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

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