Closing data gaps with emission factors: a general method applied to EPDs in Brightway

Purpose: Missing data are a fundamental challenge in Life Cycle Assessment (LCA). A promising way to address such gaps is the direct use of already calculated environmental impact assessments of upstream products. Although companies increasingly publish environmental information like Environmental Product Declarations (EPD), there is still limited research on integrating those emission factors directly as LCA results within standard LCA software to ensure seamless accessibility.
Methods: This paper proposes a novel method that integrates aggregated emission factors from environmental product declarations (EPD) into LCI. The method includes reverse calculation and proxy selection. Thus, proxies represent ecosphere flows which allow inventory result calculation and characterization during life cycle impact assessment (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: The feasibility of incorporating data without supply chain information in conventional LCA software is demonstrated. The developed 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 applicable.