Frequently Asked Questions

Smart Foils Frequently Asked Questions

Tests by The Florida Solar Energy Center, The Tennessee Valley Authority and The University of Nevada at Las Vegas, along with many other groups, have shown that radiant barrier systems work effectively. “SMARTFOILS” “Home Barrier” and “Business Barrier” radiant barrier products are a proven low cost method of lowering your cooling and heating energy costs.

Questions & Answers:

Q: What is a radiant barrier?
A radiant barrier is a layer of aluminum foil placed in an attic or wall airspace to block radiant heat transfer between a heat-radiating surface (such as a hot roof) and a heat-absorbing surface (such as conventional attic insulation). Figure 1 illustrates the locations in which a radiant barrier may be installed in an attic. Only locations 1 and 2 are recommended for sheet radiant barriers because dust accumulates on the radiant barrier if it is installed at location 3.

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Q: What are the benefits of radiant barriers in attics?
In hot and cold climates, the benefits of “SMARTFOILS” radiant barriers include both dollar savings and increased comfort. Without a radiant barrier, your roof radiates solar-generated heat to the materials below it. The roof trusses absorb the heat, and they gradually transfer the heat to the insulation and the material that it touches, the ceiling. This heat transfer makes your air-conditioner run longer and consume more electricity. In the summer, when your roof gets very hot, a radiant barrier cuts air-conditioning costs by blocking a sizable portion of the downward heat gain into the building. A cooler attic transfers less heat into the air conditioning ducts, so the cooling system operates more efficiently. A “SMARTFOILS” radiant barrier blocks 97% of the heat radiated down by the roof, so that it can’t reach the duct work or the insulation.

In the warm spring and fall, radiant barriers may save even more energy and cooling dollars by increasing your personal comfort. During these milder seasons, outdoor air temperatures are comfortable most of the time. Yet solar energy still heats up your roof, insulation, attic air and ceiling to temperatures that can make you uncomfortably warm. An attic radiant barrier stops almost all of this downward heat transfer so that you can stay comfortable without operating your air-conditioning during mild weather.

You may also find that radiant barriers can expand the use of space in your home. For example, un-insulated, unheated and non air-conditioned spaces such as garages, porches and workrooms can be more comfortable with radiant barriers. And because radiant barriers keep attics cooler, the attic space is more usable for storage.

In the wintertime, “SMARTFOILS” radiant barrier systems keep as much as 93% of the heat in your home or business from escaping through the place most likely to lose the heat-the roof! Remember one of the most basic principles of physics, heat rises. “SMARTFOILS” radiant barrier systems act to keep reflecting the heat in your home or business back into the interior of the structure. You may not be able to keep your employees or children from leaving the doors and windows open in the dead of winter, but at least your roof won’t be “draining” your bank account. Stop paying to “heat the outside!”
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Q: How do radiant barriers “block” heat transfer?
Aluminum foil (the operative material in radiant barrier systems) reflects thermal radiation very well. It also emits (gives off) very little heat. In other words, aluminum is a good heat reflector and a bad heat radiator.

Your mother and grandmother probably made use of these same physical properties through simple “kitchen physics.” They covered the Thanksgiving turkey with a loose “tent” of aluminum foil before they put it into the oven. The foil helped to reflect the oven’s thermal radiation, so that the meat cooked as evenly on top as it did on the bottom. They then removed the foil briefly to let the skin brown, but when they took the bird from the oven, they “tented” it with foil again. Since aluminum doesn’t emit much heat, the turkey stayed hot while the rest of the meal was being prepared.

The same principles of physics that apply to cooking a turkey also apply to a “SMARTFOILS” radiant barrier system. Aluminum foil across the attic airspace reflects heat radiated by the roof. Even if the radiant barrier material has only one aluminum foil side, and that side faces down, it still stops downward heat transfer. This is because the foil will not emit the roof’s heat and allow it to radiate to the insulation below it.

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Q: How much can radiant barriers save?
Since all homes, businesses and lifestyles are different, “SMARTFOILS” cannot precisely calculate your personal savings from a radiant barrier system. It is reasonable, however, to expect that a “SMARTFOILS” radiant barrier system can save from 8-14 percent off of your annual cooling costs. During the months when your heating system is in operation, you should be able to realize savings from 12-26 percent on heating costs.

During warmer months, your savings from a “SMARTFOILS” radiant barrier system will depend on the amount of heat the roof and attic contribute to your home’s cooling load. “Cooling load” is the total amount of heat that your air-conditioning system must remove in order to maintain comfortable indoor air temperatures. In general, the more energy efficient the rest of your home is, the larger the percentage of energy you save from a “SMARTFOILS” radiant barrier system, due to the fact that the roof and attic make up a larger portion of the cooling load.

