The attention to sustainability impacts arising during the lifecycle of products is growing as industry wants to increase its contribution to a sustainable society. To do so, companies must find ways to navigate the complexity of the needs within the socio-ecological system in which they operate. In engineering design projects, the interpretation of needs into requirements is essential, as they represent the collective understanding of the design problem to be solved. Ideally, requirements are possible to verify and validate, which makes it challenging for industry to integrate socio-ecological considerations, often based on qualitative models, into requirements. Sustainability then tends not to be prioritized in trade-offs with traditionally identified requirements for engineering design.

A qualitative research approach within design research methodology framed a sequence of studies guided by the research question ‘How can requirements be utilized to support Sustainable Product Development?’ First, a research gap was identified from a literature review which indicated a lack of socio-ecological systems contextualization in the identification, as well as the traceability of sustainability criteria to integrate into requirements. Secondly, a conceptual model was established for how management of requirements can be improved to facilitate traceability, as well as how contextual socio-ecological systems perspective can be introduced in the selection, of sustainability criteria for engineering design projects. For this purpose, the results from a multiple-case study based on semi-structured interviews with seven design and manufacturing companies was triangulated with findings of an in-depth literature analysis. Five key elements of management of sustainability in requirements were proposed in a profile model corresponding to different levels of sustainability maturity. A third study explored, based on literature and prototype causal loop diagramming, the potential of a group model building approach to enhance contextual understanding of strategically identified, i.e., company-tailored, sustainability criteria in relation to traditional requirements in early phases of the product innovation process. A final study investigated how a strategic sustainability perspective can be integrated with engineering design methods and value modelling to create a decision support for concept selection.

The studies together indicate that key constituents of good requirements, traceability and systems contextualization, can be achieved also for socio-ecological sustainability considerations. This requires organizational commitment and will be reflected in the design of the operational management system for their product innovation process. Following the proposed five key elements of sustainability integration in requirements, a company is expected to increase the organizational sustainability maturity, and hence its capability to contribute to a sustainability transition. This research also shows that there is a gap in current methods and tools for enhanced socio-ecological systems contextualization. The two last studies of this thesis give promising approaches of tools and methods to be further developed and analyzed, namely group model building, system analysis and value modelling.

Product development companies’ attention and desire to contribute to sustainable development is growing fast but requires new capabilities. The socioecological systems constitute a complex landscape of operating conditions from which product development identify needs for new products. Correct needs interpretation is essential to ensure that the requirements that the needs are transformed into do represent the shared understanding of the design problem that is to be solved. However, companies find it challenging to integrate sustainability into requirements. Socioecological criteria therefore tend to be down prioritized in trade-offs with traditionally identified requirements for engineering design.

This thesis asks the following question: “In which ways can decision-making practices for requirements development and management support sustainable product development?” and aims to provide deeper knowledge to academia and support product development companies that wish to advance their contribution to sustainable development. A mainly qualitative research design using exploratory, descriptive, and prescriptive studies clarifies the research gap, and proposes and evaluates novel approaches to improve the state of knowledge and practice. These research studies are represented by the seven publications within this thesis. The first was a systematic literature review on current methods and tools for sustainability integration into requirements. Thereafter followed a multiple-case study with semi-structured interviews at seven Swedish product development companies. A model of five key elements of sustainability integration in requirements was proposed, which in a third, focus group case study with four companies, was developed into, and tested as, a self-assessment tool. The results were discussed in relation to theory on requirements engineering and sustainability design criteria, which emphasized that companies lack capabilities to contextualize requirements development using wider sustainability- and systems perspectives. Decision-makers responsible for requirements weighting need to anchor sustainability as a value driver which requires transparency and traceability in decision-support. A fourth study therefore explored sustainability integration in value modelling for concept selection, and a fifth study proposed an approach to guide sustainability criteria development following requirement characteristics. The sixth study proposed an approach to inform requirement analysis through improved systems contextualization, transparency, and shared understanding of sustainability in relation to other design objectives. Finally, the seventh study provided an outlook and initial discussion to guide the identification of value drivers on a macro-level in society which could leverage an increased uptake of sustainability-oriented requirements in product development

Altogether this thesis provides insights and approaches to guide companies to advance towards sustainable product development through the lens of requirements. Examples include key characteristics of, and principles for, identifying sustainability criteria and developing requirements using strategic sustainability thinking, as well as a support tool for guiding activities in different steps of the requirements development. The findings can also be used in education of future engineers and decision-makers, and for continued research.