A NEW STUDY BY THE CONSORTIUM FOR RESEARCH on Renewable Industrial Materials (CORRIM) confirms what building wonks have been saying for years: The choice of building material results in very different effects on air quality, solid waste, and resource use.
In the CORRIM study, researchers from 15 U.S. universities used computer modeling to estimate the total energy use for homes built using wood, steel, and concrete. They estimated the fossil fuel energy required (and pollutants released) in the production of steel-framed, wood, and concrete-walled homes. They also measured the energy required (for transportation, tool operation, etc.) on the jobsite. Not surprisingly, the impact of the former far outweighed the impact of the latter.
Jim Bowyer, a professor in the Department of Bio-Based Products at the University of Minnesota, helped organize the study. He notes that the hypothetical homes were designed to have similar energy efficiency when complete—an assumption that required adding significantly to the environmental impacts of the homes designed with steel and concrete.
“For example, Bowyer says, “a steel home would need to have external foam as a thermal break. And that product gives off significant emissions in the manufacturing process.”
The study concludes that building homes with wood releases far less emissions than steel-framed and concrete homes. It does, however, make one limiting assumption, which Bowyer acknowledges. It sets the average lifespan of a “typical” home at 75 years. Other recent studies by organizations such as the Athena Sustainable Materials Institute have found that homes may actually last much longer—closer to 150 years.
“That was a major bone of contention as we were planning the study,” Bowyer recalls, although he defends the choice, in light of this study's focus on the front end of the building process.
He adds that the next phase of research will address this discrepancy. Perhaps when a more accurate typical lifespan of buildings of different materials is better known, building scientists will be able to estimate more accurately just how important the pollution created at the manufacturing/construction phase is to a home's overall environmental pedigree.