A new paper on high-rise emissions

One argument for height limits and similar regulations is that high-rise apartment buildings generate more greenhouse gas emissions than low-rise apartment buildings, because the former category of buildings have more “embodied carbon”- that is, they use more energy-intensive building materials.

But a recent paper by some engineering scholars suggests that this argument is oversimplified. They suggest that emissions from “operational impacts” (for example, day-to-day electricity and natural gas use) are more significant than construction impacts. As a result, the article concludes that in Toronto, annual greenhouse gas emissions for new high-rise multifamily buildings are on average 24 percent less than low-rise multifamily buildings.

I note, however, that the study is inconclusive in some ways- most notably because it includes a fairly small number of Toronto buildings, and (perhaps more importantly) because its high-rise category includes all buildings in the sample that are over five stories. Thus, it does not address whether there is a difference between 5-10 story midrises and much larger buildings.*

*Readers might be wondering why the authors did not find enough buildings to make such distinctions. First, the authors chose to focus on post-2009 buildings, thus limiting sample sizes. Second, the authors’ data was based on an earlier study with a limited building sample.