A critical review of S-LCA methods since the UNEP, 2020 guidelines: lingering challenges in the search for standardization

Abstract As the least researched component of holistic Life Cycle Sustainability Assessment (LCSA), Social Life Cycle Assessment (S-LCA) continues to face significant methodological fragmentation—hindering the integration of social dimensions in sustainability research. Despite the methodological consolidation efforts provided by the landmark 2020 United Nations Environment Programme (UNEP) Guidelines, several challenges remain. To lay a foundation for greater coherence in S-LCA, this study conducts a critical review of 30 case studies published since the 2020 UNEP Guidelines to evaluate both emerging practices and enduring limitations. From this, four key methodological gaps are identified: (1) lack of transparency for rigor and replicability, (2) macro-scale approaches with generic data inhibiting contextualized analysis, (3) data availability limitations, and (4) need for more effective application of qualitative methods. To address these challenges, the review offers future directions, including enhanced documentation protocols, adoption of micro-scale boundaries enriched with high-resolution data, and shifting application of databases. Additionally, its discussion highlights the importance of high-fidelity data and collaboration with corporations, alongside qualitative method applications adherent to social science principles. These insights inform a flexible framework that builds from existing standards and guidelines to support rigorous, context-specific S-LCA implementation across diverse sectors and micro-scale applications.