How to choose the functional unit for agricultural LCA? A stakeholder-centered conceptual framework

A key methodological challenge in using Life Cycle Assessment (LCA) for agricultural decision support is the definition of the system’s function and functional unit (FU). In complex, multifunctional agricultural systems, this choice is often ambiguous and can significantly alter study outcomes, complicating the comparability and interpretation of results and posing a challenge for decision-making. To situate this problem, we first present a focused review of 34 recent LCA studies, which confirms the diversity of current practices and underscores the need for a more structured selection approach. In response to this identified gap, this paper develops a conceptual framework for selecting appropriate FUs. The framework includes a taxonomy that classifies agricultural functions according to key stakeholder perspectives: the consumer (product function), the producer (income function), and society (land management function). Building on this classification and the challenges highlighted by the literature review, we introduce five evaluative criteria: completeness, proportionality, specificity, stability, and accessibility. These criteria are designed to guide researchers and practitioners in selecting and justifying FUs that align with specific decision contexts. By shifting the focus from a single “correct” FU to a context-appropriate one, our framework provides a robust and transparent methodology to enhance the relevance and utility of LCA in supporting sustainable agriculture.