Fault Detection and Simulation for Large Building HVAC Systems

The primary purpose of this paper is to evaluate the energy impacts of faults in building heating, ventilation, and air conditioning systems and determine which systems’ faults have the highest effect on the energy consumption. With the knowledge obtained through the results described in this paper, building engineers and technicians will be more able to implement a data-driven solution to building fault detection and diagnostics

In the United States alone, commercial buildings consume 18% of the country’s energy. Due to this high percentage of energy consumption, many efforts are being made to make buildings more energy efficient. Heating, ventilation, and air conditioning (HVAC) systems are made to provide acceptable air quality and thermal comfort to building occupants. In large buildings, a demand-controlled HVAC system is used to save energy by dynamically adjusting the ventilation of the building. These systems rely on a multitude of sensors, actuators, dampers, and valves in order to keep the building ventilation efficient. Using a fault analysis framework developed by the University of Alabama and the National Renewable Energy Laboratory, building fault modes were simulated in the EnergyPlus whole building energy simulation program. The model and framework are based on the Department of Energy’s Commercial Prototype Building – Medium Office variant. A total of 3,002 simulations were performed in the Atlanta climate zone, with 129 fault cases and 41 fault types. These simulations serve two purposes: to validate the previously developed fault simulation framework, and to analyze how each fault mode affects the building over the simulation period.

The results demonstrate the effects of faults on HVAC systems, and validate the scalability of the framework. The most critical fault cases for the Medium Office building are those that affect the water systems of the building, as they cause the most harm to overall energy costs and occupant comfort.