Figure 2 shows a breakdown of cooling loads in a typical 1500-square-foot Central Florida home. The attic (including heat gains to the duct system) accounts for 22 percent of the total cooling load. In this house, an attic radiant barrier could save 8-12 percent on the annual air-conditioning costs.

After a “SMARTFOILS” radiant barrier system has been installed in your home or business, it will also reduce your heating costs. Aluminum is a good heat reflector and a bad heat radiator. It also emits (gives off) very little heat. So, as the heat in your home or business rises, it is reflected back into the interior of the structure since your “SMARTFOILS” radiant barrier system is not emitting (radiating) the heat to the outside.

Your mother and grandmother probably made use of these same physical properties through simple “kitchen physics.” They covered the Thanksgiving turkey with a loose “tent” of aluminum foil before they put it into the oven. The foil helped to reflect the oven’s thermal radiation, so that the meat cooked as evenly on top as it did on the bottom. They removed the foil briefly to let the skin brown, but when they took the bird from the oven, they “tented” it with foil again. Since aluminum doesn’t emit much heat, the turkey stayed hot while the rest of the meal was being prepared. Help to keep your heat inside with a “SMARTFOILS” radiant barrier system!

For maximum heating and cooling efficiency we recommend (for attic radiant barrier systems) that a “two sided aluminum” product be employed.

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Q: Are claims of greater savings true?
As in most cases, claims for radiant barriers that sound too good to be true are too good to be true. For air conditioning in the warmer months, if your roof accounts for less than 20 percent of your cooling load, then an attic radiant barrier can’t possibly save you more than 20 percent on your energy bills.
Claims of greater savings may simply be the results of misunderstanding. For example, the FSEC has measured and reported that radiant barriers can reduce heat gain through R-19 insulated ceilings by over 40%. If the ceiling portion of the total cooling load is 20%, that’s a reduction of 40% of 20%, which amounts to an 8% savings on the total cooling load.

If all the facts and figures tend to confuse you, just remember that a “SMARTFOILS” radiant barrier system can save you approximately 8% to 14% on your air-conditioning costs in the “sunbelt.” Any sunbelt homeowner knows that an 8% to 14% savings on air-conditioning bills is very significant. Remember the “SMARTFOILS” Warranty:

The “SMARTFOILS” Warranty: We offer a limited lifetime warranty with each “SMARTFOILS” “Home Barrier” or “Business Barrier” radiant barrier product. Should any part of the material in your properly installed “Home Barrier” or “Business Barrier” radiant barrier product become defective, the replacement square footage will be replaced at no charge and postage paid. Do not send the entire square footage—only the area in question.

In addition, SMARTFOILS” also offers a “20/20” guarantee providing that if at the end of a five (5) year period (commencing upon the completion of your properly installed—and subsequently properly maintained—“Home Barrier” or “Business Barrier” radiant barrier product) you have not reduced your electrical kilowatt hour consumption (for electrically powered HVAC systems), or your natural gas consumption (for gas powered HVAC systems) by at least 20%, we will return to you 20% of the original purchase price of the product. The purchaser is solely responsible for maintaining and providing to “SMARTFOILS,” upon demand, copies of their electrical bills and or natural gas bills for the one year period prior to the proper installation of their “Home Barrier” or “Business Barrier” radiant barrier product, and for the five (5) year period subsequent to the completion of the proper installation. Because these documents are necessary to accurately assess your energy situation, failure to provide these documents within 30 calendar days of “SMARTFOILS” demand to do so voids this “20/20” guarantee. For either of the aforementioned warranties, “SMARTFOILS” is not responsible for any re-installation costs, or for any consequential damage due to removal or re-installation. SMARTFOILS” “Home Barrier” or “Business Barrier” radiant barrier products are not warranted against improper installation, water damage, or by any acts of God, or by any negligent or intentional acts or omissions on the part of the purchaser or any other individual(s).

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Q: Which material is best?
Each application, both residential and commercial, requires different materials and installation techniques. At “SMARTFOILS,” we suggest that you look for the following characteristics:

Low emissivity (the lower the better)

Appropriate fire rating (as required by building codes)

Ease of material handling

Strength of reinforcement materials

Appropriate material width for installation

All of “SMARTFOILS” “Home Barrier” and “Business Barrier” products are manufactured with only the strongest reinforcement materials, in an extensive range of available widths, all of which are easily handled. Our “Home Barrier” and “Business Barrier” radiant barrier products provide you with the lowest emissivity aluminum commercially available, and we are confidant that we can deliver products to satisfy even the strictest of building codes with regards to fire ratings.

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Q: What does a radiant barrier cost?
Costs for a “SMARTFOILS” radiant barrier system depend on several factors, including the following:

Does the purchase include installation?

How much product (“SMARTFOILS” gives generous volume purchase discounts) is being purchased?

