This applies for any media filter. VFD drive on the motor can keep airflow constant and increase energy usage instead, but for most fans the increase in static

This applies for any media filter. VFD drive on the motor can keep airflow constant and increase energy usage instead, but for most fans the increase in static pressure means less air volume. Heavily loaded filters can also have more air bypassing the filter, which may or may not be significant depending on the application. For this kind of air filter bypass just subtracts from the airflow through the filter media.