Radiant Barrier Insulation Explained

How Radiant Heat Works

• Radiant heat travels in a straight line, heating solid objects in its path. When the sun's energy hits the roof, heat is absorbed by the roofing material. It then radiates to cooler surfaces within the attic, warming the interior of the attic and air ducts. In the winter, the heat from your furnace radiates through the walls and roof causing heat loss in the home.

How Radiant Barrier Insulation Works

• Radiant barrier insulation consists of a layer of insulation backed with foil. Insulation is installed between rafters or wall joists with the reflective surface facing the interior of the attic or living space. Heat entering from the outside during the summer is reflected away from the home, while during the winter, heat from inside the home is reflected back to the living area.

Effectiveness

• Performance of the radiant barrier insulation depends on its emissivity -- a measure of the amount of heat that leaves the barrier --, reflectivity -- how much radiant heat it reflects --, and the angle at which the radiant heat strikes the insulation. The most effective barrier has an emissivity number of 0.1 or less, with a reflectivity score of 95 to 97 percent, and is installed so that radiant heat strikes the barrier at a 90 degree angle.

Energy Savings

• In warm climates, radiant barrier insulation may reduce cooling costs 5 to 10 percent. In colder climates, where heat loss becomes a major issue in winter, radiant barriers reflect the heat back into the room reducing heating costs. Energy savings depend on the size and style of your home, weather conditions, the "tightness" of your home, efficiency of your heating system and the amount of insulation.