Embodied GHG of missing middle

Building form, CSBE news, Urban form


Residential building form and strategies for more efficient housing

In this paper, we quantify the impact of residential form on embodied emissions. Specifically, we look at the reduction potential of missing middle (low-rise multi-unit) housing, compare missing middle to single-family and mid/high-rise buildings, and identify opportunities for optimizing efficiency within forms. We find embodied GHG of missing middle buildings varying between 5540 and 39,600 kgCO2eq/bedroom. On average, multi-unit missing middle buildings have lower embodied GHG per bedroom than single-family and mid/high-rise buildings, but variability within forms is greater than between forms, indicating a large potential to reduce embodied GHG through building design. Best-in-class design strategies include reducing substructure size and indoor parking, limiting mid/high-rise slab thickness, and choosing low-GHG insulation products. Building missing middle homes in the 1st quartile of embodied GHG efficiency with minimum insulation emissions factors could reduce future embodied residential emissions in Ontario, Canada by 46.7%.