Towards a mass balanced life cycle assessment database.

Life cycle assessment (LCA) is a crucial tool to guide decision making because of its ability to capture both direct and indirect impacts throughout the value chains. LCA studies often use the ecoinvent database to represent different activities and value chains in our economy. Ecoinvent contains fixed descriptions of processes and until now, the construction of these processes has focused on their linkages and on the impacts they cause. Mass is not systematically recorded for all flows and there is evidence that the conservation of mass is not respected. We propose a rebalancing algorithm which estimates the mass of all elementary flows and products in the different versions of the ecoinvent database by leveraging principles of material flows analysis (MFA). We aim to transform the ecoinvent database into a technologically rich MFA database. The algorithm reconciles fragmented data sources and ensures all activities comply with the conservation of mass principle.