Wood Rates: How Wood Products Stack Up in Green Building Systems
How Wood is Currently Rated
The Light House Sustainable Building Centre study commissioned by Forestry Innovation Investment examined the ways in which the world’s major green building rating systems incorporate wood, pinpointing where the ecological value of wood products was most recognized. Systems surveyed include: BREEAM, Built Green™, CASBEE®, Green Globes™, Green Star, LEED®, the Living Building Challenge, NAHB Model Green Home Guidelines, and the SB Tool. As several systems such as LEED and Built Green offer a range of applications for specific building types, a total of 18 applications were assessed. All systems are voluntary and unregulated.
| Systems Studied | |
BREEAM. The UK-based Building Research Establishment's (BRE) Environmental Assessment Method for offices, multi-family residential and ecoHomes offers credits in ten categories according to performance which are then added together to produce a single overall score on a scale of Pass, Good, Very Good, Excellent and Outstanding. Established in 1990, BREEAM is the basis for most other rating systems and with more than 100,000 certified buildings, it is the world's most widely used green building rating system. Built Green™ A voluntary program for residential construction, Built Green was started in the U.S. by home builders. In Canada, owned and managed by the Built Green Society of Canada, this system is open to members of participating Home Builders' Associations and offers certification for new single-family homes and row homes, and a pilot in multi-story residential. CASBEE® (The Comprehensive Assessment System for Building). Japan's green standard uses building environmental efficiency (BEE) as a basis for assessment by dividing the building environmental quality and performance by the building environmental loads. Developed by a committee under the initiative of the Ministry of Land, Infrastructure and Transport in 2001, the system has sequentially developed various categories including new construction, existing buildings and renovations. Green Globes™. In the U.S., Green Globes is owned and operated by the Green Building Initiative which, in 2005, became the first green building organization accredited as a standards developer by the American National Standards Institute (ANSI), and began the process of establishing Green Globes as an official ANSI standard. In Canada, the federal government uses the Green Globes suite of tools and it has been the basis for the Building Owners and Manufacturer's Association of Canada's (BOMA) "BESt" program. Green Globes is a web-based tool that provides feedback on how to reduce operating costs and environmental impacts of commercial projects based on input from the design team. Third-party certification of the site results in a higher rating. |
Green Star. Australia's green standard launched by the Green Building Council of Australia in 2003. Since then, a variety of Green Star rating tools have been developed from multi-unit residential to retail, office, and office interiors. There are currently similar programs in New Zealand and South Africa. LEED® (Leadership in Energy & Environmental Design). The U.S. green building certification program 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 3 was launched in 2009. LEED is increasingly in use in other countries such as Canada, China, India and Mexico. Living Building Challenge. This program of the Cascadia Green Building Council is mainly active in the US and Canada and is meant to be the next step after LEED Platinum and a step before regenerative buildings. 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." No project has yet to incorporate all facets of the program. NAHB (National Association of Home Builders) Model Green Home Guidelines. Published in 2005, these guidelines, now part of NAHB's National Green Building Program, include the ANSI approved ICC-700-2008 National Green Building Standard. They are the basis for the Green Scoring Tool, and can also function as the foundation for local organizations' green building programs.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. |
Generally, every rating system offered a certain percentage of credits that could be achieved with the use of wood. In most cases, wood is recognized by rating systems in the following areas:
Certified wood. Most rating systems give credits for wood that has been certified by a respected third party verifier as coming from a sustainably managed forest. Different rating systems allow for different certification schemes, with some more inclusive than others. While rating systems reward projects that use certified wood, they do not hold competitive materials such as concrete or steel to the same level of accountability, nor penalize them for failing to achieve a similar standard.
Recycled / reused / salvaged materials. Many rating systems give credits for recycled content, though only some allow salvaged wood to count towards this credit.
Local sourcing of materials. Most rating systems credit use of local materials, though the intent differs and ranges from supporting the local economy to reducing the environmental impacts from transportation. "This makes sense on an intuitive level since less energy will be required to transport the materials," writes Wayne Trusty, President of the Athena Institute, a non-profit organization that seeks to improve the sustainability of the built environment through better information and tools. "But there are a tremendous number of factors that influence whether or not a material produced locally is better for the environment, including the sources of its components, type of manufacturing process and mode of transportation. So, in fact, using locally-produced materials could either add to or detract from a building's sustainability."
Some rating systems use local content credits with the intent of rewarding lower embodied energy and/or life cycle emissions, when in fact a life cycle analysis approach may be more appropriate. Rather than placing a travel distance limit for sourcing the material a more rigorous approach would be to have separate credits for local resources and embodied energy, as is done in Japan's CASBEE.
Building techniques and skills. Rating systems that focus on low-rise residential homes tend to be less performance-based and more prescriptive standards than those for commercial buildings, and frequently prescribe specific building techniques, such as advanced framing that reference wood.
Waste minimization. Many systems credit diversion of a certain amount of construction waste, or for minimizing wasted woodcuts. Architects may want to confer with builders on how to earn points by implementing certain job site protocols in order to leverage their use of wood in green building credits.
Indoor air quality. Most rating systems demand that all wood adhesives, resins, engineered and composite products contain no added urea formaldehyde and have strict limits on VOC (Volatile Organic Compound) content. While many products (such as carpets), have created clear guidance to specifiers about their toxicity, information about wood products (particularly panel products such as plywood and MDF) can be less straightforward, compounded by challenging tracking and quality control systems.
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