Renovation projects in social housing tend to focus on diminishing the costs of the renovation. An affordable solution is sought for an average household, thus assumptions are made about the residents' behaviour when calculating the energy performance of the dwellings. However, households have different needs and preferences, and therefore the actual use of the building can affect the achievement of the zero energy goals. In the Netherlands, until 2020, the calculation of the energy performance coefficient (EPC) was necessary to obtain building permission. The EPC was calculated based on standardised occupancy, and took into account the characteristics of the building envelope and installations. Furthermore, the EPV (energieprestatievergoeding, energy performance compensation in English) is an instrument used by housing associations and landlords to recover part of their investments in renovating social housing into (nearly) zero energy homes through a regulated increase in the rent, while protecting the residents from increase on their costs of living. In this research, we used a monitoring case study in the Netherlands to investigate the effect of assumptions made during design regarding occupants' behaviour, preferences, needs and lifestyle on achieving energy neutrality goals. The following questions are answered: What assumptions where made during the design of the building, and how do they differ from actual behaviour?, and what are the consequences of the behaviour for the performance of the building and for the EPV? The objective of this research is to determine the importance of design assumptions in the design and evaluation of zero energy buildings.

As the goal-setting in the European Green Deal is to reach carbon neutrality by 2050, great efforts have been put to improve the energy efficiency in residential buildings. As residential buildings are towards high energy efficiency, building envelopes are becoming better thermally insulated and systems are becoming more energy-efficient. Therefore, the role of occupants in the actual building performance is becoming more important. However, contradictions exist between the uncertainties caused by occupant behaviour (OB) and the over-simplified consideration of OB in building design. Therefore, this paper aims to present a state-of-the-art of how OB is represented in residential buildings. Through a literature study, this paper first reviews different occupant behaviours and how they are considered in the design and operation of high-performance residential buildings. Modelling methods are categorized by occupant activities. In addition, behavioural theories in the application of analysing building performance are reviewed. How the behavioural theories are integrated with state-of-the-art building technologies is outlined. Finally, challenges and suggestions for representing the interaction between occupants and buildings in the design and operation of residential buildings are discussed.