EnergyPlus will typically operate the fan to meet the load the system sees (either ventilation, heating, or cooling).

Since your DOAS operates only to meet the ventilation requirement, you You can set the ventilation requirements using the DesignSpecification:OutdoorAir object's Outdoor Air Flow Rate Fraction Schedule Name field.

You can also The only way to override this behavior and set the flow rate of the fan directly using is through an EMS Actuator on the "Fan Air Mass Flow Rate".

EnergyPlus will typically operate the fan to meet the load the system sees (either ventilation, heating, or cooling).

You can set the ventilation requirements using the DesignSpecification:OutdoorAir object's Outdoor Air Flow Rate Fraction Schedule Name field.

The only way to override this behavior and set the flow rate of the fan directly manually is through an EMS Actuator on the "Fan Air Mass Flow Rate".