I am designing a garage, and trying to achieve natural ventilation. I think I have achieved the required 20% open, as well as 40% perimeter open as per IBC 2006, but what if your garage is really deep? It seems like if you have a very large garage, if you're 150' from the perimeter, air is not likely getting in to the inside of the garage. Is there any requirements, i.e. maximum distance to perimeter opening req'd before needing to implement mechanical ventilation?