Building-Award 2021

On the Erlenmatt Ost site in the north of Kleinbasel a new urban quarter is developing. At its heart sits an abandoned silo, built in 1912 for the Basler Grain and Cacao Beans Dry Storage Company which is now converted into a multi faceted venue for the wider local community.
Now a new socio-cultural offer of different uses is created, which is accessible and can be experienced by everyone.
This includes ateliers and studios as an affordable space for cultural workers and young businessmen, as well as a hostel and a restaurant at the heart of the project. The overall aim is to create and promote diversity.
The originally free-standing silo building is now integrated into a row of buildings along the Signalstrasse. Its neighbors are a house for students and a residential and atelier building for artists. Noise pollution from the adjacent motorway, high sustainability goals and the internal spatial organisation characterize the project.

As one of the first steel-reinforced concrete structures in Switzerland with a unique spatial condition defined by a vertical division of spaces, our aim was to preserve and celebrate the genius loci. Throughout the design process the building’s inner structure was always taken into account, safeguarding as much as possible of the existing fabric of the building and keeping disruptive interventions to a minimum.

For this reason the characteristic silo chambers have been preserved. They give the building and its new use a familiar scale. The new functions are accomodated by the installation of only two new floor slabs and distribution cores. Porthole-like windows now provide ventilation, daylight and a view to the outside without affecting the original tectonics of the façade.
The guest rooms of the hostel are located on the 1st and upper floor on the street side. On the courtyard side towards the southwest, the studios are located on the 1st and upper floor. On the ground floor, the seminar rooms face the street and the restaurant opens up to the public courtyard with an outdoor seating area.

Extra structural/technical informations:

Old concrete buildings place high demands on engineers and architects. In most cases, the buildings no longer meet today‘s requirements for structural safety. One is inclined to subject the supporting structure to total renovation or even demolish it. Through close coordination of the engineering and architectural concept, an optimal solution was found, which reused the structure also with regard to the embedded CO2. The reinforced concrete structure of the silo could thus be largely preserved without having to carry out an expensive and surface-altering renovation.
The old reinforced concrete structure was inadequate with regard to three properties and did not meet today‘s requirements for a safe and durable building. The earthquake safety and fire safety were not sufficient for a change of use. Carbonation in the partially porous tamped concrete was also already well advanced. Concrete vibrators were not yet common during construction. This meant that localised corrosion of the reinforcing steel in the concrete could not be ruled out.

The concrete cover of the silo cells was also insufficient and did not meet the requirements in case of fire. Only the columns dimensioned for a high payload could serve for load-bearing safety during a fire. The new ceilings therefore only rest on the columns. In case of fire, the silo cells act as non-load-bearing elements and do not require fire protection.

New stair cores, which also serve as escape routes, were absolutely necessary for the new use. For this purpose, two silo cells at both ends of the building had to be dismantled. Together with the two inserted floor slabs, these cores now stabilise the building and serve as earthquake retrofitting. In accordance with the original use of the silo, the silo funnels were filled with lightweight fill. This also served as formwork for the construction of the concrete slab above.

The new cores also host the shafts for the new technical installations. Which are reduced to the absolutely necessary minimum thanks to the inertia of the exposed concrete structure. Only the Hostel rooms and the Restaurant are mechanically ventilated.
From the cores, the pipes run through the building, visible and separated from the primary structure. A heat pump connected to the district heating provides the heat supply and heat is transmitted by radiators. The building complies with highest insulation standards and combined with the mechanical ventilation system reaches an optimal efficiency.

With its 432 m2 of photovoltaic panels installed on the roof, the Silo is part of the largest energetically self-sufficient community in Switzerland. The whole district of Erlenmatt Ost runs by 100% energy produced from renewable sources and 70% of this energy is produced locally.

Das Silo Erlenmatt – einer der ersten Industriebauten aus Stahlbeton in der Schweiz – wurde zu einem Begegnungsort mit Restaurant und Hostel umgebaut. Neben den charakteristischen Kraftlinien konnte die Stahlbetonstruktur des Silogebäudes weitgehend erhalten werden, ohne eine teure und oberflächenverändernde Sanierung durchführen zu müssen.