Challenges and opportunities of integrating greenhouse gas emissions in building energy codes

•A workflow was developed to calculate building GHG emissions.•Embodied and operational GHG impacts of two residential archetypes are calculated.•More stringent building energy codes result in net GHG savings and short GHG payback.•Operational GHG emissions have considerable impact on life cycle GHG emissions.•Standardized procedures must be developed when GHGs are integrated to building codes. Understanding the challenges of estimating the GHG impacts of energy codes on buildings can help inform code committees on how they might integrate GHG emission data in building energy codes. This study provides this data by quantifying and examining the energy performance, embodied, and operational greenhouse gas (GHG) emissions for two low-rise residential archetypes across six climate zones, with each archetype meeting the criteria of the five energy tiers in the National Building Code of Canada. A workflow was developed encompassing code-compliant design selection, energy modeling, building information modeling, and life cycle assessment (LCA), and was tested on the case studies. The increasing stringency in the energy code reduces operational GHG emissions by 22–37% and marginally increases embodied GHG emissions by 3–8%. We have identified sources of LCA uncertainty, particularly spatial variability (climate, carbon intensity of electricity grid), parametric uncertainty (lack of localized material GHG factors), and variability in design choices (choice of heating technology), that can influence embodied and operational GHG trade-offs and the technical conditions in which GHG savings are met. This study identified recommendations for code committees including the development of spatially explicit material and energy GHG factors and province or territory specific code guidelines for reducing GHG emissions.