In the 1960s Georges Brera and Paul Waltenspühl built the Geisendorf primary school in the park of the same name, creating a loosely connected ensemble. Since December 2020 the new two storey structure complements the five existing pavilions along the site's northwestern border.
Similar to the blades of a windmill, four building wings surround a central space. The designs of all four facades are similar: They feature a transparent part with building-height facade posts consisting of pre-greyed larch and, set in between them, recessed glazing. This arrangement is balanced by large closed facade surfaces consisting of timber frame structures with larch siding. For the four load bearing walls in the interior, unfired loam brick found use, for the first time ever in Switzerland. It took altogether half a year to produce the material on site. Three workers extracted 110 m³ of stony loam from the construction pit, ground it, mixed it with 5 % cement and water and, eventually, moulded it into bricks by use of a mobile hydraulic press. Two months later, 22 000 bricks were stored on the old school yard, where they cured - gently and slowly beneath a layer of foil - for four more months. In the course of the "Chantier ouvert" summer program, the students themselves received the opportunity to help in the construction of their school and assist in the production of the loam bricks. In order to verify the load bearing capacity of walls, the masons first created three mock-ups that the materials testing laboratory of the EPFL in Lausanne used to conduct stress tests. The load bearing walls are built in cross bond and are set on top of a reinforced concrete plinth. Ash posts and lintels ensure uniform distribution of compressive loads. Only vertical loads impact the loam brick. In order to provide wall surfaces with homogeneous earth tone colouration, the lime-cement mortar for grouting joints received an admixture of loam. After completion, the walls were cleaned with a sponge. They reveal a silky sheen under the grazing light that passes through the facade glazing. The climate-related effects of the walls and their slightly earthen scent are just as pleasant. Similar to a sponge, they absorb moisture from the indoor air, retaining it until its delayed release. Although the bricks received an admixture of cement to enhance their load bearing capacity, the walls remain recyclable. Following demolition, the bricks can be ground and, after adding water, they can be re-pressed into new bricks.
The new building is occupied by students who can enjoy lunch in the two cafeterias and also participate in cross-curricular activities there. As a diverse district centre, it is also open to neighbourhood residents. Distributed across two levels, spaces are accessed by a central corridor that receives natural daylight through a large roof dormer and a glazed ceiling. Work and break rooms for the gardeners of the park are located on the ground floor with separate access from the outside.Outside school hours, the upper floor spaces are available to associations and bands can perform their rehearsals in the basement.
