The 100-year-old Collège des Parcs in Neuchâtel has undergone extensive refurbishment and been extended to increase its capacity from 380 to 530 pupils. The project included the construction of a new school building on the north-western edge of the site and an underground double sports hall to the south of the main building.

The new four-story school building (29 x 14 meters), which replaces the old gymnasium, has a clear floor plan that divides it into four main areas: a central access core, two lateral classroom zones and an outdoor space in the shape of a balcony.

The load-bearing structure is based on a skeleton frame system of prefabricated reinforced concrete columns running along the facade and thin, cast-in-situ reinforced concrete slabs. Structural partition walls between the three interior zones provide bracing against horizontal loads. The balcony is designed as a separate unit with a vertical load-bearing structure of carefully jointed and stained concrete elements that provide its distinctive architectural character.

The new double sports hall has been constructed entirely below ground, its presence marked only by a single-story entrance pavilion. Siting it immediately in front of the main building meant that the existing retaining wall to the south of the plot could be kept with only limited additional bracing work. During the building works, the structural safety of the main building was ensured by pre-stressed underpinning.

The floor slab and exterior walls of the sports hall take the form of a waterproof concrete tanked structure. The slab above the sports hall is made up of 1 to 1.42 meter high prefabricated reinforced concrete beams laid out in a regular 1.69-meter grid with a span width of 16 meters. The factory-made prestressed elements were assembled using a mobile crane sited in the Rue du Parc and helped achieve optimum construction times. Prefabricated panels placed on the beams served as the formwork for the cast-in-situ slab above them. This layer ensures a connection to the beams to form a T-shaped load-bearing structure and guarantees the diaphragm action of the slab.