Fault evaluation process in HVAC system for decision making of how to respond to system faults

One of the effective methods for energy conservation in buildings is to operate the building system with high efficiency and to reduce the waste of power consumption. However, buildings are often considered to contain faults, and a fault is one of the causes of hindering high-efficiency operation. Therefore, in a maintenance plan for building systems, it is necessary process that to detect and diagnose faults. In addition, an operation and maintenance process of building systems using fault detection and diagnosis (FDD) essentially requires evaluating the impacts of faults in order to decide how to respond to faults. However, many studies on FDD have not considered a fault evaluating process. Here we focused on faults in a real heat source system and evaluate the impact of faults and determine the priority to repair faults in order to develop an appropriate maintenance plan of the system. We developed a detailed simulation model of the system combining automatic control system based on the specifications. Using this simulation, we calculated the system behavior without faults and behaviors with thirty-five faults. We evaluated the yearly impact of the faults using the system coefficient of performance (SCOP) and the peak power as indicators. In addition, using the actual FDD results in previous studies, we also evaluated faults in consideration of the actual daily impacts of them. We found that there were differences in the priority depending on the indicators. we expected that this fault evaluation method helps an operation and maintenance of the system.