An air filter pressure loss model for fan energy calculation in air handling units

Air filters consume a significant part of the fan power in air handling systems. Due to lack of suitable models, the fan energy associated with the filter pressure drop is often estimated based on average airflow and average pressure drop across the filter. Since the pressure drop varies nonlinearly with airflow and the filter resistance varies with dirt build-up, current methods often produce erroneous results. This paper presents a new air filter pressure loss model that has been developed and verified using experimental data. The model projects the pressure losses across the filter for both constant and variable airflows. The inputs to the model are the airflow rate, the time of use, the initial design and final pressure losses at the design flow rate, and the coefficient of a power law regression of pressure loss as a function of airflow rate. The air filter pressure loss model may be implemented in hourly building energy simulation programs that perform hourly simulation at the air handling unit level. Copyright (C) 2003 John Wiley Sons, Ltd.