The green building trend in building design and construction promotes energy efficient, environmentally responsible and sustainable building practices. Green building designers and contractors select appropriate sites, specify sustainable products and materials, incorporate natural lighting and install energy efficient mechanical equipment to minimize the structures’ environmental impact. Using wood products in green building construction is one of the best ways to achieve sustainable construction since wood is the world’s most renewable resource.
Structural Glued Laminated Timber
As the premier engineered wood product, glued laminated timber (glulam) is one of the greenest structural building products. Adding to the benefits of wood in general, glulam further optimizes the wood resource by utilizing higher strength lumber only in the areas where stresses are highest and lower grades of lumber in other laminations. Glulam has been manufactured in the U.S. since the late 1930’s and is therefore, one of the oldest engineered wood products. The manufacturers of glulam have continually improved their manufacturing processes to produce a consistently reliable, high performance wood product.
Since 1952, the American Institute of Timber Construction has been the recognized leader in the development of standards for the manufacture and use of glulam. It’s member companies are committed to providing the very best, high performance sustainable product.
Tools have been developed to assist designers in the decision making process due to the complexity of assessing the environmental performance of buildings. Multiple green building rating systems, including Green Globes and LEED (Leadership in Energy and Environmental Design) were developed to simplify the process. For wood products, forest certification programs have been developed to ensure that our forests are harvested in a sustainable manner. A powerful analysis tool called Life Cycle Assessment (LCA) provides a “cradle to grave” approach to compare the environmental impact of construction materials.
Life Cycle Assessment
LCA is a performance-based approach used to assess environmental impact. LCA quantifies the overall effects of a product, process, or activity on the environment over its lifetime. This includes material extraction, manufacturing, transportation, installation, use, maintenance, and disposal or re-use.
The tools used to evaluate LCA are continuously improving to allow users to make informed choices based on current data concerning commercial processes and environmental impacts. LCA has shown that wood products offer clear environmental advantages over other materials.
According to a recent report by the Consortium for Research on Renewable Industrial Materials (CORRIM), when using LCA to assess the full ecological impact of a building material, wood is far more environmentally beneficial than steel or concrete, as it:
- Requires less energy to produce
- Sequesters greenhouse gases
- Removes pollutants from the air rather than emitting them
- Produces less waste in the manufacturing process
Where LCA tools are used to assess environmental impact, they provide a science-based approach to measuring environmental effects. Although the science isn’t perfect, it is far superior to the subjective approach used by some green building rating systems, where points are assigned based upon non-scientific criteria.
Sustainable Forest Management Practices
There are three national sustainable forestry management (SFM) certification programs in use in the United States: The Sustainable Forestry Initiative® Program (SFI), the American Tree Farm System (ATF) and the Forest Stewardship Council (FSC). While these standards have their differences, they all provide assurance that certified wood has been harvested using sustainable forest management.
The SFI program is based on the premise that responsible environmental behavior and sound business decisions can co-exist. SFI, Inc. is a fully independent, registered non-profit, with a governance structure with equal representation across three chambers: social, economic and environmental. There are over 150 million acres third party certified to the SFI Standard in the US and Canada. In addition, the SFI Chain of Custody program includes over 750 sites in North America.
The ATF system is the oldest voluntary, third-party certification program in the world. It was formed in 1941 by landowners. Its mission is primarily to educate and support small non-industrial forest landowners. There are over 91,000 individual certified Tree Farms in the United States, encompassing over 23 million acres.
FSC is an independent, international not-for-profit and non-government organization based in Bonn, Germany. The many regional FSC forest management standards, while based on FSC’s 10 principles and criteria of responsible forest management, vary as to their specific requirements. Currently there are approximately 26 million acres of FSC-certified land in the United States.
Green Building Rating Systems
Two rating systems are available to designers and builders to improve the environmental performance of commercial buildings. These two systems are LEED and the Green Building Rating System® developed by the U.S. Green Building Council (USGBC) and Green GlobesTM, a web-based tool developed by the Green Building Initiative.
Both systems include rated design elements that contribute to the environmental performance of buildings. However, point allocations in the two systems vary in their emphases. Green Globes places stronger emphasis on energy use, while LEED allocates more points to material selection. The main point of green building is to promote energy conservation to reduce the impact of construction on the environment. Green Globes better achieves the goal of higher energy savings.
A major aspect of material usage where the two programs diverge relates to wood certified to sustainability standards. LEED excludes the Sustainable Forestry Initiative® program and the American Tree Farm System, where Green Globes specifically includes them. A report by Tim Smith et al (2006) at the University of Minnesota shows that the FSC certification is among the most costly of all LEED credits to achieve. This is due to the fact that only 10% of the forests in the U.S. are certified by FSC, and that credit is only given if the wood is harvested within 500 miles of the point of manufacture. Again, Green Globes better achieves the goal of providing economical construction and higher energy conservation.
A major concern about LEED is that it is not developed by a consensus process which gives all affected parties an opportunity to be heard. Although the USGBC has been accredited by the American National Standards Institute (ANSI) as a green building Standards Development Organization, none of their LEED products have been developed using ANSI approved procedures, nor has USGBC committed to use those ANSI-accredited procedures for any of its LEED rating products.
Green Globes was developed and is maintained through a transparent and open process approved by ANSI (ANSI/GBI 01-2010). Furthermore, Green Globes has used LCA to evaluate competing products since its inception. The openness of the process and the scientifically based criteria make Green Globes a superior green building rating system to LEED.