This work presents the results of a study on user behaviour and building systems in an office building in Kosovo. The main objective of the project was to observe and analyze indoor climate conditions as well as occupant’s behaviour at workspaces, and to find measures to enhance the building’s thermal performance and efficiency. In the study of the thermal performance of the office building, indoor data loggers were used to monitor events and states in seven offices over a period of six months (from December 2008 to June 2009). Events and states such as occupancy, temperature, relative humidity, illuminance and status of electrical fixtures were recorded every 15 minutes. The recorded data were processed and analysed. Based on the results from the research, the interaction between occupants and building systems was found to affect thermal comfort and energy use of buildings. Therefore, it is necessary to have accurate information about user control behaviour in office buildings in order to improve building performance and energy consumption. These behavioural patterns can be used to develop a basis for evaluating the influence of occupancy on building energy consumptions, building simulation programs and intelligent system control strategies.