The new extension of the Schubart-Gymnasium in Aalen, was designed as a zero-energy house. This means that based on a primary energy balance the new building will generate, at least, as much energy locally and renewably as the building uses in the course of a year. The balance sheet not only includes the building operations for heating, ventilation and lighting, but also the energy demands for user electricity.
Another special feature of this project is the holistic view of the exterior skin design. Detailed simulations have shown that the energy saving potential of additional insulation is relatively small, but the additional cost is very high. Therefore, no passive house standard has been realized. Furthermore, during the planning process the objective has changed from an initial passive house to an active house.
The developed climate concept includes a hybrid ventilation system that combines a mechanically supported ventilation with natural ventilation via operable windows. The amount of air supplied via a displacement ventilation in the classrooms is considered the basic requirement which is supported by opening the windows during breaks. The combination of the two strategies ensures an excellent air quality.
To optimize the ambient temperature in summer, the mechanical supply air is pre-conditioned passively via an earth duct. Effective night flushing via operable ventilation elements is also part of the climate concept. Upstairs skylights are provided, which are utilized for night ventilation and also bring daylight into the classrooms.
A cogeneration unit in a subsidiary building provides heat for the new extension wing. The photovoltaic system on the roof generates enough renewable electricity to achieve the objective of a zero-energy building.
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