A heat pump together with 28 borehole heat exchangers is responsible for heat generation. The pump supplies a buffer storage tank which feeds the concrete core temperature control (CCTC). The CCTC is divided into two control circuits (north and south) on each floor. In summer, the heat is extracted from the rooms via CCTC and released into the earth by means of the borehole heat exchangers. The heat pump is not in operation. The energy requirements for cooling and heating balance each other out - the temperatures in the soil therefore do not build up during the course of the year.
Fresh air is supplied on each floor via a central ventilation device with heat recovery. This allows the individual systems to be operated at an optimum and be adapted to the individual usage period. Outdoor air is drawn in via the roof and, through ceiling outlets, is fed into the offices via concrete-encased ventilation tubes. The air from the offices flows through the door leaves into the central zone which is used as an exhaust air section. The exhaust air returns to the outside via the heat exchanger in the ventilation device. The meeting rooms are equipped with hermetic doors and receive larger quantities of supply air. Here, the exhaust air is extracted by suction directly through ducts. The borehole heat exchangers' water circuit can also be used for cooling and heating the supply air by means of an additional heat exchanger. In consideration of the staff being present at the same time, the air renewal rate is reduced to the hygienically-necessary requirement of 20 m³/h per person.
The pipes for CCTC and ventilation were cast into the concrete ceiling together with the welded wire mesh. This is how the air ducts are also used for heat or cold recovery. At the same time, individual areas can be separated spatially and in a flexible manner.