Climate change impacts of recurring office fit-outs: a prospective life cycle assessment of circular economy-based improvements

Purpose Buildings with long service life are associated with recurring greenhouse gas (GHG) emissions arising from repeated activities such as refurbishments over time, which can significantly contribute to the cumulative climate change impact. In particular, multi-tenant office buildings, where fit-outs typically occur every 2–10 years, contribute approximately a quarter of GHG emissions over the building service life. This study applies prospective LCA (pLCA) to quantify the climate change impact over the service life of a tenanted office building and assesses the effect of circular economy (CE) strategies using time-differentiated analysis. In contrast to static life cycle assessment (LCA), this approach enables climate change impact assessment of future scenarios with changed processes to account for potential future emissions. Method An office fit-out case study in Aotearoa New Zealand was modelled using attributional LCA. The climate change impact was initially quantified using static LCA and hotspots were identified for applying CE strategies. Alternative CE strategies were then modelled using static LCA, related to maximising reuse, design for optimisation, and using low-impact materials. Then pLCA was conducted using the premise software to quantify the future climate change impact by analysing office fit-outs across four subsequent fit-out cycles at 10-year intervals, with and without implementation of CE strategies. In addition to the global future scenarios in premise , a national electricity decarbonisation pathway was included in the scenario modelling. Sensitivity analyses were conducted to assess the robustness to key assumptions in the evaluated CE strategies and use of alternative climate policy pathways. Results and discussion The static LCA results showed that office fit-outs in module B5 are dominated by GHG emissions arising from manufacture of materials and components. Implementing all the evaluated CE strategies can reduce the net climate change impact of a single office fit-out - modelled using static LCA - by 17%. However, when modelled using pLCA, the net climate change impact of the final office fit-out is reduced by 56% relative to the same office fit-out modelled using static LCA. Conclusion The study shows that pLCA enables a more comprehensive evaluation of future GHG emissions associated with recurring fit-outs in office buildings, and the future mitigation potential of CE strategies that target current GHG emission hotspots. Through the incorporation of prospective background data, the results capture potential future technological, socio-economic, and climate policy developments that are not represented in static LCA.