Swiss garden cities are facing fundamental change, as existing frameworks (e.g. ISOS) fail to preserve them. We propose binding design principles in order to prevent demolition and guide transformation.

After its incorporation in 1934, Schwamendingen transformed from a farming village into an urban residential area between the 1940s and 60s. The number of residents increased from 3,000 to 34,500 between 1950 and 1966. The development followed city architect Albert Steiner's plan of 1948 based on the garden city concept by Ebenezer Howard. The goal was to create affordable housing for the working class, while leaving green corridors through the neighborhoods. All important facilities are near the center Schwamendingerplatz, where the main infrastructure axis comes together. Within the residential areas are small shops, community spaces, and schools.

Since 2016, Schwamendingen is part of the federal inventory of heritage sites of national importance ISOS and therefore undergoes structural preservation.

All across Europe, buildings built shortly after the Second World War in the garden city typology face the same fate, as they reach the end of their renovation cycle. Accordingly, with rents being low and pressure for renovation rising, present tenants see themselves challenged to stay.

In Schwamendingen, the only part of Zurich built in this typology, compared to the whole of Zurich:
Median income is 25% lower
Percentage of foreigners is 30% higher
Building activity over the last ten years is 600% higher
Average m2/person is 25% lower
Social benefits are received 200% higher

Today, Schwamendingen houses nearly 30,000 inhabitants in roughly 15,000 apartments. 53% are owned by cooperatives. It is transforming into a sought-after middle-class residential neighborhood.

With the train station Stettbach, the Glatttalbahn, and the highway enclosure, new developments started in large parts of the district. Cooperatives and investors have great interest in profiting from this new transformation boom and keeping Schwamendingen's character. In order to achieve this, they are supported by the City of Zurich, which is very concerned about the preservation of the garden city.

A big issue is posed by houses built between 1947 and 1956 which no longer meet today's standards. Specifically, energy consumption, poor building fabric, small apartment layouts, tiny balconies, and the lack of barrier-free accessibility.

The city-owned housing estate Luchswiese, built in 1961, consists of six houses in three rows and 15 garage boxes. Due to energetic reasons, a new facade, pitched roofs, and windbreak entrances were later added during renovations in 1981 and 1990. Around 150 residents live in 72 apartments ranging from 1 to 4 rooms. The 37m in between the buildings, being larger than required, allowed for 4 full stories for each building. With 28m2 per resident, the housing is slightly under the neighborhood's average of 33.6m2. Next to the plot is the school Luchswiesen, where the first three buildings were built in 1957 and two more in 2006.

In order to relieve the tight space conditions on the neighboring school Luchswiesen and the apparently too expensive renovation, the competition demanded at least 58 apartments, 4 kindergarten groups, and other school areas on the plot. Everything while keeping reasonable rents and the character of the garden city. These roughly 7,000m2 should use the plot's maximum aGF of 10,436m2 more efficiently than 4,560m2 of the existing buildings.

While 7 of 42 projects kept the existing, none of them were seen as really working. One of them got 2nd prize mainly because of the discussion about demolition vs. preservation. Read less