A normative decision analysis method for the sustainability-based design of products

This paper introduces a new normative decision analysis method for the sustainability-based design of products (NASDOP). It is based on the fundamental principles of normative decision-making methods for design optimisation when multiple and often conflicting criteria influence the design of products. A unique feature of NASDOP is that it enables direct consideration of both environmental and economic impacts during a design process. Furthermore, NASDOP takes full advantage of the enhanced life cycle assessment (LCA) capabilities, reflecting the increase in knowledge about the material and energy flows of various processes in recent years, and offers a methodical approach to account for the inherent uncertainty associated with such knowledge. This paper details the development of sustainability models, including the effective integration of LCA mathematical models combined with compatible life cycle costing models from the early stages of conceptual design for use throughout the entire design process. This paper also highlights the design and deployment of hypothetical equivalents and inequivalents method, a proven normative decision method, to consistently model the preferences of a designer during sustainable product design. The implementation and usefulness of NASDOP are demonstrated with the aid of an illustrative case study and the results are discussed.