How Reflective Insulation works:
Heat is transferred by three methods: convection, conduction and radiation. Enclosed air spaces within a building assembly have resistance to heat transfer and have R-values (per ASHRAE Fundamentals Handbook). Mass insulating materials such as fiberglass, cellulose, cotton or foam enclose small air or gas molecules — their primary function is to reduce convection within the product. Multi-layer reflective insulation uses layers of materials including paper, aluminum foil, and metalized aluminum substrates to enclose air spaces to reduce convection. The low emittance of reflective layers of reflective insulation offer the distinct advantage of significantly reducing radiant heat transfer.