Natürliche Belüftung eines Hochhauses mit Doppelfassade

Due to an increasing sensibility regarding environmental factors criterion like a decreasing energy consumption and emission problems become more and more important. In order to minimize the energy expenditure of a modern facade and to guarantee an adequate in-door-climate, new designs and developments are necessary. Twin-facade systems are representing an excellent attempt to fulfil these requirements. Using twin-face-facades it is possible to ventilate rooms in high rise buildings wchich are more exposed to wind loads using common windows and in turn reducing the time air conditioning will be necessary. A concept of a twin-face-system of the debis building for the Daimler Benz Project at the Potsdamer Platz in Berlin will be introduced. In model tests the ventilation rate of the planned twin-face-facade is investigated by simulating the thermal forces governing the phenomenon of natural ventilation. Ventilation rates for different flap configurations of the outer facade and different window openings are given. The investigations are showing that natural ventilation of the rooms even in cases of extreme winds or high solarization can be realized. Using the results of the model tests and the climate data of Berlin it is possible to evaluate the time when the twin-face-facade-system can be used for the room ventilation. By considering the average temperature and wind data it can be demonstrated that the time of operating the air conditioning plant can be decreased to a few weeks per year. The energy requirements of the planned building are decreased essentially.