Stepwise guidance for data collection in the life cycle inventory (LCI) phase: Building technology-related LCI blocks

Life cycle inventory (LCI) data gathering is one of the most time-consuming and data-intensive tasks in life cycle assessment (LCA) studies. Until now, it has mainly been described at a theoretical level and is associated with non-specific guidelines in LCA reference documents, thus leaving LCA practitioners with limited guidance prone to inefficient, not transparent, and sometimes inconsistent steps taken in the LCI phase. To tackle this problem, a stepwise data collection guidance is developed based on a critical review of existing guidelines and LCA case studies published in peer-reviewed scientific journals. The guidance encompasses three steps: (i) planning of data collection, including the outlining of LCI blocks, which represent unit processes in an aggregation level that is technology-wise appropriate; (ii) data gathering using the LCI blocks; and (iii) LCI blocks finalization. A customizable, generic LCI template for data collection is provided to facilitate the conduct of steps (i)-(iii). A real-life data collection case of lithium-ion batteries manufacturing is used to demonstrate the guidance's applicability. LCI block datasets were produced using the customized LCI template and the proposed guidance. Cooperation with the case data provider thus enabled to fill the data collection template, which was then reviewed iteratively. Although this case evidences the guidance's operability and its benefits in facilitating and strengthening LCA practice, several constraints undermining reproducibility and transparency could be identified, in particular issues related to data confidentiality. Despite these limitations, which require further efforts from practitioners and more transparency from stakeholders involved in the commission of LCA studies, the authors call for applying the proposed stepwise guidance to enhance future LCA practice.