In Nanterre, in a diverse urban area composed of houses, housing projects, and industrial buildings, the Minimum-Security Prison, or CSL, and the Reintegration and Probation Services Center, or SPIP, have been joined to form a monumental enclosure and a symbol of the justice system in the Hauts-de-Seine Department. This represents a complex challenge: two programs must be organised on the same site whose workings are diametrically opposed. During the day, the SPIP supervises individuals on probation and helps them reintegrate into society. At night, the CSL houses prisoners on work release. For that matter, more than simply constructing a contemporary image of the justice system, the project must mobilise its urban potential to reinvent the disconnected stretch of land hosting the program. With a single volume, the SPIP building extends the row of the housing projects to the south and reinforces the corner of rue des Acacias and boulevard du Général Leclerc. It is set back from the street to allow for the installation of controlled entrances. The CSL is located behind this façade to preserve confidentiality.

Seen from the street, the building looks like a very dense parallelepiped with a two-storey opening in its façade that offers a distant glimpse onto the constructions situated in the middle of the block where the detainees are housed. In our collective unconscious, a prison is an impenetrable wall enclosing individuals whose only contact with the outdoors is a small piece of sky. The project does everything it can to undo this outdated typology by opening a large window onto the city and by providing new perspectives on imprisonment. Nevertheless, the need to prevent prisoners from looking towards the exercise yard was explicitly formulated in the technical specifications. Because it forms an inhabited enclosure that sits along the street, the SPIP looks out exclusively onto the public space and has no contact with the interior of the parcel. At the same time, the windows in the CSL cells face gardens in the eastern portion of the parcel that are only accessible to maintenance personnel. These landscaped spaces create a buffer zone between the exercise yard and the parcel’s enclosure. In addition to its ability to embody a certain number of characteristics typical of detention, such as the enclosure or the central courtyard, the establishment adopts a specific style such that it is neither fully a prison, nor simply a center that organises the collective life of the detainees.

The SPIP is covered with an initial skin of perforated sheet metal that mimics the effect of corten steel and provides both a visual screen and protection from sunlight. A second, thicker façade of load bearing concrete, exterior insulation, and a metallic covering ensures the envelope’s thermal performance. Folding, sliding shutters and the rhythmic variations in the perforations optimise the amount of natural lighting in the offices’ spaces. The CSL façades in direct contact with the detainees have a more robust sense of materiality, as they consist of a thick, washable concrete double wall. This choice forms part of a long-term strategy to limit operating costs. Other exemplary mechanisms have been implemented, such as heat recovery from used water and extracted air, as well as the site’s connection to the BMS to facilitate its maintenance.

Client: Ministry of Justice / Cost: € 11,18M excl. VAT / Surface: 3925 m² / Schedule: 2013–2019 / Batiserf Ingénierie (Structure), Nicolas Ingénierie (M.E.P.), Michel Forgue (Surveyor), Franck Boutté (HQE)