Mixed Mode Ventilation

Dear all, We've got a Hotel building that is designed acc. to local Standards (not ASHRAE 62.1). The guest rooms are mechanically ventilated and have also operable Windows. The Problem is, that neither the OA rate is enough to fulfill the requirments of ASHRAE 62.1, nor the Windows are large enough (smaller than 4% of the floor area). The Ventilation System design Intention is to provide a base IAQ through the mechanical ventiation with the Option for the guests to open the Windows additionaly. I am unsure how to show compliance in this case. My first thought would be to separate the room into 1 the part near the window and Label it as naturally ventilated an 2 the part away from the window and Label it as mechanically ventilated. Has anybody experience with this? What are your general thoughts? Do you think I can avoid an official request to the GBCI? Thank you,Johannes