What type of “SMARTFOILS” “Home Barrier” and “Business Barrier” product(s) are needed to complete the job? Different manufacturing methods and type(s) of reinforcement materials can create additional product costs.

In order to properly assess your radiant barrier needs, we invite you to call or email us. Our “SMARTFOILS” customer service representatives are trained to help you get your job done right, utilizing the “Home Barrier” and “Business Barrier” product(s) best suited for your particular application.

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Q: The “SMARTFOILS” product that I’m using has only one foil side; should the foil face the roof?
NO! In attics, single-sided radiant barrier material should be installed with the foil side facing down toward the attic interior. This may run contrary to your intuitive feelings for “how things should work,” but it does work, and work well.

To understand how it works, remember that aluminum foil (the operative material in radiant barrier systems) reflects thermal radiation. It also emits (gives off) very little heat. In other words, aluminum is a good heat reflector and a bad heat radiator. The “bottom line” is that foil reflects radiant energy very well, but does not radiate heat well. It does not emit heat to the cooler surfaces around it.

If you install a single-sided radiant barrier with the foil side facing up, the aluminum will temporarily reflect the thermal energy radiated by the hot roof. If you install a single-sided radiant barrier with the foil side facing down, the aluminum will not radiate the heat it gains from the roof to the cooler insulation it faces.

At first, a single-sided radiant barrier will work equally well with the foil side facing up or down. But over time, dust could accumulate on the surface of the foil facing up. The dust will reduce the radiant barrier effect by allowing the foil to absorb rather than reflect thermal (solar) radiation. A radiant barrier with the foil side facing down will not collect dust on the foil surface, and it will continue to stop the transfer of radiant heat from the hot roof to the insulation below it.

Even if you use a “SMARTFOILS” double-sided radiant barrier product, it works best when installed at the roof or bottom cord of the truss level of the structure, so that the bottom side faces the attic airspace and will not collect dust.

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Q: How should I install my “SMARTFOILS” “Home Barrier” radiant barrier in my attic?

The most effective way to install a radiant barrier in an existing attic is simply to staple the foil material to the underside of the top chord of the roof trusses or to the underside of the roof decking.

It’s not very easy to work in any attic space, even one with a steep roof pitch. Keep in mind that any misstep could be disastrous, since most attic floors are not really floors at all. Most attic floors are just 2x4s holding ceiling drywall underneath, drywall topped by conventional insulation. Remember, safety first! Your first misstep could be very painful, and it will most certainly be messy! It is also strongly recommended that you take care to avoid compressing existing insulation in the attic, as doing so will compromise the effectiveness of the insulation.

Materials and tools needed to completely install a radiant barrier system include the following:

Enough “pre-cut” radiant barrier material to cover the underside of the entire roof

Measuring tape(s) and flashlight(s)

Heavy-duty scissors and/or utility knives

Staple guns and heavy-duty staples

Two movable support surfaces such as 2’x3’ sheets of one-inch plywood or three-foot lengths of 1″x12″ board

Collapsible aluminum ladders for attic access, and for reaching the “peak points” of the underside of the roof while in the attic

A partner will be your most important aid. Working in the attic in pairs will make the work go faster, while at the same time adding to safety.

Here is “SMARTFOILS” simple four step “recommended application” guideline:

Carefully measure the entire length of the attic roof from peak to soffit. Then return to a ground or floor-level stable surface area to measure and cut the “SMARTFOILS” radiant barrier material to size. The material comes in rolls of 100 to 462 lineal feet, depending on which “SMARTFOILS” product you have purchased. Cut and re-roll all of the lengths you will need before returning to the attic.

Start at one end of the attic, placing the plywood sheets or the 1″x12″ boards across two of the attic truss “floor” members for the creation of a stable surface. Minimize compression of the existing insulation. Create one stable surface under the roof peak and one at the soffit end so that both installers can work together.

Remember to be extremely cautious at the sides of your support surface. Stepping on an edge can tilt the work platform surface area and drop you through the ceiling drywall beneath the platform.

Working with your partner, unroll one length of the radiant barrier material from peak to soffit. Leaving two to four inches of free space at the peak of the roof, staple one corner of the radiant barrier material to the underside of the top chord of the first roof truss. Continue stapling the edge of the radiant barrier material down the truss at 6 to 9 inch intervals, stopping 2 to 3 inches from the ceiling insulation. Next, repeat this procedure by stapling the other edge of the material to the underside of the adjacent roof truss. Continue the process at the adjoining trusses until the underside of the roof is no longer visible except for a two to four inch strip at the peak of the roof.

An alternative method of installation may require slightly more radiant barrier material. You can staple the radiant barrier material to the underside of the roof decking, adjacent to the top chord of the truss. The weight of the material will allow it to drape naturally between the trusses.

Safety suggestions for installing attic radiant barrier systems:

Make sure if you use a ladder for access to the attic that it is not only stable enough, but tall enough for easy entry and exit.

