A CO2-neutral high-rise building at Letzigrund
A slender residential tower at Badenerstrasse 501-505 in Zurich will complete the architectural ensemble at Letzigrund stadium from 2027 onwards. The design proposal by Michael Meier and Marius Hug Architects has been the winning architectural study, commissioned by owner and project developer Allreal Generalunternehmung. Lüchinger+Meyer assisted the design team as façade engineers. The high-rise will offer 64 flats and commercial space on the ground floor, with a shared terrace on the building’s roof top. The red colour of the new building will corresponds with the neighbouring stadium.
An important objective of the competition programme was the sustainability aspects. An underground car park was deliberately omitted, as the high-rise residential building is centrally located and ideally connected to public transport. The new building also meets the requirement for completely CO2-neutral operation, which is achieved due to the extensive use of the façades for energy generation by means of photovoltaics. The jury explicitly acknowledges the careful planning of the building envelope: “The design implementation of the façade and volume is convincing and meets the increased requirements for a high-rise building. […] The differentiated response of the façade, which is covered with PV modules depending on the orientation, does meet to the very different conditions in all directions and at the same time manages to visually hold the large building volume together.”
The development of the façades is derived from the technical context and optimised in terms of the circular economy and minimisation of the CO2 footprint.
Structurally, the main façade with NO orientation is based on a fully unitized aluminium system with Heat Mirror insulating glazing and external wind-stable textile blinds. The opaque spandrel zone are clad with photovoltaic modules or reused glass units (“Re-Manufactured Glass”). Both are fully integrated into the prefabricated façade elements. The southwest-facing balcony façade features the same materialisation and is design wise derived from the main façade, but inserted between the balcony bands as a ribbon façade. The mainly opaque, south-east facing front façade is extensively covered with a rain-screen photovoltaic cladding. The well-used standard PV modules can be visually upgraded on the outside with cast-like glass with a minimal reduction in performance. On the rear side of the PV-elements, the use of re-use old annealed glass as a substrate is proposed to minimize the embodied energy of the modules.
Finally, we would like to quote the jury report once again: “The assessment committee recognises the careful elaboration of the façade design and the concise urban expression. The project has the potential to give this place a new identity.”
(Visualisations: Filippo Bolognese Images)
