How Multi-Criteria Decision Analysis (MCDA) is aiding Life Cycle Assessment (LCA) in results interpretation

Life Cycle Assessment (LCA) is a robust methodology that assesses the environmental impacts of product systems. However, assessing its outcomes is not always easy. When decision-making must be carried out in such complex situations, Multi-Criteria Decision Analysis (MCDA) may be applied. In this paper, the way in which MCDA techniques are being applied within the LCA context to aid results interpretation was assessed. The aim is to investigate the current framework of this integration and to map the application of MCDA and LCA according to the LCA steps, references and criteria. Thus, a research was made in SCOPUS and Web of Science databases through a specific set of key-words. As a result, 109 papers were identified. The survey demonstrate that MCDA is applied at three different times in LCA steps: at Life Cycle Impact Assessment (LCIA) to analyze trade-offs between impact categories, damage categories, or the LCA score with other dimensions; at the Life Cycle Inventory (LCI) step, to interpret aspects from inventory (such as waste generation); and at the Goal and Scope definition step to identify impact categories and aspects of LCI. MCDA is also used for LCIA development, to attribute significance to impact categories. In general, the Triple Bottom Line (TBL) dimension was more recurrent, followed by Environmental and Eco-efficiency (environmental-economical) dimensions. The most common criteria were global warming, acidification and eutrophication in environmental prisms, costs and profits in economic aspects and job creation and labor security in social aspects. Results have shown mutual benefits and a clear and growing interest from the scientific community in relation to MCDA/LCA. Specific subjects to be further studied are: MCDA supporting other methodological choices, such as the allocation approach; MCDA to elicit meanings for impact categories in a way to compel stakeholders and verify geographical conditions for decision-making, and; Economic and social criteria used may contribute to Life Cycle Costing and Social LCA development.