Product-Service System Designing for Environmental Sustainability : Insights into Design Cognition of Experienced Product Developers

Sammanfattning: The overall objective of this research is to support practitioners within the manufacturing industry to effectively design product-service system (PSS)-based solutions with relatively lower environmental impacts than typical product-centric solutions. Design research methodology (DRM) is applied to systematically address this objective with both descriptive and prescriptive approaches. The research draws empirical insights from a pool of 68 experienced product developers from the manufacturing industry. Initially, a generic model to predict the variant nature of domain-specific design cognition is conceptualized. Using this conceptual framework, differences in design cognition between conceptual product and PSS designing are theoretically predicted and empirically tested using protocol analysis. Based on a statistical comparison of the findings, the cognitive nature of PSS designing is descriptively characterized in relation to that of typical product designing. The results suggest that PSS designing is more problem-focused and applies a similar level of focus on the highest level of systems abstraction as product designing. A deeper investigation into PSS designing revealed that compared to product aspects, relatively less focus was afforded to the service aspects, interactions between product and service aspects, and the aspects regarding the overall PSS. Based on these findings, it was inferred that the cohort might need PSS domain-specific support to effectively design such systems. Three design support prescriptions were developed based on the improved understanding of the cognitive characteristics of PSS designing. One of these prescriptions, termed the PSS design schema, was developed using the method of literature analysis and synthesis. The other two prescriptions, termed lifecycle function deployment (LFD) and systemic lifecycle engineering, were developed using the method of action design research (ADR). Subsequently, the effects of the PSS design schema were descriptively tested using protocol analysis, and those of the other two prescriptions were assessed with a lifecycle assessment (LCA) of the design outcomes. The effects of the PSS design schema point towards significant changes in the cognitive characteristics of PSS designing. The effects of the other two prescriptions point towards significant reductions in the potential environmental impacts of the concepts when compared with the respective existing productcentric offerings that were redesigned using the support. Based on these empirical findings, the conceptual framework is refined and extended to conceptualize and hypothesize the interplays of pre-existing domain-specific knowledge of the designers and the effects of design support on design cognition.