Functional Unit Definition Criteria in Life Cycle Assessment and Social Life Cycle Assessment: A Discussion

The definition of a Functional Unit (FU) is essential for building and modelling a product system in Life Cycle Assessment (LCA). A FU is a quantified description of the function of a product that serves as the reference basis for all calculations regarding impact assessment. A function may be based on different features of the product under study, such as performance, aesthetics, technical quality, additional services, costs, etc. Whilst the FU definition is typical in LCA, this does not seem to be a common practice in Social Life Cycle Assessment (S-LCA), even though a FU definition is required. Unlike LCA, where quantitative data are mainly collected and processed, the assessment of the social and socio-economic impacts in S-LCA is based on a prevalence of qualitative and semi-quantitative data, a fact that renders the assessment to be somehow unfriendly. Moreover, whilst in LCA a product-oriented approach is typical, S-LCA tends to be a business-oriented methodology, where the emphasis of the social assessment lies on the behaviour of the organisations that are involved in the processes under study rather than on the function that is generated by a product. Indeed, several S-LCA case studies were found in the literature in which the FU is not discussed, let alone defined. The objective of this article is to contribute to analysing the criteria used for the definition of a FU in LCA and verifying whether these criteria can be suitable for S-LCA case studies applications. For this reason, a literature review was carried out on LCA in order to identify whether and how this issue has been tackled with so far. In addition, a second literature review was performed in order to verify how the FU has been introduced in the framework of the S-LCA methodology. Finally, an investigation of the analysis results, in terms of the selected FU, is proposed in view of an ever-growing need for a combination of the LCA and S-LCA methodologies into a broader Life Cycle Sustainability Assessment (LCSA).