Environmental Footprint
The chart below illustrates how each of the designs performed against five key indicators of environmental impact. With two exceptions, the wood-framed homes performed substantially better than their non-wood counterparts. The steel design produced slightly less solid waste and there was no significant difference in emissions to water in Atlanta.
MINNEAPOLIS DESIGN | Wood | Steel | Difference | (% Change) |
Embodied Energy (GJ) | 651 | 764 | 113 | 17% |
Global Warming Potential (CO2 kg) | 37,047 | 46,826 | 9,779 | 26% |
Air Emission Index (index scale) | 8,566 | 9,729 | 1,163 | 14% |
Water Emission Index (index scale) | 17 | 70 | 53 | 312% |
Solid Waste (total kg) | 13,766 | 13,641 | -125 | -0.9% |
ATLANTA DESIGN | Wood | Concrete | Difference | (% Change) |
Embodied Energy (GJ) | 398 | 461 | 63 | 16% |
Global Warming Potential (CO2 kg) | 21,367 | 28,004 | 6,637 | 31% |
Air Emission Index (index scale) | 4,893 | 6,006 | 1,114 | 23% |
Water Emission Index (index scale) | 7 | 7 | 0 | 0% |
Solid Waste (total kg) | 7,442 | 11,269 | 3,827 | 51% |
Another study conducted by the Canadian Wood Council compared the life cycle impacts of three 2,400 square foot homes designed primarily in wood, steel and concrete over the first 20 years of their lives. Relative to wood, the steel and concrete homes were predicted to:
- Release 24 percent and 47 percent more air pollution
- Produce 8 percent and 23 percent more solid waste
- Use 11 percent and 81 percent more resources
- Require 26 percent and 57 percent more energy (from extraction through maintenance)
- Emit 34 percent and 81 percent more greenhouse gases
- Discharge 4 and 3.5 times more water pollution
These differences may seem small until one realizes that only a small portion of the materials in a house (by weight) are involved in framing. One can expect the impacts to be many times greater when components made from different materials are compared directly.
Sources
- The Environmental Performance of Renewable Building Materials in the Context of Residential Construction
128K pdf
Consortium for Research on Renewable Industrial Materials (CORRIM), 15 pages - Energy and the Environment
426K pdf
Canadian Wood Council, 16 pages
More Information
- The Athena Institute
Offers the ATHENA® EcoCalculator for Assemblies, which provides free LCA results for more than 400 common building assemblies as well as its parent tool, the ATHENA® Impact Estimator for Buildings- EcoCalculator Fact Sheet 118K pdf
- Estimator Fact Sheet 118K pdf
- National Institute for Standards and Technology
Product-focused, offers the BEES® LCA software (Building for Environmental and Economic Sustainability) - Life Cycle of Wood Products
227K pdf
Canadian Wood Council, 1 page - Wood and Green Building: The Role of Life Cycle Assessment
901K pdf
Wood Promotion Network, 2 pages