Exploring Circular Strategies to Extend the Life of Existing Buildings

This report from CSA Group highlights the advantages from an LCA standpoint of deep-retrofit vs. demolition and new construction.

The authors conducted a literature review on existing research, standards, guidelines and building life-cycle assessment (LCA) case studies. As expected, retrofits had significantly less up-front carbon emissions when compared to tear-downs, however the long-term emission reductions were comparable.

Reflecting on this research, the authors point out some key issues with the methodology of past studies, before presenting their own findings from a Canadian LCA case study. The key takeaways were as follows:

1. Deep green retrofits achieve the same post-construction level of annual operating carbon emissions as demolition and new construction. Deep green retrofits also result in lower whole-life carbon emissions due to the savings from not rebuilding the structural system.
2. The case for retrofits is strongest in regions with green electricity, such as British Columbia, Quebec, Manitoba, and Ontario.
3. If new construction is required, it is beneficial to limit embodied carbon emissions by focusing on low-embodied-carbon materials, including low-carbon concrete and steel, and bio-based materials such as wood. Accounting for biogenic carbon storage in biomass materials can also support the case for building new timber buildings, since it can lead to similar whole-life carbon as retrofits. More analysis for calculating biogenic carbon is required.
4. Additional guidance and data are needed to link circularity and reuse principles to embodied carbon emissions and LCA benefits.