http://www.AtticFoil.com - Short Summary of How Radiant Barrier Foil Insulation Works In An Attic. Radiant barrier works by reflecting heat coming off the roof. Normally the heat travels across the attic by radiation and is absorbed by the attic insulation. Normal attic insulation only helps to reduce conductive heat (R-Value) flow. Eventually the insulation heats up and the heat is transferred into the home. A radiant barrier will REFLECT the heat coming off the roof and make the INSULATION COOLER. By reducing the insulation temperature, it reduces heat flow into the home. This video addresses the concept of radiant barrier, how to staple it up, partial verses full coverage and attic ventilation.