Harmonizing EPD and CBAM methodologies for carbon footprinting of power transformers

Two key instruments are the Environmental Product Declarations (EPD) and the European

Union Carbon Border Adjustment Mechanism (CBAM). EPD is voluntary and based on life cycle assessment (LCA), while CBAM is a policy-driven, trade-oriented carbon pricing system targeting embedded emissions in imported products. Although both instruments include the quantification of carbon emissions of products, their different scopes and methodologies introduce complexities for manufacturers striving to meet both voluntary and regulatory requirements.

This paper proposes a harmonized carbon accounting framework that integrates the methodological elements of EPD and CBAM through a detailed case study of a power transformer. The transformer was selected due to its high environmental impact, long life cycle, and relevance to international supply chains. This study aligns functional units, system boundaries, emission sources, allocation methods, and reporting periods of both mechanisms.

Areas of methodological convergence are identified, and where divergences persist, mitigation strategies are proposed to enable interoperable data and consistent emissions quantification.

The case study presented relies on secondary literature data and simplified assumptions and, therefore, it serves to demonstrate the proposed approach to boundary mapping and data structuring, rather than to provide a CBAM-compliant result for a specific installation.

Currently, transformers are not within the scope of CBAM; however, since the beginning,

CBAM regulation stipulated a potential scope expansion to more industrial goods. In addition, in recent policy communications, the European Commission has indicated that this expansion could take effect in 2028 and include power transformers. This anticipatory approach to electrical equipment is relevant given the growing demand for verifiable product carbon data in sustainable procurement and corporate sustainability reporting. By bridging voluntary and regulatory carbon accounting frameworks, the proposed methodology enables manufacturers, importers, and grid operators to prepare for evolving requirements in industrial decarbonization.