TA-23-C011 – Fan Power Modeling of Commercial HVAC Systems: A Comparative Study

The fan unit in a heating, ventilation and air conditioning (HVAC) system can provide a fast power response and be modeled using the typical fan law or empirical equations. In this study, the HVAC system for a commercial building is modeled with different ways of calculating the fan power. Three typical days standing for hot, cold, and medium days, respectively, were simulated and the fan power calculated by different methods were compared. Simulation results show that the value for fan power calculated by the typical fan law is lower than the actual fan power while the power estimated by empirical equations is very close to the actual power. It has also been found that the fan power profile calculated by the typical fan law has fairly strong correlation with the actual fan power profile. A coefficient is proposed to be added in the typical fan law equation to match the daily fan electricity usage with the actual value.