Regrettably, buildings often do not perform as expected or wanted by the users. Especiallywith regard to indoor environment, dissatisfaction is occurring frequently. Based on aninvestigation of two office building projects, an analysis of causes for the mismatch betweenuser requirements/expectations and the performance of buildings and systems has been made.The investigation consisted of an analysis of the development of building and systems,based on documents and contracts, an interview of the building manager, an occupantquestionnaire, measurements, calculations and interviews with stakeholders.The early design stage (pre-design) and the handing over of the building are found to becritical for the performance of the building (including systems) with regard to indoorenvironment.Due to assuming a fixed user pattern of the building the chosen concept for the building andsystems often is not able to cope with changes during the use of the building. It is proposed toexchange this traditional approach for a strategic design concept, wherein flexibility of thedesign is the main goal.In the handing over phase, there is not sufficient monitoring of the functioning of theHVAC system, resulting in insufficient tuning of the system and late reaction onmalfunctioning. Automatic fault detection and diagnosis using a Building ManagementSystem could play an important role in the monitoring of the HVAC system.