The rental space is composed of two sub-areas:

• Primary space: All areas available for direct office use (offices and warehouses).
• Secondary space: All corridors, stairwells, restrooms, kitchenette as well as other surfaces that do not represent the actual usage purpose.

The rental space calculation is generally made up of two principles:

• The norm of the German Institute for Normalisation (DIN), the DIN277.
• The standards for the calculation of rental space for office space (MF-B) of the GIF (Society of Property Researchers eV).