2. The method according to claim 1 further comprising generating the HFM graph in an eXtensible Markup Language (XML) format.
1. A method of using a Heat Flow Model (HFM) graph for detecting HVAC system faults for a building comprising: translating formal HVAC system descriptions from a Building Information Model (BIM) for the building as HFM nodes; retrieving HVAC component attributes from the BIM for each HFM node; retrieving predefined HFM nodes from an HFM node library that correspond to the BIM for each HVAC equipment type respectively; creating connectivity among the retrieved HFM nodes from BIM connectivity data; compiling the HFM nodes into an HFM graph; inputting real-time data from the building HVAC control system to the HFM graph for fault detection; detecting building HVAC system faults using node rules which are conditioned inequalities based on node specific configuration data that defines the functionality of a physical HVAC component; and mapping rule violations from the HFM nodes to the building HVAC control system failures.