Assessing whole life carbon impacts of retrofitting Canada's 19th and early 20th century homes towards net-zero.

The ongoing climate crisis provides a unique challenge within the residential sector to reduce greenhouse gas emissions by 2050 in response to Canada's net-zero goal. Although legislation has been put in place to address the decarbonisation of the existing housing stock, the challenging goal set by the Canadian government requires action beyond current energy guidelines. This poses a difficult challenge regarding the retrofit of housing built in the 19th and early 20th century. The extensive retrofit needed to bring these houses to the highest level of residential sustainability may counteract the idea of national zero-carbon when considering embodied carbon. This paper seeks to evaluate the whole-life carbon impacts of implementing deep retrofits in 19th and early 20th-century Canadian homes using the EnerPHit standard. To achieve this objective, the study compares whole-life carbon emissions under a non-retrofit baseline and a retrofit scenario that adheres to the EnerPHit standard, focusing on homes in Southern Ontario. HOT2000 Energy simulation software was used to assess the operational energy consumption, while One Click LCA was used to evaluate the whole life carbon of the two scenarios. This study found that the deep retrofit resulted in a 60% reduction in annual operational emissions compared to the baseline scenario. The whole-life carbon assessment further demonstrated a 48% reduction in total emissions over a 60-year period, with a carbon payback period of 6.8 years. These results imply that adapting this retrofit strategy would be beneficial to meeting Canada's 2050 net-zero goals, as the operational energy savings are superior to the total embodied carbon associated with the retrofit strategy.