It is possible to reach high accordance of the measured and simulated room air temperatures, when very detailed input data is available. Little differences i. e. in the user behaviour can alter the results significantly because the heat demand of the building is very small (ref. Table 1). An increase of the room set temperature from 20°C to 25°C increases, for example, the space heating energy demand by over 50% (with all other parameters fixed).

For detailed simulations and comparisons the user behaviour taken from standards is not sufficient. Even user profiles evaluated from questionnaires are sometimes not accurate enough (this is especially true for the ventilation by windows). Figure 2 shows the examples for the daily distribution of persons in the apartment and the electricity demand other than HVAC system chosen in this study.

Figure 2 Average daily distribution of persons in the apartment (left) and electricity
demand other than HVAC-system (right) (Streicher et al. 2004).