Purpose: For optimising long-term building operations, building clients need to enable integration of operational knowledge in the design process of new buildings. This study aims to investigate and compare how operational knowledge is integrated into the design of buildings and large ships, focussing on the roles affiliation and the competences of the client’s project manager play. Design/methodology/approach: A cross-sectional qualitative methodology with multiple case studies (five cases) was used. In addition, ten expert interviews and two validation focus group interviews were conducted. Case studies included in-depth interviews, document analysis and observations. Findings: The study showed that organisational affiliation, focus and competences of the client’s project management play an important role in how much effort and resources go into ensuring integration of operational knowledge in the design process. In the ship cases, projects managers’ highest concerns were operations. Yet, the fewest procedures and tools to integrate operational knowledge in design were found implemented in these cases. Contrastingly, in the building cases, where operations were not the main matter of concern of project management, a large number of procedures and tools to integrate operational knowledge in design were implemented. Originality/value: To the best of the author’s knowledge, this research is the first to compare how integration of operational knowledge is taking place in the design process of buildings and large ships and identifying what these industries can learn from each other. Furthermore, it adds to the limited research on operations in large ship design.