User behaviour is increasingly being seen as the major determinant of ‘performance gap’ in buildings. This study is using a modern University hall of residence building occupied by a highly heterogeneous student population; here, we would expect to see user behaviour driven performance gap to appear. The case study building is a newly built, £70 million student hall of residence building complex in Southampton, UK; the complex consists of three individual buildings of varying size that together provide 1104 rooms. A post occupancy evaluation (POE) was undertaken in the building which included an online questionnaire survey and environmental monitoring. The questionnaire, carried out at month 5 of their 9 month stay, asked occupants about the environmental conditions in their room and the use of controls to change their indoor environment. A total of 223 responses were gathered of which approximately 26% were non-UK students. The environmental monitoring was undertaken in 80 student rooms and involved measurements of air temperature and relative humidity for this period. This paper analyses students’ reported use of indoor environmental controls regarding window opening and indoor space heating, and compares their responses to the environmental measurements. The results highlight the diversity in the reported use of the available environmental controls within rooms with similar typological characteristics. The potential reasons for the different levels of user control (as reported) such as climate history and gender are explored. The paper provides insights into the impact of occupant behaviour on the energy performance of the newly built halls of residence.