Does the occupant behavior match the energy concept of the building? – Analysis of a German naturally ventilated office building

• Longterm monitoring data from an office building in Frankfurt, Germany, is taken.
• Behavior profiles give helpful hints for the interaction of occupants with buildings.
• Window opening times in winter are in 10–25% of the days too long.
• Window opening in summer was 10–40% of times not supporting the building concept.
• Windows were still opened in summer when it was outdoors warmer than indoors.

Experiences show that there is often a large gap between the predicted energy demand and the consumption once the building is in use. One cause could be that the occupant behavior might not fit with the energy concept and cause counterproductive behavior. This paper is based on simple statistics as well as logistic regression analyses in order to evaluate how much the occupants interact with their building in a manner suitable to the building concept with natural ventilation. As case study, monitoring data from an office building in Frankfurt, Germany, is taken. The findings show that behavior profiles of window opening give helpful hints regarding the interaction between building and occupants. The window opening times in winter are in 10–25% of the days too long. The window opening in summer are in 10–40% of the times not supporting the building concept due to windows being opened while the outdoor temperature is higher than the indoor air temperature. These non optimal behaviors could be linked directly (by experts and occupants) to an increased energy consumption in winter. In the summer case, prolonged window opening at high outdoor temperatures does not lead directly to a higher energy demand, because no cooling system exists. However, the increased heat gain leads to a higher demand for night ventilation, which in some cases is facilitated by an electrical fan. In such a way, the auxiliary energy demand can be increased.