Uncertainty in Quantification of Material Use and Embodied Greenhouse Gas Emissions of Single-Family Dwellings

Abstract

Reducing embodied greenhouse gas (GHG) emissions in the construction of buildings is globally recognized as important for meeting climate targets. However, quantitative understanding of building material use is limited and employing material efficiency strategies to reduce building embodied and global GHG emissions is underutilized. This dissertation advances the understanding of building material intensity (MI) and embodied GHG intensity with specific focus on single-family dwellings (SFD). The thesis examines the uncertainty and variability associated with current and practical approaches to built environment industrial ecology and building regulations, the variation in MI and embodied GHG emissions within and between cities, and the potential for material efficiency strategies to reduce embodied GHG emissions in SFDs. The three central chapters build an evidence-based approach to advance understanding of MI in SFDs and then combine MI with material GHG intensity to investigate embodied GHG emissions. Chapter 3 investigates variations in MI and implications for uncertainty in MI research focusing on buildings within one city (Toronto, Canada). Chapter 4 expands on this and examines differences in MI both within and between places with investigation of buildings in Toronto, Canada, Perth, Australia, and Luzon, Philippines. In Chapter 5, embodied GHG intensity is estimated and examined to determine whether the observed ranges of MI or material GHG intensity drive overall embodied GHG emissions of buildings. Three design and material strategies (light-weight design of structures, more intensive building use, very low GHG material substitution) are evaluated for their potential to reduce embodied GHG emissions of housing construction. Through the study of 80 buildings across three locations, this dissertation identifies important implications of uncertainty and variability within and between locations, determines implications of functional unit selection on interpreting MI, and identifies large contributors and drivers of building material use and embodied GHG emissions. The findings support uncertainty examination in bottom-up MFAs and inform building regulations on the use of functional units when developing benchmarks for building material and embodied GHG estimates. Material intensity and embodied GHG interventions for housing are location and context specific, but regardless of location, constructing smaller houses would reduce overall MI and embodied GHG emissions.