Sustainable Design

Life Cycle Assessment

In the past, the green building movement has taken a prescriptive approach to choosing building materials.

This approach assumes that certain prescribed practices—such as using local materials or specifying products with recycled content—are better for the environment regardless of the product’s manufacturing process or disposal. Today, it is being replaced by the scientific evaluation of actual impacts through life cycle assessment (LCA).

LCA is an internationally recognized method for measuring the environmental impacts of materials, assemblies or whole buildings over their entire lives—from extraction or harvest of raw materials through manufacturing, transportation, installation, use, maintenance and disposal or recycling. It allows design professionals to compare different building designs based on their environmental impacts and make informed choices about the materials they use.

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LCA studies consistently show that wood outperforms fossil fuel-intensive materials such as steel and concrete in terms of embodied energy, air and water pollution, and carbon footprint.

One study conducted by the Consortium for Research on Renewable Industrial Materials (CORRIM) compared the environmental impacts of wood-frame and steel-frame homes in Minneapolis, and wood-frame and concrete-frame homes in Atlanta (the framing types most common in each city). In both cases, LCA showed that the wood-frame homes performed substantially better than their non-wood counterparts. According to the report, the homes framed in steel and concrete had 17 and 16 percent more embodied energy, respectively, than the wood-frame homes. Likewise, the carbon footprint was 26 percent higher for the steel-frame home and 31 percent higher for the concrete-frame home than the homes framed in wood.

In the past, LCA has been perceived as too complex and time consuming for regular use. However, with tools such as the ATHENA EcoCalculator for Assemblies, which is free and includes ready-to-use LCA data for hundreds of common building assemblies, the use of LCA is now much easier. As LCA is written into a greater number of green building codes, standards and rating systems, tools like the EcoCalculator that make LCA more accessible to mainstream building designers can be expected to increase.

  • The Athena InstituteLCA research, information and tools, including North America’s only LCA tools for whole buildings—including the free ATHENA® EcoCalculator for Assemblies and its parent tool, the ATHENA® Impact Estimator for Buildings
  • Consortium for Research on Renewable Industrial Materials (CORRIM) – Research and information materials focused on the environmental impacts of wood and other bio-based materials
  • Dovetail Partners Inc. – Authoritative information about the impacts and trade-offs of environmental decisions, including consumption choices, land use and policy alternatives
  • National Institute for Standards and Technology – BEES® (Building for Environmental and Economic Sustainability) software for product-focused LCA