For applications of 3D city models such as simulating the impact of failures in supply networks, information on the city objects as well as on the supply networks are required. The CityGML extension UtilityNetworkADE allows for modelling different types of networks, the focus currently being on the representation of topographical and topological aspects. However, for representing supply and disposal tasks, also functional aspects are of relevance, in particular, when no detailed modelling of supply networks is available, but the impact of a failure on a certain region is to be analysed nevertheless. This paper presents three methods complementing the CityGML UtilityNetworkADE by functional aspects regarding the modelling of supply areas, the characterisation of city objects and network features according to functional roles and the representation of the potential and current supply of commodities to city objects.