1. An apparatus for modelling causality in a flow system by means of a model devised to model components of said flow system and causal relationships between said components, wherein said apparatus comprises: a data storage means configured to store model element data related to said modelled components; a causal rule storage means configured to store a plurality of causal relations determining the causal relationships between said model elements; a state determination unit comprising a receiving means configured to receive from said flow system a status signal relating to a component thereof; an identifying means configured to identify said component related to said received status signal; identify a model element modelling said identified component; a determining means configured to determine an operating state of said identified component dependent on said status signal; and a processing means communicatively coupled to said data storage means, said causal rule storage means and said state determination unit, and configured to dynamically activate or deactivate a causal relation related to said identified model element and dependent on said determined operating state.