You assumptions are incorrect. "Kool Ply" is a product which consists of standard plywood decking with a foil backing. The foil side is placed towards the attic. The RBS is not a substitute for adequate ventilation. This RBS reflects back infared radiation back to the plywood that would normally be transmitted to the attic. The principle is simple. Forest firefighters utilize this physic principle because they carry with them a foil blanket to reflect the infared radiation away from them as the are laying on the ground surrounded by fire that is overtaking them. At the local lumber yard they have a "Kool Ply" display. An A-frame made with 1/2 standard plywood and the other half with "Kool Ply". A very hot light blub is at the center. The bulb emmits infared radiation. The air at the top is divided off. The temp of the air above the plywood is 25 to 30 hotter than the "Kool Ply side. All this due to a radiant barrier reflecting the IR back towards the blub.