Abstract

Maintaining the existing built environment is crucial to achieving substantial, near-term carbon and emissions reductions in the construction industry. Retrofitting existing building stock to avoid embodied emissions from new construction and upgrading and electrifying existing buildings reduces building operational emissions. For the buildings constructed between now and 2050, more than half of their emissions will be from embodied carbon. Estimates show that reusing and retrofitting the most carbon-intensive parts of buildings – the structure and envelope – can save 50% to 75% of the embodied carbon emitted by constructing similar new buildings. Yet, a significant challenge to adopting low-carbon building practices in deep energy retrofit projects is the complexity of calculating the embodied and operational emissions of proposed designs according to the needs and priorities of various stakeholders. Recently, tools for calculating buildings’ embodied and operational emissions have been introduced and are being rapidly adopted by industry stakeholders to aid decision-making. Yet, these assessment tools often produce significantly different results, depending on the assumptions and calculations used to weigh various factors. The varied and sometimes contradictory results create uncertainty for designers and building stakeholders throughout the design process, and a better understanding of the impact these tools and their assumptions have on the design process is necessary.