Passive Buildings Canada and Builders for Climate Action released their Emissions of Materials Benchmark Assessment of Residential Construction (EMBARC) report last week. Their data relies on 503 as-built homes from three typologies—single detached, semi-detached, and townhouses—that produced material carbon emissions (MCEs) totaling 20,122 tons. The mean across the set was 40 t CO2e per housing unit with a range from 9.5 t CO2e to 827.1 t CO2e.
If these results are extrapolated to include the 16,400 new homes built in the Greater Toronto and Hamilton Area (GHTA) each year, the result would be a total of MCEs of 840,000 t CO2e, roughly the equivalent of the emissions from 183,000 automobiles. The study's authors note that this is a gross underestimate of the total MCE for these three building typologies due to the exclusion of MEP equipment, appliances, finishes and more, and that the real annual cost in MCE may be closer to 1,750,000 t CO2e.
The authors strike a positive chord, however, by writing that modest substitutions for “best available materials” could reduce heated floor material carbon intensity and result in reductions of 573,000 t CO2e fewer emissions annually. These materials are defined as widely available, affordable, and code-complaint. If all buildings were to use the “best possible materials,” which is far less feasible, the reduction would be closer to 1,065,000 t CO2e annually.
To read the full report, click here.