This chapter describes some of the ways that demand for energy is made in hospitals. It develops an account of energy demand as the outcome of the organisation of connected working practices that constitute the regular provision of healthcare. Drawing on interview data taken from an ethnographic study of institutional rhythms and the organisation of working practices in hospitals, it describes how changes in the material arrangements, professional boundaries, and temporalities that underpin hospital life affect the fixity and flexibility of connections between practices in ways that matter for the potential for large institutions to achieve demand side response and to foster the design of new and less resource-intensive ways of working.