Is energy-efficient building sustainable? A case study on individual housing in Canada under BCESC energy updates

Life cycle thinking and holistic sustainability assessment are missing in current building energy codes globally, with primarily focus on operational energy use and greenhouse gas (GHG) emissions. The overall objective and originality of this study is to evaluate the building-level life-cycle environmental and economic impact of building energy code compliance, exploring the trade-offs between energy savings, various environmental impacts and cost effectiveness, taking the British Columbia Energy STEP Code (BCESC) as a case study. An integrated approach of using building information modeling (BIM) with whole building life cycle assessment (LCA) and life cycle costing (LCC) is proposed, and comparisons of life cycle environmental and economic impacts are studied with respect to each energy upgrade level. The findings revealed that while the total energy demand intensity and GHG emissions decreased (by about 50% compared to base scenario) with the code intervention steps, the other environmental impacts may increase due to the embodied materials, production, and upkeep of the upgrades, for example, the ozone depletion potential increased by nearly 800% compared to the baseline. Additionally, the energy-saving measures reduce building operating costs by about C$4,000, which is significantly less than the increased costs in other stages. However, this incremental cost does not always mitigate the effects of specific environmental impact categories. The findings will be of interest to building industry policymakers to develop more holistically sustainable building energy policies, allocating limited funds in a more cost-effective manner to reduce environmental impacts, instead of focusing solely on direct and temporary benefits.