According to SIA 416 (ordinance of the Swiss Institute of Engineers and Architects), net floor space (Nettogeschossfläche - "NGF") is the part of the overall floor space (Geschossfläche - "GF") lying between the perimeter walls and the interior construction elements.

Net floor space is categorised into usable space (Nutzfläche - "NF"), transit or access space such as corridors (Verkehrsfläche - "VF"), and functional space (Funktionsfläche - "FF").