Hybrid input-output analysis of embodied carbon and construction cost differences between new-build and refurbished projects

Abstract

Refurbishing buildings helps reduce waste, and limiting the amount of embodied carbon in buildings helps minimize the damaging impacts of climate change through lower CO2 emissions. The analysis of embodied carbon is based on the concept of life cycle assessment (LCA). LCA is a systematic tool to evaluate the environmental impacts of a product, technology, or service through all stages of its life cycle. This study investigates the embodied carbon footprint of both new-build and refurbished buildings to determine the embodied carbon profile and its relationship to both embodied energy and construction cost. It recognizes that changes in the fuel mix for electricity generation play an important role in embodied carbon impacts in different countries. The empirical findings for Hong Kong suggest that mean embodied carbon for refurbished buildings is 33-39% lower than new-build projects, and the cost for refurbished buildings is 22-50% lower than new-build projects (per square meter of floor area). Embodied carbon ranges from 645-1059 kgCO2e/m2 for new-build and 294-655 kgCO2e/m2 for refurbished projects, which is in keeping with other studies outside Hong Kong. However, values of embodied carbon and cost for refurbished projects in this study have a higher coefficient of variation than their new-build counterparts. It is argued that it is preferable to estimate embodied energy and then convert to embodied carbon (rather than estimate embodied carbon directly), as carbon is both time and location specific. A very strong linear relationship is also observed between embodied energy and construction cost that can be used to predict the former, given the latter. This study provides a framework whereby comparisons can be made between new-build and refurbished projects on the basis of embodied carbon and related construction cost differentials into the future, helping to make informed decisions about which strategy to pursue.