Product stage embodied greenhouse gas reductions in single-family dwellings: Drivers of greenhouse gas emissions and variability between Toronto, Perth, and Luzon

Abstract

Reducing embodied greenhouse gas (GHG) emissions in the construction of buildings is increasingly recognized as necessary to meet medium- and long-term climate targets. The focus of efforts to reduce embodied GHG have been on using lower GHG intensity materials through material switching (e.g., wood vs concrete buildings) or changing the manufacturing of materials to reduce their GHG intensity (e.g., blast oxygen furnace to electric arc furnace in steel manufacturing). There has been much less attention directed toward the potential to reduce embodied GHG emissions by reducing the amount of material used for the construction of buildings. This study estimates the embodied GHG emission intensity of single-family dwellings (SFD) in Toronto, Canada, Perth, Australia, and Luzon, Philippines using a carbon neutral approach (excluding biogenic carbon) and focusing on the product stage (A1-A3). This examines the main drivers of embodied GHG emissions and quantifies the pathways to reduce embodied GHG emissions of SFDs. The mean embodied GHG emission intensities of SFDs vary across locations with differences driven by construction type and in upstream manufacturing of materials. The mean embodied GHG emission intensities in studied SFDs are 137 kg CO2 eq/m2 for Toronto, 190 kg CO2 eq/m2 for Perth, and 313 kg CO2 eq/m2 for Luzon. Monte Carlo simulation and principal component regression show that the variation in embodied GHG emission intensity within the studied cases is dominated by material quantities with less influence from material GHG intensity. Structural light-weighting, more intensive use of buildings, and very low material GHG factors collectively are shown to have the potential to reduce embodied emissions by 45%–60%. Strategies tested illustrated that savings on the order of 20% are readily available through more intensive use and structural lightweighting. Aggressive changes in energy sources and material manufacturing would take longer to achieve but could deliver another 22%–37% in emissions reductions.