1. A computerized method for evaluating and reporting a cause of a performance change in a building management system, comprising: receiving, at a processing circuit, an indication of a fault for building equipment of the building management system, wherein the indication of the fault is directly associated with an indicator building object; receiving, at the processing circuit, a causal relationship model including the indicator building object and other building objects of the building management system, wherein the causal relationship model is an ontological model describing causal relationships between pairs of building objects, wherein each of the causal relationships is a directional relationship between a first building object and a second building object, wherein the causal relationship model includes an indication of a relationship direction and an indication of a relationship type for each of the causal relationships, wherein the indication of the relationship type identifies an effect of multiple possible effects that the first building object has on the second building object; and using the processing circuit to determine a root cause of the fault by traversing the causal relationship model, wherein the root cause of the fault is directly associated with a building object causally related to the indicator building object.