Let’s consider this singular focus on wood. FSC certification requires attention be paid to land tenure issues, observance of indigenous people’s and workers’ rights, and community relations, in addition to a wide range of environmental impacts linked to raw materials extraction and processing. This level of assessment is certainly an enlightened approach to materials selection. But if these factors constitute essential elements in selection of an environmentally preferable building material, why does LEED not require any material other than wood to comply with such standards?
For instance, growing and harvesting of many agricultural products such as bamboo are known to have all of the problems often attributed to wood and also often bear the additional environmental burdens associated with monoculture plantations and intensive agricultural practices. Why is bamboo accepted without question and even singled out by LEED as an “environmentally preferable” material, both currently and in the recent proposal for change?
Bamboo is at least renewable. What about the non-renewable resources? It is well known that materials such as steel, aluminum, and concrete are associated with very high environmental costs, even when they contain recycled content. However, in ignoring measures such as embodied energy and total emissions linked to producing these materials – the kinds of information provided by a life cycle inventory – LEED currently treats steel that contains recycled content as an environmentally equivalent material to FSC-certified wood. This is an absurd situation. Why doesn’t LEED consider life cycle inventory data as one part of its materials rating system?
There is no justification for singling out one – and possibly the most environmentally friendly – construction material (wood) for a host of special requirements.
It is time to require rigor in the assessment and designation of environmentally preferable building products. Specifically, LEED needs to scrap its prescriptive system of materials assessment using single attributes and replace it with a scientifically based system. In addition, if certification programs are to be required as part of materials assessment, then action should be taken to ensure that the same questions are asked of, and the same requirements imposed on, manufacturers and suppliers of the full array of building materials.
Today LEED is in the forefront of green building programs in the United States in terms of both participation and influence. But to actually create meaningful change in the behavior of those in the construction industry, it must be willing to make significant changes to itself and its systems.