As a result of the technological advances and increasing focus on energy efficient buildings, simple forms of building automation including automatic motorized blinds systems found their ways into today's office environments. In a five-month field study, qualitative and quantitative methods were used to investigate how office workers in 40 offices experience and use automatically controlled exterior venetian blinds with options for manual override and switching off the automatic mode. In total, 3433 blinds adjustments (average of 0.86 per office per day) were recorded, of which 73.6% was initiated by the user. Significant correlations between weather parameters and blind adjustments were found, including sunshine duration and user-triggered lowering of blinds (R=0.354), cloud cover and user-triggered lowering of the blinds (R=-0.281), and outside temperature and user-triggered raising of blinds (R=-0.266). Four blinds usage profiles were identified and the underlying motivations for the different users were described. In the majority of offices, the automatic mode was switched off.