Work only when the attic temperature is reasonable. In the “sunbelt” states, attic daytime temperatures can rise far above 100⁰F during most of the year. It is recommended that you install your radiant barrier system early in the morning, or let your local “SMARTFOILS” distributor handle the job for you.

Work with a partner. It makes the job go faster, and it also means that you’ll have help should a problem occur.

Use a sturdy, movable support surface. Watch where you walk, and step only on the attic trusses, rafters or on your movable support surface. Never step on the attic insulation or the ceiling drywall beneath it.

Step and stand only on the center of your movable support surface. Stepping on the edge can cause the surface to tip.

In most attics, roofing nails penetrate through the underside of the roof, so watch your head! In order to avoid potential cuts or punctures, wear a hard hat.

Be especially careful around junction boxes and older electrical wiring. Never staple over or through any electrical wiring.

The attic space must be well lighted and well ventilated. If necessary, bring in fans and extra work lights.

Direct fans upward, away from any blown-in insulation material.

Wear goggles, long pants, a long-sleeved shirt, and a particle mask or kerchief over your nose and mouth to avoid exposure to mineral fiber insulation. It is strongly suggested that you wear gloves if you are particularly sensitive to fiberglass.

Wear a utility apron or tool belt to carry staples, staple gun, scissors, utility knife, flashlight or measuring tape.

Take your time, take frequent breaks, drink plenty of fluids, and pace yourself. It is better to get the job done right over a longer period of time, than to end up with a poor quality installation. Taking your time will also reduce the chances of an accident due to fatigue or heat prostration.

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Q: Does the radiant barrier have to be airtight in order to work?
No, since you are installing a barrier against radiated heat, and not convected heat. In light of this fact, you need not cut off air motion. Ventilation from soffit to peak improves a radiant barrier system’s performance.

It will not significantly lessen the performance of the radiant barrier system if small tears and holes exist, so don’t worry if you must cut and patch around obstructions such as vent stacks, duct work or truss supports.

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Q: Can’t I just roll the material out on top of my attic insulation?

Placing the radiant barrier material directly on top of the attic insulation is not recommended. This type of installation allows dust to accumulate on the foil surface facing the roof. In time, the accumulated dust will negate the radiant barriers’ reflective effect. If this type of installation technique is performed, it is strongly recommended that a perforated product be used in this type of application. If not, problems could develop with mold due to condensation. When in doubt, ask “SMARTFOILS” if this method of application will work best for your particular installation situation.

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Q: Will heat build up in the roof and damage my shingles?

It is highly unlikely. The Florida Solar Energy Center measured the temperatures of roofing shingles above attic radiant barrier systems on hot and sunny summer days. The roofing shingles peak temperatures were only 2-5⁰F higher (depending on the color of the shingles) than the temperature of shingles under the same conditions without a radiant barrier system.

A 2-5⁰F increase in peak temperatures that normally reach 160 to 190⁰F should have no adverse affect on roofing materials that are manufactured to withstand the high temperatures to which they are frequently exposed.

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Q: Can I just roll the material out on the roof before re-shingling?

This will prevent the creation of the radiant barrier. The aluminum foil must be installed facing an open airspace in order to become a radiant barrier. Without the necessary airspace, the foil becomes a conductor, quickly passing heat by conduction from a hot surface to a cooler one.

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Q: What’s the easiest installation method in new home construction?

There are two widely accepted methods of installing an attic radiant barrier system in new home construction applications:

Attach the “Home Barrier” radiant barrier product to the roof decking before it is installed on the trusses.

-or-

Attach the “Home Barrier” radiant barrier product to the roof deck or truss chords after the roof decking is installed, but prior to the installation of the ceiling drywall.

Note: When installing a single-sided radiant barrier material, remember to face the foil side down toward the attic floor/insulation.

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Q: When will I see a payback from an attic radiant barrier system?
Computer studies conducted in the development of the Florida Model Energy Code give a very conservative indication that a typical attic radiant barrier system installed in a Florida home will offer a six to seven year simple payback, and, a 15% to 19% return on investment. “SMARTFOILS” research indicates a three to five year simple payback, with a 20% to 28% return on investment. Remember, your actual simple payback time frame and return on investment will depend on your actual energy use “profile,” as determined by all of the factors of your particular lifestyle or business energy use regimen.

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Conclusion:

“SMARTFOILS” radiant barrier systems are an inexpensive but effective way for homeowners and business owners to save energy and money. While they are not a new concept, radiant barriers have only recently been proven effective for energy conservation.

A radiant barrier system may be installed in an existing home, commercial business property, institutional facility or agricultural structure. During new construction of these buildings, installation becomes even easier to accomplish. “SMARTFOILS” “Home Barrier” and “Business Barrier” products “make cents!”

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