FRANZ Badenerstrasse

Werner Stücheli’s high-rise is a special orthogonal building block standing in the trapezoidal urban system. To integrate the high-rise in the urban mesh we adopted a strategy that can be read in a variety of ways, while still preserving the exciting tension of the urban design situation. The two existing geometries of the place become the central structural element of the design, which is concretely perceptible inside the building in the tension between the geometry of the courtyard and the perimeter facades. Along the street projecting slabs, one above the ground floor, the other below the rooftop storey tie the volume together, articulate the building in the vertical, and establish relationships to the scale of the adjoining buildings. To complement the volumetric composition of Stücheli’s building a striking end facade is made on Badenerstrasse. The existing facade of the high-rise is being gently renovated, with the aluminium panels reused, and updated to the latest standards in building physics.

Following the demolition of the existing commercial structures, to increase the internal density a new building is erected that quite clearly makes more intensive use of the site. The grey energy contained in the existing building is lost for the most part, making it all the more important to create a robust and resilient new structure that not only optimises operating energy but also minimises the amount of grey energy used to produce the building. The structure should also have the typological potential to accommodate a range of different uses in the long term, as a flexible urban building block in the area of the five-metre-high ground floor.

These considerations lead to a structure made of wooden columns, wall panels, beams and slabs with bracing concrete cores, as well as a lightweight timber-clad facade. In the spirit of the circular economy the new building is conceived largely as a materials depot that uses grey energy-optimised construction materials and elements in a way that will allow them in the future to be used repeatedly for new functions. This is achieved by a design that consistently considers ease of deconstruction and, to the greatest possible extent, avoids the use of composite systems.

For the functions of supporting, insulating, and protecting renewable or natural raw materials are used wherever possible: for example, wood for the facades and loadbearing structure, mineral wool as insulation and lightweight construction for non-load-bearing interior walls. In the framework of an experimental approach, a holistic system is suggested that proposes the maximum reduction of grey construction energy and the integration of renewable resources at all levels.