Radiant barrier paints are coatings that reflect solar heat from wall surfaces. Radiant barrier coatings are also popular for roofs. These paints and coatings are white or metallized. Radiant barrier paints and roof coatings can produce dramatic savings in air conditioning costs. To generate savings, these paints and coatings must be installed on the building’s exterior to reflect solar energy, thus reducing the building’s cooling requirement. The air conditioning savings are dependent on the amount of area covered by the coating, the reflectivity of the coating, and the direction that the coated roof or wall faces.
Some manufacturers claim that painting the interior with a radiant barrier paint saves energy in the heating season. The problem with installing a radiant barrier on the interior side of an exterior wall is that it takes a metallized surface to reflect low temperature radiant heat. A metallized radiant barrier looks like a mirror and this doesn’t fit most homeowner’s interior decorating tastes. Any radiant barrier coating without a shiny surface won’t reflect low-temperature heat from inside a home. Therefore radiant barrier coatings aren’t useful for reflecting heat back into the home during the heating season.
Radiant barrier paints work well to save air conditioning costs but they aren’t effective at reducing heating costs.