The engineering design process transforms stakeholders’ needs and desires into design specifications. In this process, manufacturers make decisions that impact how much value can be generated from a new product/service. Clear design specification can enhance the value of a product/service. This research study focuses on the engineering design process for systems of products and services - product-service systems (PSSs).

An unambiguous PSS classification could help manufacturers to produce clearer design specifications, however there is a lack of clear PSS classifications for engineering design. Existing classifications rely on an out-dated distinction between tangible objects as products, and everything else as a service, a division that inappropriately classifies digital products as services. To develop a coherent PSS classification, it is necessary to understand which characteristics of PSS can clarify its design specification.

This research addresses this problem by determining the PSS characteristics that are useful for clarifying the design specification. The research aims to develop a PSS characterisation scheme and explore how the scheme influences design specifications. To achieve these aims, case study and action research methods are employed.

This study has developed a PSS characterisation scheme that clarifies design specifications and a method to systematically apply this scheme, the PSS characterisation approach. This approach proves useful for practitioners to clarify design specifications, and has extended the application of the theory of technical systems to instruments supporting the engineering design process. The PSS characterisation scheme comprises four characteristics: customer perceived value level, ‘connectivity number’, type and degree of connectivity and configuration type. The scheme does not use the ‘tangibility’ distinction, but incorporates concepts of value creation and interdependencies within a PSS and between a PSS and its environment. This novel characterisation scheme contributes to the development of a PSS classification scheme for engineering design and also to the literature of PSS classifications.