Supply versus use designs of environmental extensions in input–output analysis: Conceptual and empirical implications for the case of energy

Input–output analysis is one of the central methodological pillars of industrial ecology. However,the literature that discusses different structures of environmental extensions (EEs), that is, thescope of physical flows and their attribution to sectors in the monetary input–output table (MIOT),remains fragmented. This article investigates the conceptual and empirical implications of apply-ing two different but frequently used designs of EEs, using the case of energy accounting, whereone represents energy supply while the other energy use in the economy. We derive both exten-sions from an official energy supply–use dataset and apply them to the same single-region input–output (SRIO) model of Austria, thereby isolating the effect that stems from the decision for theextension design. We also crosscheck the SRIO results with energy footprints from the g lobalmulti-regional input–output (GMRIO) dataset EXIOBASE. Our results show that the ranking offootprints of final demand categories (e.g., household and export) is sensitive to the extensiondesign and that product-level results can vary by several orders of magnitude. The GMRIO-basedcomparison further reveals that for a few countries the supply-extension result can be twice thesize of the use-extension footprint (e.g., Australia and Norway). We propose a graph approachto provide a generalized framework to disclosing the design of EEs. We discuss the conceptualdifferences between the two extension designs by applying analogies to hybrid life-cycle assess-ment and conclude that our findings are relevant for monitoring of energy efficiency and emissionreduction targets and corporate footprint accounting.