Eco Sun Systems LLC

Energy Savings with Radiant Heat Barriers

All the Radiant Barrier configurations yielded sizable percent savings (17 percent, based on ENERGY STAR Evaluation) and statistically significant reductions in summer attic heat transfer compared to the non-RB case. Also, as the ambient temperature increases, the savings also increase.

The RB on top was the best summer performer. It consistently showed heat flux reductions compared to the non-RB case of about 40 percent for almost all ambient temperatures and even showed savings (17 percent) during mild temperature and night summer conditions.

The RB configurations provide statistically significant reductions in winter attic heat fluxes in many, but not all, situations. The percent savings during night hours and during below 35° conditions, when heating loads are the highest, are usually sizable (from 6 to 23 percent) and the differences between the RB configurations and the non-RB case are often statistically significant during these conditions.

(Sources: Tennessee Valley Authority - Chattanooga, TN)

The Radiant Barrier works by reflecting the radiant heat created by the sun. The radiant heat is reflected by the Radiant Barrier and back out of the attic. Some of the radiant heat causes the temperature above the Radiant Barrier to increase rising to the top of the attic. This heat then escapes through the attic vents or gable vents. An addition of a powered attic fan allows for more of the heat to be vented out of the attic keeping the attic below the radiant barrier at a relatively cool temperature. Installing the radiant barrier under the rafters is the recommended installation in hot climates. It involves stapling the radiant barrier to the underside of the rafters, creating a false roof inside the attic. The radiant barrier blocks the radiant heat from reaching your HVAC unit(s), duct work, and underlying attic insulation keeping energy costs down and improving the comfort of your home. Installing the radiant barrier on the top of the insulation on the attic floor is recommended in moderate climates. Installing the radiant barrier on the top of the insulation on the attic floor in the summer keeps the radiant heat from reaching the insulation and entering into the living space of the house. This method does not prevent the radiating heat to reach the HVAC unit(s) and ducting. However, in the winter months the radiant heat of the house is reflected back into the living space, reducing the amount of heat lost into the attic.