Fault Diagnosis of Air Handling Units

This paper presents an improved method for fault detection and diagnostics (FDD) of air handling units (AHUs). The fault detection module defines observable states of the AHU, where each state depends on current values of sensor data and control signals. The fault diagnostic module maps the observable states to the faults and then applies the cumulative sum chart (CUSUM) to define the size and development of each fault in time. The FDD method was tested on real datasets and its results were confirmed by the building technician. Finally, the method is compared with the standard APAR (AHU performance assessment rules) method developed by Schein et al.