Most commonly, what is called a Radiant Barrier Roof is a roof which has had modifications to its underside to control the flow of heat. During the summer, the radiant barrier roof keeps the heat from the sun from heating the attic and thus the house or structure under the attic. And, during the winter the heat from your furnace is partially controlled from loss to the outside.
Heat always moves to cold. By placing the radiant barrier roof in the path of the flow of heat, the heat flow can be reduced, by a variable amount depending on the type of radiant barrier product used.
There are numerous products that can be used to produce a radiant barrier roof. One example is aluminum foil types of sheeting that can be applied to the rafter bottoms. Care must be used to place this foil in the correct position. If the foil is sandwiched between two other solids (decking, foil, rafter) or (decking, foil, shingles) the radiant barrier roofing will fail. It will act as a conductor! Other products that can be described as a radiant barrier roof modifier include solid ceramic particles, aluminum powders and flakes and hollow glass bubbles that can all be mixed with paint and applied to the underside of the roofing deck and rafters.
Typically, a radiant barrier roof is thought to protect a structure during the summer by preventing the full radiant heat of the sun from entering. But it can also help during the winter by keeping some of the radiant heat from your furnace from leaving through the attic. For people who live in colder climes, an application of a paintable radiant barrier placed on the ceilings and interior perimeter walls will control furnace heat loss much better than the radiant barrier roof.
With a combination of applications; radiant barrier roof, radiant barrier coatings on interior and exterior walls and on interior ceilings, you can provide your structure with an excellent way to prevent unwanted heat loss, lower your energy bills and keep your structure much more comfortable.