Quantification of the Energy Saving Associated With Early Detection of Faulty Operation of Rooftop Units

Abstract

Abstract As stated in the U.S. Energy Information Administration’s 2018 survey, commercial building space heating, ventilation, and air-conditioning (HVAC) operation, accounted for little more than one-half of total end-use consumption in the U.S., or approximately 3,529.24 trillion Btu. This HVAC industry contains multiple subsections and different equipment, but one of the most used equipment types with a significant market share in the commercial industry is the packaged rooftop unit (RTU). When units operate with faults, malfunctioning sensors, actuators, or airflow issues, the system will experience longer run-time to achieve and maintain conditions, thus increasing energy use and cost. Therefore, reducing energy consumption via early recognition of faults and taking prompt corrective actions will contribute to the system’s overall energy saving. The authors of this paper will present uncertainty-based simulated (computer-based) model of multiple RTUs with selected capacities to quantify the effects of different sensor and actuators malfunctions on the overall system’s operation while evaluating the system’s energy impact under varying fault conditions. Room temperature, outdoor air temperature, and cooling coil leaving air temperature sensors are among the primary sensors the RTU’s control panel will utilize to facilitate the planned system evaluation and are analyzed in this research. The positions of the outdoor air and return air dampers are also evaluated for their respective impact on energy use. With this, the authors demonstrate the potential excess energy consumption of operating a typical RTU with faults and the potential energy savings opportunity that can be realized if units operate within the given specifications, and without faults. A novel method for detection of these malfunctions is discussed.