Testing circularity measures: Lifespan and end-of-life modelling influence on the environmental impact of the EU residential building stock

The reduction of the environmental impacts of the building sector, either through a decrease in its operational energy consumption or the promotion of circular practices, is the target of multiple EU policy initiatives. While different modelling approaches have been proposed to quantify the environmental impacts of the EU building stock, limited knowledge is available on the sensitivity of these models to key parameters associated with circular economy measures. To fill this gap, this study aims at testing lifespan and end-of-life modelling choices to gain an improved understanding of their effect on the quantification of the environmental impacts of the EU residential sector, using a Life Cycle Assessment (LCA)-based building stock model developed by the European Commission – Joint Research Centre (JRC) as the reference model. Several options were explored in relation to parameters affecting the service lives of buildings and their components, along with their end-of-life pathways. A sensitivity analysis was also performed to evaluate the model's robustness when subjected to parameter changes derived from the literature. It emerged that, due to the prominent role played by the operational energy phase, environmental impact results at the stock level were not significantly affected by parameter changes, with the exception of the particulate matter impact category, which achieved >10% variations when simultaneously testing shorter finishing material service lives and lower incineration and recycling rates. Shifting the focus to embodied impacts, however, led to increased sensitivity in the model, with oscillations due to service life length overshadowing those connected to end-of-life treatment changes: in terms of single weighted score, the former can achieve a building-level variation of over 100% (when assuming short lifespans), while the latter does not exceed 38% (when maximising incineration rates). It is therefore necessary to take these fluctuations into account when using this LCA-based model as a basis for verifying the potential benefits of measures to promote circularity within the building sector, particularly as said measures primarily target embodied impacts.