A groundbreaking cooperative housing project in Winterthur, Switzerland, has garnered international recognition for its innovative approach to sustainable construction and community living. The residential building, known as House D, was recently awarded the prestigious Balthasar Neumann Prize 2025, with the jury specifically commending its large-scale implementation of reclaimed building components.
Designed by Pascal Flammer Architects from Zurich, House D represents the second major project by the Zurich housing cooperative "mehr als wohnen" (more than living), following their acclaimed Hunziker Areal development completed a decade ago. Located in Oberwinterthur on the site of the former Kälin & Co. AG company, the Hobelwerk-Areal has been transformed into a cooperative residential quarter over recent years. The development comprises five new buildings designed by various architectural firms, along with two repurposed existing structures, creating a living environment for approximately 400 residents.
House D stands as a four-story elongated structure positioned at the northern edge of the site, situated behind the old woodworking hall. The building is strategically framed by a lower existing industrial hall to the southwest and an eight-story new building by Ramser Schmid Architects to the northeast. The ground floor features a permeable organization with 3.6-meter-high residential studios designed for small businesses and craftspeople.
The building's innovative layout separates public and private functions across different orientations. Less private functions including circulation areas, studios, workshops, and commercial zones face the more visible southwest side, while the actual living spaces are oriented toward the northeast, each equipped with small garden strips directly outside their doors. On the west side, four apartments share a large workshop space, while the eastern section houses four additional through-units.
The three upper floors showcase a sophisticated cluster structure, with each level containing two apartments that can be connected when needed, plus a small guest apartment with its own bathroom. Access to the guest units is provided through a sculptural external spiral staircase made of concrete. The interior design continues the mixed-use concept, featuring three to four units per cluster, each with private bathrooms and one to three rooms, separated from generous communal spaces by long wall panels equipped with kitchen facilities.
What makes this project particularly noteworthy is its extensive use of reclaimed building materials, though this sustainable approach isn't immediately obvious to visitors. Working in collaboration with baubüro in situ from Zurich and Basel, the architects integrated reuse considerations from the project's inception. Windows, doors, corrugated metal sheets, and ceramic tiles sourced from former bank buildings and prisons were incorporated throughout the structure. The project operated under the constraint that costs of reclaimed materials could not exceed those of comparable new components.
This approach created what the architects describe as "pragmatic heterogeneity," unified through a subtle design strategy: all reclaimed components were treated with a thin coat of white paint without concealing their original characteristics. The construction methodology remained equally sustainable, featuring no basement, minimal concrete use limited to the circulation core, solid wood ceilings, and prefabricated wooden wall modules.
The building's facade varies between traditional wooden cladding and recycled metal sheeting, with the latter used where fire safety requirements demanded it. The project achieved remarkable cost efficiency with net construction costs of approximately 7.3 million Swiss francs according to the BKP 19 building cost plan. With 1,800 square meters of main usable area, the development achieves a living space consumption of 30.1 square meters per person, which falls below the Swiss national average, demonstrating that sustainable, community-oriented housing can be both environmentally responsible and economically viable.
