How does Radiant Barrier (RB) work?

Radiant Barrier is unlike mass insulation which only slows down or resists heat transfer. RB reflects heat. Heat always goes cold by natural law – the problem is how to keep the heat in in the winter and how to keep it out in the summer. There are three ways in which heat goes from warm spaces to cold spaces: CONDUCTION is direct heat flow through a solid object such as a wall or a ceiling. CONVECTION is heat movement through air, occurring when air is warmed. The warm air expands, becoming less dense and rising. RADIATION is the movement of heat rays across air spaces from one warm object to a cooler object. The heat we feel from a wood stove or a quartz space heater is radiant heat. ALL OBJECTS AND BODIES GIVE OFF RADIANT HEAT. Even the insulation in your attic gives off radiant heat to the cold attic space in the winter, and to the living space in the summer. Regular insulation won’t stop radiant heat loss. Radiant heat must be REFLECTED with a radiant barrier.

What is the 'R' Value of Radiant Barrier?

The “R” value depends on the number and size of the airspaces surrounding the RB and on the direction of the heat flow. Since RB is usually installed on top of existing mass insulation, its R-value is a moot point. It is RB’s ability to reflect heat that makes it such an energy saver.

How does RB keep me warmer in the winter?

Just like wrapping a baked potato in aluminum foil keeps a potato warm longer by holding the heat in, covering your attic rafters with RB holds heat in the house. Another analogy would be that RB in the winter works just like a space blanket, which, although very thin and lightweight, holds your body heat in. A thin space blanket can keep you warmer than several heavy blankets.

OKAY, RB keeps heat in in the winter, but how can it keep heat out in the summer?

Just like a space suit, RB reflects the sun’s heat before it can warm up the insulation in your attic. When the insulation stays cooler, your house will stay cooler. It helps to understand how RB will work for you if you think of other things that work in much the same way. ASTRONAUTS’ SPACE SUITS – keep body heat and reflect the sun’s heat away. THERMOS BOTTLES – keep hot things hot and cold things cold. They are almost perfect insulators. The tight seal and air space prohibit heat transfer by conduction and convection. The reflective surfaces inhibit radiation heat transfer. If the bottle starts out hot, it stays hot because very little heat is transferred to the cooler outside. If it starts out cold, it stays cold because very little heat is transferred from the warmer outside.

Will Energy Attic Radiant Barrier affect my cell phone use?

NO the RB will NOT affect your cell phone use at all

What if RB collects dust over a period of time? Will it still work?

This very issue has been studied by research institutes. Most attics don’t accumulate enough dust to affect RB’s ability to save energy costs. Thousands of homes and structures have had RB installed for as long as ten years or more with no significant accumulation. Energy Attic installs the RB permanently, and it will never come loose or fall down.

Won't my roof get hotter when I have radiant barrier in my attic?

No. Radiant barrier has been used extensively in the south, and field tests confirm there is no difference in roof temperatures.

Where do you install radiant barrier?

The preferred method is stapling it under your rafters or crawl space. Our professional installation on the rafters maximizes airflow into your attic to utilize the radiant barrier properties.

What about foil-faced fiberglass? Isn't it just as good as RB?

No. The foil on the fiberglass is in direct contact with the attic floor. Aluminum foil becomes more conductive when in contact with a solid surface. The air space facing the foil surface is of primary importance.

I already have plenty of insulation in my attic. Do I really need RB?

Regardless of how much insulation you have in your attic, adding RB will save on your heating and cooling expense, and keep you much more comfortable. Energy savings for heating and cooling can vary from 17% to 25% depending on a number of factors, including climate, building configuration, materials used, site, family size and lifestyle. Your RB dealer has been trained to evaluate your home or business and advise you of your savings potential.

Has RB been tested by a qualified independent laboratory or government agency?

The Florida Solar Energy Center at Cape Canaveral has tested radiant barriers in both small scale laboratory and full scale building models. Their results indicate that radiant barriers provide significant resistance to heat transfer. Current tests conducted by the Tennessee Valley Authority and the University of Mississippi support the findings of the Florida Solar Energy Center. Northeastern Illinois University conducted winter tests in residential and commercial structures using infra-red thermograph photography. The photos showed significant resistance to heat transfer over the regular insulation.

Will dust collecting on the top of the product hurt its effectiveness over a period of time?

A1 – Aluminum foil exposed in a vertical position since 1929 to the dust and fumes in the Heat Measurements Laboratory, M.I.T. Samples of this foil have been removed from time to time and the emissivity determined. Over a period of 10 years no appreciable change in emissivity was found.

American Society of Heating and Air Conditioning Engineers’ Journal Section, Jan. 1940, Professor Wilkes, M.I.T.

A2 – Thin layers of dust readily visible to the eye do not cause very serious lowering in the reflective power. The appearance of the surface is not a reliable guide as to its reflectivity for radiant heat, and foil which appears dark or discolored may have lost little in insulating value if the surface film is thin.

The National Bureau of Standards, U.S. Dept. of Commerce, Letter Circular – 535

Will the aluminum corrode and lose its effectiveness?

A1 – Hundreds of samples of aluminum foil have been stored in the laboratory for various periods of time up to 10 years with no visible signs of deterioration.

American Society of Heating & Air Conditioning Engineers’ Journal Section

A2 – Aluminum is highly resistant to the effect of corrosion. Aluminum is constantly being used where it is exposed to weather, salt spray and other conditions, which would adversely affect most metals.

The United States Rubber Co. Booklet, Serving You Through Science, Page 5

Do I need a radiant barrier if my home is already well insulated?

A1  SUMMER – A radiant barrier system can stop 97 percent of the thermal radiation across an attic space. If it is not stopped, that radiant energy would be absorbed by the ceiling insulation and eventually be transferred to the living space below.

The Solar Collector, Quarterly Newsletter of the Florida Solar Energy Center

The heat storage capacity of reflective insulation is low. As a result, it does not store heat during summer days, only to pass it on down into the rooms of the house from the attic at night when coolness is most apt to be desired from the point of view of sleeping comfort.

Progressive Architecture, Nov. 1949, Page 76

A2  WINTER – Reflective foil retrofitted to fiberglass insulated buildings is demonstrably effective in reducing heat loss. Installation of foil in uninsulated buildings would show even more pronounced reduction in heat loss.

Effects Of Reflective Foil On Heat Loss in Attic Floors and Metal Building Installations, Northeastern Illinois University, Prof. Charles Shabica, May 20, 1986

Is radiant barrier effective in the winter?

Yes. It will reduce your heat loss significantly in your home. Energy Attic radiant barrier has year round benefits.

Is Energy Attic Radiant Barrier a Green Product?

Yes. It conserves energy and helps the environment. It is non-carcinogenic, does not emit gases, is very environmentally friendly, and is an Energy Star product, which means it meets strict energy efficiency guidelines set by the Environmental Protection Agency and U.S. Department of Energy.

Why should I use an aluminum radiant barrier instead of paint?

Energy Attic Radiant Barrier is 97% reflective. Based on the Department of Energy standards, a product must have a reflectance of at least 90% to be classified as a radiant barrier. Paint products can range from 10% to 75% reflectance, lab tested not field tested, depending on products and installation technique and must be reapplied in time.

What other products or services do you offer?

Blown-in Johns Manville Climate Pro insulation, thermographic imaging, solar powered attic vents, air conditioning units and duct sealing, radiant barrier duct wrapping.

If we have failed to answer your question, please contact us so that we can add your question to this page.

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