Baseline HVAC schedules

The project will apply for certification under LEED v2009 NC. The Proposed design is a 50,000 sf three story building (two above ground plus a full basement) with a central atrium. It includes a large cafeteria and some office space. The cafeteria is largely open due to a central atrium and open passage ways in to the kitchen and back-of-house support areas. The HVAC system consists of four large identical DOAS air-handlers that deliver conditioned air to the kitchen, serveries, and dining areas. There are some heat pumps to serve loads at the peripheral zones that do not provide outside air. During occupied hours, when the kitchen and servery exhaust systems are running, the four air-handlers provide outside air to all of the dining areas as well as the serveries and the kitchen with large amounts being transfer air from the dining areas to the serveries to provide replacement air for the exhaust hoods. The mechanical design calls for two of the four DOAS air-handlers to run at 50% speed during unoccupied hours to provide building pressurization and heating or cooling of the delivered air. This would be the equivalent of all four running at 25% speed, delivering one-quarter of the occupied outside air amount. The Baseline qualifies for System 5, VAV with Reheat, one system per floor. The kitchen and serveries on the ground level floor qualify for G3.1.1 Exception b due the high loads in the kitchen and serveries, so System 3, PSZ-AC is used for these zones. The kitchen and servery exhaust is turned off during unoccupied periods, so the PSZ-AC units could be off as well, but cycle at night. My question is how to assign availability schedules to the baseline HVAC systems when essentially there is no transfer air. The three VAV with Reheat AHUs would be the appropriate units to run overnight to provide comparable building ventilation overnight. Should all three run at 25% speed overnight? Should the PSZ-AC systems for the kitchen and serveries run at 25% speed overnight (not sure this could be modeled)? Thanks in advance for ideas and guidance!