The conceptual approach of the project is that of an urban incubator integrated into the fabric of the city and identifying with the location in terms of construction, programme and building culture.
The urban planning strategy is informed by the surrounding buildings and works according to the principle of insertion and visibility. This applies both to the outer edges of the volume and to the height of the building, which is integrated into the topography of the environment while remaining a tangible and assertive new actor in the field. The building occupies the front and back recesses of Friedrich-Karl-Strasse and juts out from the first floor, making it visible from a distance. Towards the old market, the building frames the historical edge of the square and sizes the plot. The two-story administrative section of the rooftop greenhouse is situated within the ‘old’ plot. The main entrances of all three building programmes (catering, greenhouse and employment agency) give onto the square.
The greenhouse can be accessed from the square directly via the stairwell or by the cargo lift, which is used to deliver the rooftop harvest to the old market. This lift is also suitable for larger groups of visitors, taking them directly to the interior visitor and access corridor on the fifth floor. The employment agency can be seen from the visitors’ gallery through the large inner courtyard but is spatially separated. In addition, visitors can visit the entire greenhouse without having to enter a greenhouse. This allows for economic activity isolated from resources (heat, CO2, moisture) and prevents visitors from introducing germs into the greenhouses. Both employees and guided visitor groups enter the administrative part of the greenhouse through a door. An internal open staircase here connects all additional functions (training and other rooms, sanitary facilities) to the greenhouse level at a short distance. The work in the greenhouse can be seen live from the square.
The structure combines an administrative building and a rooftop greenhouse and is suitable for exploiting various synergies. In addition to the exchange of excess heat and cold, these also include the networked use of water and nutrients (CO2, sodium, phosphorus). Synergy optimisation is a key element of the energy concept. The two main pillars of this strategy are the use of the rooftop greenhouse and the atrium as ‘energy gardens’ and the storage of excess energy in a ballast storage tank in the basement