Influence of occupant behavior on the energy performance of variable refrigerant flow systems for office buildings: A case study

Currently, the controversies on the energy saving potential of Variable refrigerant flow (VRF) systems compared with other heating, ventilation, and air conditioning (HVAC) systems for office buildings still exist. In this study, a VRF system for an office building is investigated in field. The actual occupant behavior (OB) was presented statistically and imported to the energy model of VRF systems developed by the authors to compare the energy performance of VRF systems, with and without considering OB. The statistical results indicate the diversity in the on-duration periods and on-off times of each indoor unit (IU) is highly significant. According to the simulated results, the energy consumption of the VRF system under a continuous operation scheme is approximately 1.8 times that of the actual operation scheme owing to the OB. The total energy consumption of IUs with high air volume setting could be more than three times that of the actual operation scheme with a low air volume setting. In addition, the energy consumption intensity of the VRF system was presented by the parametric analysis on the different occupant thermostat setting temperature. Therefore, the OB contributes significantly to the energy performance of VRF systems, which should be considered for comparison with other HVAC systems.