In regard to thermal reflective insulation material with aluminum foil on both sides and polyethylene air bubble enclosed between the two layers of aluminum foils – what is the role of the air bubble and how does it contribute by reducing the heat transfer by radiation?
Answer:
The air bubble only contributes a small amount of resistance to heat flow by CONDUCTION. It has no effect on the radiant transfer. The other function of the bubble material is as a medium for holding the reflective surface(s) in place and providing a structure for easy installation.