Peak temperatures were only 2-5 degrees higher than the temperature of shingles under the same conditions without a radiant barrier. Without a radiant barrier, your roof radiates solar-generated heat to the insulation below which absorbs the heat and gradually transfers it to the ceiling and the interior of the home. This heat transfer makes your air conditioner run longer and consume more electricity. A cooler attic also transfers less heat into air conditioner ducts. Radiant barriers can expand the use of space in your home such as garages, workrooms, porches, etc.
New construction is the ideal time for installation but radiant barriers also can be retrofitted.
What the experts say about Radiant Barriers . . . . . . . . A radiant barrier can greatly improve your comfort level, especially in second-floor bedrooms. During mildly hot weather, attic radiant barriers can reduce the heat enough that you may not need to operate your air conditioner at all.