Energy use in buildings is closely linked to their operational and space utilization characteristics and the behavior of their occupants. The occupant has influence due to his presence and activities in the building and due to his control actions that aim to improve indoor environmental conditions (thermal, air quality, light, noise). Due to the demand for sustainable buildings more passive buildings will be built. Consequently the weight of the user behavior on the energy balance of a building increases. In the design phase, e.g., via building performance simulation, this effect has only recently been recognized. In this study the effect of user behavior on building performance has been evaluated further to assess requirements for design solutions to arrive at buildings that are more robust to the influence of user behavior. In the research two recent developments with respect to user presence and user interactions in a building have been combined. The results indicate that for specific buildings user behavior should be assessed in more detail, to allow the building design to be optimized for the actual user and its peculiarities. A guideline supports the decision process. (C) 2008 Elsevier B.V. All rights reserved.