Closed-loop sustainable product design for circular economy

Intensifying global consumption stipulates the use of sustainable manufacturing and circular economy concepts to make products while managing available finite resources. Designers must be equipped to design products considering the economic, environmental, and social impacts of the product life cycle. This paper explores product design in relation to sustainability and circularity principles, presents fundamental concepts, sets definitions, and proposes a new methodology to incorporate these two principles. This new methodology synthesizes elements of design for sustainability and circularity. The primary stakeholder categories are updated to explicitly include "society-at-large"-a neglected category in typical manufacturer-focused sustainability evaluations. Sustainability elements based on the total life cycle approach, including triple bottom line, life cycle perspective, 6Rs, and perpetual resource flow, are integrated with the circular design elements of resource conservation, product-life extension, and circularity compliance to create the novel closed-loop sustainable product design methodology. The metrics-based product evaluation framework presented compels designers to integrate sustainability and circularity elements in the designed products. Sustainability concerns of the product life cycle are evaluated for both negative and positive impacts to identify the value created for all primary stakeholders (i.e., manufacturers, users, and society-at-large). This methodology promotes a holistic view of the product life cycle, including end-of-life activity planning, leading to a perpetual resource flow. Performance influencing parameters available for designers are also examined, including the overlooked "dedicated" and "incidental" process-induced types, providing a strong basis for future research on product sustainability predictive models.