Reviewing ISO Compliant Multifunctionality Practices in Environmental Life Cycle Modeling

TLDR

ISO 14044:2006 establishes a hierarchical framework for addressing multifunctionality in life‑cycle assessment, yet its practical implementation has been contested for twenty‑five years, producing diverse practitioner approaches. The study first surveyed how the ISO hierarchy is applied in 532 peer‑reviewed case studies via text mining, then used citation‑network analysis to trace key publications shaping the debate and uncover the origins of differing practices. These analyses yield recommendations for harmonizing allocation methods, emphasizing that consistent practices are urgently needed—particularly in bioeconomy sectors where multifunctionality is common and current approaches remain fragmented.

Abstract

The standard ISO 14044:2006 defines the hierarchical steps to follow when solving multifunctionality issues in life cycle assessment (LCA). However, the practical implementation of such a hierarchy has been debated for twenty-five years leading to different implementation practices from LCA practitioners. The first part of this study discussed the main steps where the ISO hierarchy has been implemented differently and explored current multifunctionality practices in peer-reviewed studies. A text-mining process was applied to quantitatively assess such practices in the 532 multifunctional case studies found in the literature. In the second part of the study, citation network analysis (CNA) was used to identify the major publications that influenced the development of the multifunctionality-debate in LCA, i.e., the key-route main path. The identified publications were then reviewed to detect the origins of the different practices and their underlying theories. Based on these insights, this study provided some “food for thought” on current practices to move towards consistent methodology. We believe that such an advancement is urgently needed for better positioning LCA as a tool for sustainability decision-making. In particular, consistent allocation practices could be especially beneficial in bioeconomy sectors, where production processes are usually multifunctional, and where current allocation practices are not harmonized yet.