Reviewing allocation approaches and modelling in LCA for building refurbishment

With a growing building stock and initiatives such as the European "renovation wave" which aims to double the annual energy renovation rates in the next ten years, environmental assessment of building refurbishment becomes still more important. Using standardized environmental assessment methods such as life cycle assessment (LCA) on renovation projects is important to keep impacts low, and avoid burden shifting. However, a specific methodological challenge in refurbishment projects is how to include the existing building materials in the assessment. The aim of this study is therefore to present and characterise different existing allocation approaches for LCA in refurbishments. Furthermore, the study highlights advantages and disadvantages of the analysed approaches from an LCA practitioner's view. A literature review was conducted to find studies that illustrate the different allocation approaches and modelling of the existing materials in refurbishment projects. The approaches characterised in the study include allocation using 50:50, avoided burden, product environmental footprint (PEF), burden-free (and semi-burden-free), residual value or depreciation, and adjusting for past production of existing materials. The implications for LCA-practitioners were evaluated based on the work burden required for application. Here, the main cons relate to the large workload connected to modelling the existing building.