Retrofit "Fruchtkasten", Herrenberg, Germany


The “Fruchtkasten” with its half-timbered facade and imposing wooden structure dates back to 1684 and is one of the oldest buildings in Herrenberg's old town.
The former harvest store is to be renovated in the next few years. In the fall of 2018, the municipal council passed a resolution in principle, and the "green light" for the preliminary design was given in July 2021.
The basic structure of the historic construction is to be preserved. The interior will be designed in a large air compound, is to appear translucent and light and draw attention to the historic structure. Two new essential elements, the “cube” and the “sky ladder”, are deliberately added to provide a modern contrast. The cube will provide space for exhibits across all floors and act as a connecting element, as will the sky ladder. It will open up the “Fruchtkasten” along a visual axis from the lowest floor to the top under the roof.
The retention of the historic building fabric is a high priority. At the same time, it is essential to avoid heat loss and to provide the necessary heating energy from renewable sources. The design strikes a sensible balance between these two requirements.
The ventilation concept provides for a central ventilation system, with distribution via the centrally located cube. In this way, simultaneities of the building can be used sensibly and savings in system size can be achieved. Through the open, vertical connection of the floors, the air is transported upwards and centrally extracted, so that heat recovery can be realized.
The activated floor can be used for both heating and cooling purposes. Heating and cooling are thus based to a large extent on the radiation effect of the surfaces. This provides a high level of comfort and can be operated with low heating and high cooling supply temperatures.
Heating and cooling energy is provided by an electric heat pump connected to a GeoCollect system that uses heat from near-surface geothermal energy. To ensure security of supply, a secondary system in the form of a gas condensing boiler is provided.