Life Cycle Carbon Assessment of Reinforced Concrete, Structural Steel, and Mass-Timber Buildings in Canada

Urban population growth drives demand for buildings, increasing carbon emissions. In recent years, the Canadian government has been encouraging renewable construction materials. However, comparative assessments of embodied carbon emissions of various building types across Canada are limited. This study addresses this gap by conducting a life-cycle carbon assessment of functionally equivalent three- and six-storey commercial office reinforced concrete (RC), structural steel (SS), and mass-timber (MT) buildings in Vancouver, Montreal, and Toronto, Canada, using Athena Impact Estimator for Buildings (IE4B). Excluding biogenic carbon, MT reduces Global Warming Potential (GWP) by 33–36% and 27–32% for three- and six-storey buildings compared to RC in phases A–C, and by 14–19% and 5–14% compared to SS, respectively. Including phase D and biogenic carbon, MT reduces GWP by 99–102% and 109–118% for the three- and six-storey buildings compared to RC, and by 99–105% and 118–139% compared to SS, respectively.