Located at Vienna’s Franz-Josefs-Bahnhof, AQ1 Althan Quartier Francis transforms a late twentieth-century railway station into a contemporary mixed-use urban district while retaining the architectural value and embodied carbon of the existing structure.
The project by Delugan Meissl Associated Architects and Josef Weichenberger Architekten demonstrates how large-scale regeneration can prioritise adaptive reuse over demolition, balancing environmental responsibility with changing urban requirements. Rather than replacing the station complex, the intervention builds upon its structural logic, creating a more permeable and publicly accessible neighbourhood centre.
Adaptive reuse as a sustainability strategy
The project's primary environmental strategy is the retention of the existing reinforced concrete structure, based on the original design by Austrian architect Karl Schwanzer. Instead of demolishing and rebuilding, the intervention strips the building back to its sculptural load-bearing frame, preserving substantial embodied carbon while allowing the architecture to be reconfigured for contemporary use.
The removal of the original mirror-glass façade opens the building visually and physically to Julius-Tandler-Platz, improving daylight penetration, creating new public spaces, and strengthening connections between the railway station and the surrounding city. This approach demonstrates how structural reuse can reduce material consumption while extending the lifespan of existing urban infrastructure.
Densification within the existing urban fabric
Rather than expanding horizontally, AQ1 achieves additional capacity through carefully integrated vertical densification. Two new upper storeys are set back from the existing façade line, allowing the additional volume to merge discreetly into the surrounding cityscape while preserving the character of the original building. Internally, two new atria are inserted within the existing structural grid, bringing daylight deep into the building while improving natural orientation and spatial quality. Because the original prefabricated concrete system follows a clear modular logic, these interventions could be implemented with minimal structural alteration, reducing both construction waste and embodied impacts.
High-performance envelope and public connectivity
A new high-performance façade replaces the outdated enclosure with contemporary composite window systems, mullion-transom curtain walls, and rear-ventilated stainless-steel façade panels, improving thermal performance, durability, and long-term maintenance while preserving the building’s modern architectural expression.
At ground level, the station becomes a central public connector. New pedestrian routes link Althanstraße, Nordbergstraße, the station concourse, central courtyard, and the newly created urban terrace, transforming what was once an inward-looking transport building into a more open civic destination. Retail, offices, residential units, public amenities, and services are organised around these interconnected public spaces, supporting use throughout the day.
