The Préfecture du Rhône building is the administrative centre for the Rhône department, demanding a strong public presence. It replaces a previous building on a corner plot in the central Third Arrondissement of Lyon, the department's capital city. Its plan-form is straightforward with six storeys plus a set-back 'penthouse' and external roof areas, and a 2-storey basement.
Copper Clad Volumes
The two main facades are articulated as distinct, copper-clad volumes aligning with the typical Mansard-roofed blocks either side. The volumes are separated on the west front by an inset cloak of suspended stainless steel mesh reaching up to the penthouse and signaling the building's entrance. Copper was the architect's first choice and its sustainable credentials a consideration. Opaque cladding is generally pre-oxidised copper, selected for its more regular brown shade than 'mill finish' material.
The defining external features of the new building are vertical shutters clad in perforated, pre-oxidised copper. In conjunction with the suspended stainless steel mesh screens at street level, the perforated copper gives transparency - but the motorised, pivoting shutter arrangement also animates the facades. This brise soleil arrangement allows direct response to external conditions, controlling solar gain and glare, whilst maximizing potential for daylighting deep into the building. This strategy is thoroughly sustainable in terms of both environmental performance and choice of materials.
Environmental Control with Copper
The external copper shutters each pivot centrally and are operated in groups by electric motors, enabling local response to external conditions in combination with opening windows for ventilation. Even when closed, the shutters allow filtered natural light into the building and, at night, internal lighting transforms the building when seen from outside. The purely architectural impact of the design can be judged by comparison with the new facades before the brise soleil were installed.