A building system of a building including one or more memory devices having instructions thereon, that, when executed by one or more processors, cause the one or more processors to store a digital twin of the building comprising a graph data structure, the graph data structure comprising a plurality of nodes representing entities of the building and a plurality of edges between the plurality of nodes representing relationships between the entities of the building. The instructions cause the one or more processors to receive an modification to the digital twin of the building, generate a change feed event of a change feed, the change feed event recording the modification to the graph data structure, and synchronize, based on the change feed event, an external digital twin of the building of an external system with the digital twin of the building by communicating with the external system.