Naturally Ventilated Underbuilding Parking Garage and 62.1

62.1 has an exahust requirement for mechanically ventilated Parking garages (Table 6-4), with an exception C - no ventilation required if two or more sides comprise walls that are at least 50% open to the outside. But for a naturally ventilated space (5.1), section 6 does not apply, yet 5.1 only requires 4% of occupiable floor area as the minimum opening requirement. This seems like a major difference. ------------------------ My last question is if anyone has modelled a naturally ventilated garage and what information source did you use to apply the most correct air changes to represent the natural ventilation of this space?