Radiant barriers are materials that are installed in homes or buildings to reduce summer heat gain and winter heat loss, and as a result reduce heating and cooling energy usage and its cost. All materials give off, or emit, energy by thermal radiation as a result of their temperature. The amount of energy emitted depends on the surface temperature and a property called "emissivity". The emissivity is a number between zero (0) and one (1), the higher the emissivity, the greater the emitted radiation.
The benefit of attic radiant barriers is primarily in reducing air-conditioning cooling loads in warm or hot climates. Radiant barriers usually consist of a thin sheet or coating of a highly reflective material, usually aluminum, applied to one or both sides of a number of substrate materials. These substrates include Kraft paper, plastic films, cardboard, plywood sheathing, and air infiltration barrier material. Some products are fiber reinforced to increase the durability and ease of handling.
A radiant barrier reduces heat transfer in the air space between the roof deck and attic floor, where your conventional insulation is usually placed. A radiant barrier helps keep your home cool in the summer and warm during the winter; and thereby reducing your energy costs.