Energy saving potential of centralized heat pump-based airconditioning system for an office building
This study explores a hybrid air-conditioning configuration for office buildings in which a centralized airsource heat pump (ASHP) supplies moderately conditioned water to multiple distributed water-to-air terminal heat pumps. The system is intended to mitigate the significant performance fluctuations commonly observed in decentralized air-to-air ASHP units when exposed to varying outdoor temperatures. To examine the potential benefits, a detailed thermodynamic cycle evaluation and annual performance simulations were performed using TRNSYS 18 and Engineering Equation Solver (EES). A representative office building model was adopted to quantify heating and cooling demands under realistic operating conditions. The simulation results demonstrate that the proposed system achieves noticeably higher compressor isentropic efficiencies compared with both standalone and fully centralized reference configurations. Individual terminal units in the hybrid system reached an average isentropic efficiency of approximately 0.66, while the central unit achieved around 0.80 due to the reduced compression ratio resulting from stabilized heat-source temperatures. Correspondingly, the total annual energy consumption of the proposed configuration was calculated to be about 99.4 MWh, a 16% and a 1.18% reduction relative to a conventional central ASHP system and a conventional individual ASHP system, respectively, when the energy use of the central heat pump and circulation pumps is included. These findings indicate that supplying a moderated water-based heat source to individual units can substantially enhance system stability, reduce compressor work, and yield significant annual energy savings.