Buildings are independently usable, covered structures which can be entered by people and are designed or suited to give shelter to people, animals or things (Musterbauordnung from 11/2002). In the case of contiguous built structures (e.g. semi-detached or row housing), an individual building is defined as one which is separated by a fireproof wall or which possess its own entryway.

In the Monitor of Settlement and Open Space Development, building density and degree of building coverage are calculated using geo base data in the form of building footprints and coordinates. If a building footprint displays several structural elements, then these elements are incorporated into one polygon. The number of buildings is calculated from the number of resulting polygons. If a polygon possesses several addresses (house coordinates) then the number of buildings is determined from the number of separate house coordinates. Buildings with a footprint of less than 10 m² as well as built structures within a horticultural site (overlay with the ATKIS Basis-DLM) are ignored within Monitor.