This phase of the study involves compiling and quantifying the inputs and outputs of a product system that will have potential environmental impacts. The results can form the basis for the next study phase, or can establish baseline information on a syste m's resource requirements and environmental releases, and to plan for reduction. There is currently no consensus in the scientific community on which methods provide the best results. Classification qualitatively assigns inputs and outputs to categories based on environmental impacts. Characterization is a quantitative step that analyzes the relative contribution of the multiple inputs or outputs to an impact, to aggregate within a category based on equivalency factors.
Valuation is a subjective ranking of the relative importance of different categories.
Interpretation LCA Interpretation is closely tied to valuation, and entails weighing different types of environmental impacts against each other as the basis for subsequent decision making. This cannot be done without introducing political or social values. Ethical product system choice at the design phase or at the consumer level cannot be based solely on quantitative criteria. Numerous LCA methodologies have been developed, but none have yet become a normative standard. It is no small contribution that the LCA framework serves as a pedagogic tool for multi-disciplinary teams of designers, engineers, finance and environmental managers to affect environmentally sustainable product development.