A ventilation system includes a cavity, a fluid motive force device, and a motive fluid supply system. The cavity includes different ventilation level requirements for a plurality of modes of operation. The fluid motive force device includes a suction port, an outlet port, and a motive fluid inlet port. The suction port is coupled in flow communication with the cavity to be vented. A flow supply to the motive fluid inlet port determines a ventilation flow through the suction port. The motive fluid supply system is coupled in flow communication with the motive fluid inlet port. An operation of the motive fluid supply system determines a flow of motive fluid from the motive fluid supply system to the motive fluid inlet port. The flow of motive fluid to the motive fluid inlet port generates a ventilation flow through the suction port approximately matching a current ventilation demand of said cavity.