When the sun heats a roof, it’s primarily the sun’s radiant energy that makes the roof hot. Much of this heat travels by conduction through the roofing materials to the attic side of the roof.
The hot roof material then radiates its gained heat energy onto the cooler attic surfaces, including the air ducts and the attic floor.
A radiant barrier reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic.
Radiant barrier can reflect up to 97% of solar radiation which translates into an attic heat reduction of up to 30°F. A cooler attic space means less heat moving to the cooler space below the attic. The hotter it gets the better radiant barriers work. The reduced attic temperature increases the efficiency of attic duct work which prolongs the life of your heating and cooling systems because there are fewer cycle times.
Radiant barrier helps to improve comfort in the building interior during the warm summer months and reduces energy costs. Because heat always moves from hot areas to cold areas, radiant barrier sheathing also prevents heat transfer from the warm interior during the cooler winter months.