This paper aims to identify suitable and energy-efficient luminous environments for two users sharing the same office and conducting various activities at the same time (paper and/or computer-based work, meeting with a visitor). The office is lit by daylight, controlled by an exterior shading system and by artificial light, composed of ceiling sources and a task lamp on each desk. In all, 930 subjects participated in six psychophysical tests conducted on the internet, each dedicated to a user position and an activity. Multiobjective optimizations were then performed with the collected data in order to identify luminous environments that realized the best tradeoffs between visual conditions for both users and power demand. An optimized luminous environment, judged suitable, whatever the combinations of activities in the room, is proposed.