Methods for managing uncertainly in material selection decisions : robustness of early stage life cycle assessment

Abstract

Utilizing alternative materials is an important tactic to improve the environmental performance of products. Currently a growing array of materials candidates confronts today's product designer. While life-cycle assessment (LCA) methods provide quantitative input into this selection decision, their implementations are evolving and disparate. The goal of this paper is to explore several major analytical variations of LCA implementations and the implications of these variants across a range of application contexts. Specifically, this thesis examines analytical variations in valuation method and treatment of recycling by exploring allocation methods that affect product end-of-life. An abstracted case study across a range of materials is presented, including materials that exhibit a spectrum in variation of environmental performance and material degradation between primary and secondary applications. To date, research has shown that the amount of recycled material delivered by, or used in, the life cycle of a product will affect the environmental burdens of other product life cycles. However, explicit consideration has not been given to the question of whether end-of-life allocation methods can lead to different materials selection decisions in early stage product development cycles. Similarly stemming from this question is the issue of, if so, how do these allocation methods differentially favor certain material classes? Results indicate that the choice of analytical method as well as its underlying parameters can have substantial impact on individual metrics that determine environmentally preferred material and that there are sets of analytical variation over which strategic results are strongly affected.