To renovate or to reconstruct – A comparative life-cycle assessment study over an existing building in Fribourg, Switzerland

This study presents a simple and agile yet holistic comparative assessment of the impact, in terms of non-renewable cumulative energy demand (nrCED) and global warming potential (GWP), of two envisioned scenarios for the future of an existing administrative building located in Fribourg, Switzerland: its demolition and reconstruction versus its in-depth renovation. Based on our set of hypotheses, results show that over all life-cycle phases (construction and operation) and the building’s lifetime, the renovation scenario’s GWP is 540 kgCO₂-eq/m² lower than that of the reconstruction scenario, corresponding to a 50% savings. In terms of nrCED, the difference is of about 2 MWh/m², a 45% savings in the renovation scenario. Both scenarios are found to comply with the SIA 2040 target values. These results, including findings on the most impactful elements, provide useful quantitative information for the decision-making and design team in their next steps toward defining the project.