I’m working on low-rise residential benchmarking in Canada, and have completed a study of 190 models for the federal government, 34 as-built homes in Nelson, BC and 503 as-built homes in the Toronto region. We have been counting A1-A3 emissions for the structural, enclosure and main finishes (flooring, wallboard, ceiling) for the homes.
Depending on material selection, we’ve seen the as-built homes range from an average of 150 kg CO2e/m2 (of heated floor area) to 190. We’ve seen results as high as 560 and as low as 72. But with about 550 as-built examples it seems that the 150-190 range is a reasonable benchmark range.
Not sure how you’d want to turn that into emissions across 60 years, as we’re not counting any material replacements (we’re looking out between now and 2050 in these studies, and none of the materials we’re including should require replacement in that timeframe).
We’ve been recommending a metric of “carbon use intensity” that includes material emissions and operational emissions added together over a chosen number of years… usually to align with a climate target such as 50% reduction by 2030. In this way, we can steer designers and regulators to a single metric that ensures their targets are being met while not dictating how the home gets to that target, since depending on location it may be best to focus on energy source, energy efficiency or material selections, or some ideal blend of all three.
The reports are too large to attach here, but you can find them at Builders for Climate Action: https://www.buildersforclimateaction.org/
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