A system of perimeter corridors creates a buffer zone, separating the stacks climatically from the rest of the building and the outside walls. Thanks to constant air humidity of 50% (+/- 5%) and a temperature of 18° Celsius (+/- 2°), the climatic conditions in the stacks are perfect for preserving paper documents.

Each of the five storeys of the closed stacks is divided into eleven compartments to prevent a possible fire from spreading right across it. Furthermore, electrical fittings in the stacks have been reduced to a minimum and all vital technical components are installed outside the stacks to reduce the risk of a fire being caused by a short circuit, for example. Lights and sockets in the stacks only become live when there is a member of staff in the room.

The closed stacks are also adapted for the collections that they house. Posters, maps, portraits, etc. are kept in specific cabinets. Older, more sensitive documents are packed in acid-free storage boxes and stored on shelves.