The site of the residential and office building Schlossberg isn’t exactly picturesque, despite being near the ruins of Castle Stein. Traffic rushes by along all sides of the building: express trains from Zurich to Bern or Basle as well as regional trains and local commuter trains. The Hauptstrasse 3, beginning in Basle and terminating in Bergell, crosses above the tracks. Thousands of cars frequent it each and every day. Street and railway tracks lead into two tunnels and through the hill. Their entrances are located right next to the new construction. Not to forget, the city bus lines 5 and 6 also stop here. The former frequents the inner city and traverses the sublevel of the new building. The latter exits the city through the structure’s ground floor. On the second sublevel an existing shopping mall intersects the building. Along the altogether three lower levels stores and services mix with public areas. The levels above are reserved for a doctor’s practice, office spaces and apartments. The project is highly complex in terms of organisation, planning and construction and combines residential and office uses, public functions and retail. While traffic is bustling around the building and diverse functions are stacked upon each other, it is remarkably calm in the interior. Similar to the calm eye of a cyclone.
The canton and the new building
The reason for creating a new residential and commercial building was a resolution of the canton of Aargau to liberate the historic city centre of Baden from all bus traffic and redirect the related bus lines. An existing building was in the way of the new traffic route, exactly where the new building stands today. It was clear from the beginning that the new street had to lead through the building and that a bus stop would have to be included in its interior as well. The owners, a group of heirs, decided to replace the existing building with a new structure. In 2012 the owners and the canton of Aargau, in public private partnership, held a competition. The canton supervised the project closely and contributed 20 % of construction costs. As a result, the architects had to deal with two clients, which didn’t make the planning of the complex project any easier. It comes as no surprise that four years of planning passed until groundbreaking took place. In the spring of 2019 occupants finally moved in.
A mesh of uses and levels
The new building occupies the same site as its predecessor. The route of the new street, its radii and the siting of the bus stops had already been established. This is why the ground floor features a triangular area for retail that was eventually occupied by a mobile phone store and a cosmetic studio. On the other side of the street, one level further below, the Schlossbergplatz offers a vivid urban meeting place that was redesigned in 2009. From the plaza, a pedestrian walkway leads underneath the new building and the railway tracks to the other side of the city. The main entrance of the residential and office building is situated on its north-eastern side. It accesses a physical therapy practice and the office spaces of a financial services provider, as well as the apartments on the levels above. In addition, the apartments received a second entrance on the south-western side, located on the first upper level and reserved for the residents. This is where the new building is connected to a massive bridge structure. It was built in the 1960s and is property of the Swiss Federal Railways.
The many points of contact with existing structures, the interweaving of different building levels, the city and its traffic network, the unique hillside topography and the way public areas intersect the lower building levels transform the structure into a vibrant place. It is all the more surprising how quiet it is along the residential and office floors.
Solid as a rock
The building withstands the hustle and bustle of city traffic with its robust facades made of prefabricated concrete elements. Where they face the old city, their design is restrained and calm, yet serrated and striking along the railway tracks. Here, eight duplex apartments with corner glazing offer views of passing trains and the ruins of Stein Castle. The two very different scenes are framed by large, double-height windows. Their panes have the highest sound transmission class rating currently available on the market. In Switzerland, strict noise exposure limits need to be maintained even if windows are open. Natural ventilation is compulsory, even if mechanical ventilation is in place, as is the case in this building. The architects met these requirements with their intelligent building section and floor plan design, in addition to the unusual means of ventilation they proposed. A patio cut into the building volume on the upper levels not only serves as an outdoor space, but also introduces light and fresh air into the deep floor plans. Initially the window casements were supposed to be equipped with automatic motors in order to open the windows from the inside. The motors were omitted due to cost concerns and the windows can only be opened manually from the outside. The lower floor duplex apartment plans are all similar. Apartment sizes vary on the upper levels. A long access corridor cuts through the building, the Rue Interieur. In front of the apartment entrances, it becomes wider and forms generous antespaces. It also connects the two staircases along the opposing ends of the building in a staggered zig-zag-pattern. Along the side facing the city, this pattern allows creating three smaller apartments. They offer a view of the northern 15th century gate tower. The tower and the ruins of Castle Stein are the two trademarks of Baden. There is likely no other building in the city that offers such diverse views and such diverse uses under one roof.
Building and structure
The structure of the building resembles a bridge. The existing underpass shopping mall that laterally traverses the building on the first lower level prohibited the placement of columns. The same is the case for the new bus lane that intersects the floor plan longitudinally. For this reason, massive concrete pillars transmit loads into the substrate at very few locations. The pillars feature haunches that reduce spans and serve as support for downstand beams. They measure 1.20 m in height and 40 cm in width and carry the three upper levels. A further challenge are the shocks caused by passing trains and the earthquake proofing that is generally required in Switzerland. Typically the solution would be to decouple structural components from the geological substrate through a soft insulation layer. Buses stopping and accelerating in the interior of the building also cause strong vibrations. The solution was to decouple the three lower levels from the upper three residential and office levels. The lower floors feature pin connections, the upper floors rigid connections. The connections occur between the downstand beams and the walls beneath them, interlocking in a sawtooth pattern. 75 mm thick elastomeric bearings separate the building components, hold them in place and prevent the transmission of vibrations into the upper levels.
User voices
Daniel Erne
Since April 2020 we are commercial tenants of one of the duplex spaces. Our six software company staff members are located here. The decisive aspects for us are the central location, the connection to infrastructure as well as the layout of the apartment with its private roof terrace. We enjoy using this outdoor space in particular during summer. Even though the train tracks run right in front of the building, the terrace can be used for a calm break. And the interior ensures a concentrated work environment. The tall windows provide ample daylight. Quite often during the summer months temperatures rise in the interiors. We did underestimate the reverb of the six metres tall spaces and the smooth office furniture fails to absorb it.
Christoph Landolt
The new building along Baden’s Bahnhofsstrasse has a very striking appearance. For our physical therapy practice it offers perfect ambience and a great advantage in terms of infrastructure. The connection to the city’s public transport and the proximity to the railway station were decisive factors for choosing this site. This benefits our patients in particular. When construction began we already registered for the future commercial spaces and profited from this early decision. As tenants we were able to determine the interior outfitting and apply our corporate design to the spaces. I am excited about the interiors and the ample daylight they receive. They provide a perfect room climate and offer a unique working environment. In addition, the roof terrace offers a panorama view of the surroundings and especially the nearby Schlossberg.
Ferris Bühler & Olga Cudakova
We moved from an historic building to the historic city centre of Baden. We’re happy that we now have shopping opportunities and access to public transport right in front of our doorstep. It takes us only five minutes to walk to our office. Despite being so close to the urban hustle and bustle, you hardly notice it when you’re on the inside. The roof terrace or the aquarium, as we like to call it, is an ideal open space for our family. It allows morning sunlight to enter our apartment. In the evening we enjoy the view towards the Schlossberg, framed by the window area that we also use as a sitting place. We very much appreciate the loft feeling and the lighting conditions of the apartment. We often use the apartment as a backdrop for our communication agency’s commissions.
