Product lifetime approaches in life cycle assessments of circular economy

Abstract

Purpose Life cycle assessment (LCA) has been widely used to assess the environmental benefits of lifetime extension, a circular economy strategy for reducing product impact. However, although such LCA results are sensitive to product lifetime, the selection between existing lifetime modelling approaches has not been discussed so far. Therefore, this study aims to provide recommendations on the selection of suitable lifetime modelling approaches for LCAs of lifetime extension. Methods Three modelling approaches have been used to express product lifetime in the life cycle inventory and impact assessment: single values, a no-fixed value or a distribution. They are compared using two different illustrative cases of mattress remanufacturing and high-voltage electric motor repair. Typical questions that are answered with each approach are formulated, and recommendations are provided for suitable approaches to various LCA goals. Results and discussion LCA results with all three approaches can be used to compare a baseline to an alternative with lifetime extension. However, each approach answers different typical, more detailed questions. A modelling approach using single values is suitable for identifying hotspots and burden-shifting. Using a no-fixed value informs on the range of validity of the results and a quantified lifetime break-even value for lifetime extension to be environmentally beneficial. Finally, using a lifetime distribution over a population provides information on the spread and average change in environmental impact when lifetime extension is implemented over this population. Conclusions This diversity of typical questions demonstrates the importance of choosing the lifetime modelling approach based on the goal of LCA of lifetime extension. The most common approach with a single and fixed lifetime value cannot always be adequate for LCAs of lifetime extension. Recommendations Practitioners are recommended to define the goal of their LCA and select a lifetime modelling approach adapted to this goal. To support this selection, the study synthesises suitable modelling approaches for typical questions in public policy and business applications.

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