Relying upon sociotechnical analysis of technology in organizations, space occupation studies, and the sociology of organizations, this paper investigates the dynamics of appropriation of space and equipment by the occupants of a high-performance tertiary building, the adaptation of equipment by the building operator, and the effects on energy performance. Through an ethnographic qualitative survey, we analyze the dependencies between occupants, operators and managers associated with the use and the adaptation of the building and its equipment. Our analysis shows that the dynamics of appropriation of technologies and occupied space have decisive effects on the functioning of the system, comfort experience and energy performance. The learning dynamics of users and operators can overcome some misfits between building design, space occupancy and operation practices, but the persistence of misalignments hinders energy optimization and comfort experience. Organizational structure and the subcontracting of building operations contribute to this misalignment, while organizational reconfigurations through informal cooperation remain limited.