Approach to qualify decision support maturity of new versus established impact assessment methods-demonstrated for the categories acidification and eutrophication

Initiatives like the EU Product Environmental Footprint have been pushing the discussion about the choice of life cycle impact assessment methods. Practitioners often prefer to use established methods for performance tracking, result stability, and consistency reasons. Method developers rather support newly developed methods. As case studies must provide consistent results in order to ensure reliable decision-making support, a systematic approach to qualify decision support maturity of newly developed impact assessment methods is needed. A three step approach referring to key aspects for decision maturity was developed which takes the established life cycle impact assessment methods as a benchmark. In the first step, the underlying models of the methods and their respective differences are analyzed to capture the scope and detail of the characterization models. Second, the considered and available elementary flows covered by the methods are identified and compared to reveal consistent coverage, respectively, gaps between alternatives. In the third step, neglected elementary flows are evaluated with regard to their potential impact to the particular impact category. Furthermore, the characterization factors of concurring elementary flows are analyzed for significant differences in their shares. The developed approach was tested for LCIA methods for eutrophication and acidification in Europe. A systematic and practical qualification of decision support maturity can be achieved by a three-step approach benchmarking model scope, quantitative and qualitative coverage of elementary flows for new methods with established ones. For the application example, the established CML-IA method was compared with the ReCiPe method and the method of accumulated exceedance. These models vary regarding subdivision of environmental compartments, consideration of fate, as well as regionalization of characterization factors. The amount of covered elementary flows varies significantly as CML-IA covers about 28 more flows within the category acidification and about 35 more flows within the category eutrophication compared to ReCiPe and accumulated exceedance. The significance of all neglected elementary flows for the categories eutrophication and acidification is significant and represents a gap of up to 80 %. Furthermore, it was shown that the shares of some concurring elementary flows differ significantly. The introduced approach allows the benchmarking of newly developed against established methods based on application-oriented criteria. It was demonstrated that significant differences between the methods exist. To guarantee reliable decision-making support, newly developed methods should not replace established ones until a minimum level of decision support maturity is reached.