Improving Simulation Accuracy of VRF Heat Pump Systems through Manufacturer-Informed Performance Modeling
Accurate modeling of cooling and heating systems is fundamental to reliable building energy simulation, particularly for high-performance buildings targeting low-carbon objectives. Variable Refrigerant Flow (VRF) heat pump systems are widely adopted due to their flexibility and efficiency; however, simulation accuracy strongly depends on the quality of performance input parameters. This study investigates how different performance curve inputs influence the predictive reliability of VRF system simulations in EnergyPlus.
Testbed Validation and Model Calibration
A validated experimental testbed model, calibrated using field measurements from a controlled test facility in South Korea, was employed to ensure realistic baseline performance. The calibrated model provided a reliable reference for comparing simulation outputs under varying input curve assumptions, enabling quantitative assessment of modeling accuracy.
Comparison of Performance Input Configurations
Three simulation configurations were evaluated: Case 1 using default EnergyPlus VRF performance curves; Case 2 combining default curves with manufacturer-rated coefficient of performance (COP); and Case 3 implementing manufacturer-derived performance curves alongside rated COP values. This structured comparison isolates the influence of curve accuracy and rated efficiency inputs on overall simulation outcomes.
Quantitative Error Analysis and Model Accuracy
Results reveal substantial differences in predictive accuracy among the cases. Case 1 exhibits significant deviation from measured data, with a CV(RMSE) of 59%, indicating limited reliability of default performance curves. Incorporating manufacturer-rated COP in Case 2 reduces error significantly to 13%. Case 3 achieves the highest accuracy, reducing CV(RMSE) further to 9%, demonstrating strong agreement with real operational data.
Temperature- and Load-Sensitive Behavior Representation
Simulations using manufacturer-derived curves more effectively capture the VRF system’s temperature-dependent and load-sensitive performance characteristics. This enhanced representation improves the model’s ability to reflect real-world operational dynamics, particularly under variable climate and part-load conditions typical of high-efficiency building operation.
Implications for Energy Modeling and HVAC Design
The novelty of this study lies in the development and validation of a manufacturer-informed curve-fitting methodology that quantitatively improves VRF modeling accuracy in EnergyPlus, reducing simulation error from 59% to 9%. The findings emphasize the critical importance of integrating real-world performance data into simulation workflows. This approach provides a practical framework for improving reliability in building energy assessments and supports more accurate, performance-oriented HVAC system design for low-carbon buildings.
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