Most services and products are designed in response to the needs, desires or expectations of humans. A variety of methodologies grouped by the term Human-Centred Design (HCD) have been deployed to formalise and improve this process, ranging from user-centred to participatory practices. However, the approaches’ consideration is primarily limited to individuals in their respective space and time. To examine these system boundaries in detail and address potentials for adaptation, this paper reviews dominant HCD methodologies, categorises them and highlights their respective characteristics. Further, concepts and methodologies from related fields are studied for potential contributions to HCD. This results in a proposed re-definition of the system boundaries of HCD by integrating spatio- temporal impacts on humans through an extended social, environmental and economic scope. The different studied approaches and varying impact assessments are exemplarily applied to the case study of urban mobility, in particular human-centred, scenario-based design approaches. However, the described methods and concepts are kept generic to ensure the applicability across various domains of design practice.