Mechanically ventilated spaces and naturally ventilated spaces

As baseline model I have to model System 6 according to Table G3.1.1A. On a floor the spaces that have windows are naturally ventilated while the internal spaces are mechanically ventilated. G3.1.1 states that "For system 5, 6, 7, and 8 each floor shall be modeled with a separate HVAC system". I think that modeling only one AHU for the whole floor would be inappropriate, because in the baseline model outdoor air would be provided through the mechanical system to the whole floor (while in the proposed model only some spaces are mechanically ventilated). For this reason in that floor I would model two AHUs: one doesn't supply outdoor air and is connected only with spaces that are naturally ventilated. Would it an acceptable solution?