Embodied carbon emissions benchmarks of residential and commercial reference buildings in the United States

Buildings are responsible for 40% of global emissions. Embodied carbon (EC) emissions, or the emissions associated with the extraction, manufacture, use, and disposal of materials, represent 13% of global emissions, signifying an important priority for decarbonizing buildings. Despite its high global emissions, EC remains underrepresented in research, policy, and design relative to operational energy and carbon. EC benchmarks, which provide reference points for emissions in building construction, are a critical tool for quantifying and comparing the EC emissions of ‘typical’ building construction. This dissertation explores the central research question of ‘What are the EC emissions of representative archetypal buildings in the US?’ by establishing theoretical, science-based benchmarks for key US building typologies.This dissertation proposes and implements a methodology for defining theoretical, science-based benchmarks through the use of material quantity takeoffs, deterministic life cycle assessment (LCA), and probabilistic LCA. The benchmarks proposed in this dissertation represent the three most commonly constructed building typologies in the US: single-family residential, commercial office, and multifamily residential apartment buildings. The scope of the LCAs conducted herein primarily account for a building’s foundation, core, and shell, and consider both cradle-to-gate and cradle-to-grave emissions. The key metrics associated with these benchmarks are deterministic material use intensity (MUI, kg/m2) results and both deterministic and probabilistic embodied carbon intensities (ECI, kgCO2e/m2) representing different building designs, LCA tools, and building typologies. This dissertation also considers biogenic carbon storage and whole-life energy and carbon emissions.Chapter II is an investigation of the literature pertaining to EC benchmarking efforts globally and it summarizes the limitations of existing benchmarks. Chapter III establishes MUI and cradle-to-gate ECI benchmarks for single-family residential buildings. Chapter IV extends this analysis to a cradle-to-grave scope, as well as whole-life carbon and whole-life energy impacts. Chapter V applies a cradle-to-grave analysis to commercial office buildings, while also addressing design variability by modeling structural material choices and lateral loading scenarios. Chapter VI develops benchmarks for multifamily residential apartment buildings, and features parametric design that accounts for material quantity variability. Chapters III, V, and VI each consider uncertainty and variability in embodied carbon coefficients.Findings reveal that EC results are highly dependent on building typology and design parameters, such as primary structural material, substructure type, and bay size. Deterministic cradle-to-gate ECIs range from 39 to 121 kgCO2e/m2 for single-family residential buildings, 114 to 337 kgCO2e/m2 for commercial office buildings, and 89 to 715 kgCO2e/m2 for multifamily residential buildings. Each chapter details critical differences in ECI per material, building design, and LCA tool. The probabilistic LCA results underscore the variability in LCA data and enable comparative statistical analyses.This dissertation establishes a replicable framework for establishing theoretical EC benchmarks for buildings in the US. These benchmarks provide a foundation for building emissions comparisons, policy development, and stock-level analyses. The underlying methodologies enable future updates and expansions to the scope of this study to test alternative design strategies and new LCA data.