It appears that EP models of UFAD systems control zone conditioning in a manner very similar to a VAV system; when a zone is in need of conditioning, airflow is increased to that zone at a fixed supply air temperature. AirTerminal:SingleDuct:VAV:Reheat:VariableSpeedFan objects are used as zone air terminal objects. The distinguishing feature of UFAD models in EP seems to be the use of the RoomAirSettings:UnderFloorAirDistributionInterior/Exterior objects to model the stratification effect of UFAD.
In practice, "proper" UFAD system control is to modulate the supply air temperature based on zone demands and keep air flow/plenum pressure constant, at least for a single large interior zone with similar internal gains and served by a single AHU. Is there way to do this in EP, or other program, without using something like a custom solution based on a supply air temperature reset via SetpointManger objects?