Energy-saving Effect of VAV・VWV・CO₂ Concentration Control of Air Conditioning System Considering Automatic Control Logic and Parameters

<p>A heating ventilating air conditioning (HVAC) system comprising a heat source unit, an air conditioner, and a water / air transport system accounts for approximately 40% of the energy consumption of a building, so highly efficient design and operation is important. There are many energy-saving methods for air-conditioning systems related to automatic control, but few studies have quantitatively evaluated their energy-saving effects. At the design stage of HVAC system, the equipment is selected according to the load, but detailed automatic control logic and control parameters are rarely examined. Therefore, the control state deteriorates during operation, and the expected energy-saving effect cannot be obtained. To properly evaluate the energy-saving effect at the design stage, programs that can handle various controls are required. the major programs in Japan and overseas are built for the purpose of calculating annual energy consumption. Thus, the actual control was not sufficiently reflected. Therefore, in this study, we constructed a unique program that can quantitatively calculate the energy-saving effect of various controls by reproducing the behavior of the device according to the control logic and control parameters in detail. Further, we examined the energy-saving effect of variable air volume (VAV)・variable water volume (VWV) and CO₂ concentration control. In this study, the VAV / VWV control logic introduced in the experimental building was modeled as faithfully as possible for the existing experimental building. In addition, to quantify the influence of the control state of the equipment, the simulation was constructed by incorporating the physical model and the equipment model in as much detail as possible. Then, to validate the constructed simulation, we confirmed the room temperature calculation model and compared it with the measured values regarding the behavior of the room temperature during the operation of the HVAC system. Through the constructed simulation, VAV/VWV control, constant air volume (CAV)/VWV control, and VAV/ constant water volume (CWV) control were defined as comparison targets, and the annual power consumption was calculated. By comparing the results, the energy-saving effect of the VAV / VWV control was quantified. From the analysis of the control state, the superiority of the VAV / VWV control over CAV or CWV control was confirmed. In addition, the detailed calculation results of each month by the VAV / VWV control showed that the controllability deteriorated at other times when the parameters were adjusted according to the time when the load was heavy. Thus, readjusting the parameters may improve controllability. In the future, by using this simulation, the behavior of each device according to the control can be calculated in detail; therefore, it is expected to be used as an energy-saving design tool at the time of design, parameter adjustment at the operation stage, and defect detection / diagnosis. In the next report, we considered the energy-saving effect and the effect on room temperature controllability when the parameters of the control logic for VAV / VWV / CO₂ concentration control were changed. </p>