The office building at 20/36 Zollstrasse has been optimized from an energy and environmental perspective as part of a full renovation. The existing suspended façade was completely dismantled and replaced with a new ventilated suspended façade. The existing concrete spandrels and lintels were retained. Thermal insulation was installed at the spandrels to improve energy efficiency. The superstructures on the street-facing side and the courtyard side differ only in the cladding used on the substructure. On the street side, a natural stone façade was installed, while the courtyard side was clad with Eternit panels. The mansard-storey façade is made of metal with sheet-metal cladding on both the street and courtyard sides. The new aluminium windows are fitted with triple insulating glazing.
On the ground floor, a mullion-and-transom façade with full-height glazing was constructed. The distinctive front façade reflects the internal structure in the form of a vertical element with aluminium fins.
Like an elegant black dress, the spandrels are covered with “Palissandro Nero” natural stone. This stone was polished and applied across the entire surface to create a horizontal balance with the aluminium fins, while also giving the façade a playful, light, and textile-like appearance thanks to its milled and grooved surface. The projection awnings in warm tones add a lively touch that creates a welcoming atmosphere both on the street side and inside the building. The building was renovated in accordance with the Minergie-ECO label requirements and the cantonal sustainability standard.