Investigating harmonization challenges in the EPD system: A Focus on EPDs Used in the Danish Building Sector

The Danish building code is imposing legislative restrictions to intensify efforts to reduce carbon emissions. This has increased the demand of environmental product declarations (EPDs). EPDs are expected to provide more accurate information and data on the environmental performance of building materials and components. The overall purpose of EPDs is comparability and they are thus developed in accordance with product category rules (PCRs). PCRs are published by program operators. Using four key program operators in the Nordic EPD system, this study analyzes the causes for inconsistency and their consequences in terms of differences in the results across the life cycle assessment (LCA) models underlying the EPDs. Two baselines and eight scenarios of LCA models were developed based on the guidelines provided by each program operator for the same product - a triple-glazed window. The results vary more than 10% from the baseline which is a substantial variation. The study further identifies that the program operators have no consensus on how to use and implement the core PCRs presented in the standards. Unspecific phrasing in EPD-related standards causes dis-harmonization, allowing the four program operators to act separately, hence contradictory to each other. Since several program operators publish PCRs, there is a risk of creating conflicting rules thus leading to inconsistencies. This can jeopardize the objective of comparability. Thus EPDs in their current system are not necessarily accurate. Further efforts must be made such that EPD comparability is achieved.