Closing Data Gaps with Emission Factors: A General Method Applied to EPDs in Brightway

Purpose: Data gaps decrease the accuracy and reliability of Life Cycle Assessment (LCA). Although reported environmental data from companies could fill these gaps, they lack the processbased supply chain information required by common Life Cycle Inventory (LCI) databases. Instead of trying to integrate such process-based information, emission factors from environmental data can be directly integrated in LCA. This approach, however, requires in-depth understanding of LCA software and intensive maintenance, reducing user-friendliness. Methods This paper presents a userfriendly method that integrates aggregated emission factors from environmental product declarations (EPD) into LCI, demonstrating the feasibility of incorporating data without supply chain information in conventional LCA software. The method includes reverse calculation and proxy selection. Thus, proxies represent ecosphere flows to allow for inventory result calculation in the LCIA. The method generates LCI databases from emission factors with corresponding proxies, which provide these emission factors as LCA results within common LCA programs. Results and discussion The approach is demonstrated by integrating the ökobaudat (OBD) database – containing EPDs - into the LCA software Brightway. An example of LCA calculations with data from conventional and EPD databases using Brightway is provided. This example illustrates how data gaps can be effectively filled in a user-friendly way by simultaneously using data with and without supply chain information. Conclusions This method increases user-friendliness, as only one LCA modelling and calculation is required when using data with and without process-based information simultaneously. Additionally, the presented method is not restricted to a specific set of data sources, emission factors, or LCA programs and is generally valid.