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What is reflective bubble foil and reflective radiant barrier insulation?
Reflective foil insulation products also known as radiant barrier foil insulation, reflective bubble wrap insulation, bubble foil insulation, double bubble foil insulation, and reflective bubble insulation are a class of insulation products designed to stop the transfer of radiant heat. There are many variations of these products. Some good, some not so good. But the objective of stopping the transfer of radiant heat is always the same. Reflective foil and reflective radiant barrier insulation is a permanent solution to lowering energy costs. Reflective foil insulation creates a radiant barrier system that reflects radiant heat instead of absorbing it into the building structure. This type of insulation is not affected by moisture or humidity and performs at the same level no matter what the outside weather conditions. People are more familiar with the more traditional forms of insulation materials like fiberglass or cellulose insulation. The products work to slow down conductive and convective heat transfer. The other form of heat transfer and a dominant one is radiant heat and it is only controlled by using reflective foil insulation.
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What is a reflective radiant barrier?
Radiant barriers are achieved by using reflective foil insulation. And unlike other insulation materials, radiant barriers reflect radiant heat energy instead of absorbing it. Testing data shows that in the hot summer months, up to 93% of heat gain is absorbed by radiant heat energy. In the winter months, 65-80% of heat loss through side walls is due to radiant heat loss. Using reflective foil radiant barrier insulation is the only way to help stop the loss or gain of radiant heat energy.
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How does reflective foil insulation and radiant barriers work?
In order to understand how reflective foil insulation and reflective foil radiant barrier work, it is important to understand the reflective properties of pure aluminum. Pure aluminum, with the exception of gold and silver is the most reflective material on earth. Aluminum naturally reflects 97% of radiant heat or radiant energy. If your goal is to stop the transfer of radiant heat, reflective foil insulation is the only insulation material to achieve this.
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What is radiant heat and how is it transferred?
In order to understand radiant heat and how it is trnsferred, it is important to also understand all the forms of heat transfer. There are three ways in which heat is transferred. The first is Conductive Heat. Conductive heat transfer works by direct contact. On a basic level this is the same as wrapping your hands around a hot cup of water. The hot water has heated the material of the cup by being in direct contact with the cup. Now, your hands are being warmed up by being in direct contact with the warm cup. The second form of heat transfer and most common in a modern buiding system is Convective Heat. On a basic level, this is the same as putting your hands above the hot cup of water but not touching it. You can feel the heat in the form of steam. Conductive heat transfer is the same as central heating or forced air systems wheare a furnace heats air to a certain temperature and then this air is forced or blown into a living space thereby warming the area. The third type of heat transfer and type that we deal with is Radiant Heat tranfer. On a basic level, this method of heat transfer is the same as stepping outside on a bright, sunny winter day. Although it is cold outside you can fell the warmth of the suns rays on your face. You ar feeling radiant heat transfer. Radiant heat from the sun is being transferred and your body is absorbing it. Now that all three types of heat transfer have been explained, hopefully it will be easier to understand how insulation and insulation systems work.
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I did not know that there were three modes of heat transfer. Why is this important?
Heat transfer inside and throughout a building envelope occurs by conduction, convection, and radiation (radiant heat transfer). This is important for two reasons. Firstly, each type of heat transfer occurs in different proportions. Radiation or reflective heat transfer accounts for up to 75% of all heat loss through a building envelope. Secondly, different types of insulation protect against different modes of heat transfer. To stop radiant heat, use a high quality reflective insulation product. Fiberglass and cellulose insulation do a good job in reducing conductive and convective heat transfer. They however, do a poor job in preventing radiant heat transfer. Radiant heat is either absorbed or reflected and cannot be reflected without using reflective foil insulation.
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Why is controlling radiant heat gain and loss so important?
Radiant heat is energy. It has no temperature as it travels through your living spaces; however, when this energy strikes an object, it is absorbed and increases the temperature of that object. The object then emits this energy out the other side causing heat loss or heat gain through the building envelope. A whopping 75% of the heat transfer in your building envelope is in radiant heat energy. Reducing heat gain and heat loss due to radiant heat can dramatically increase your comfort and reduce your energy costs.
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Can you give me an example of all the heat transfer systems at work together?
Absolutely, and the two examples are the most compelling reasons reflective aluminum foil insulation works but works perfectly in the correct applications despite the lack of residential focus in past years. The two examples where reflective aluminum foil insulation have been used successfully for many years is in the aeronautical and space exploration industry. Metalized aluminum has always been issued in airplances and space shuttles, and even in space suits for astronauts. Nasa credits reflective insulation technology for allowing astronauts and their equipment to withstand the extremely harsh environment of space where temperatures range from 200 degrees F to -200 degrees F. Using an example of reflective foil insulation at work with other insulation systems is fitting to do in the harshness of space. An astronauts spacesuit responds to the three types of heat transfer in the following ways. First for Conductive heat transfer, the thickness of the spacesuit and the space between the outside of the spacesuit and the astronaut inside controls conduct heat transfer just like fiberflass insulation (the thicker the better) in wall cavaties controls heat gain or loss. Convective heat transfer in this example would be controlled by the temperature control system of the spacesuit. Heating up or cooling down the air in a spacesuit is the same as any envelope no matter the size. Furnace and air conditioning unit is always rated to square footage of the building envelope. The third, and last type of heat transfer system is Radiant heat transfer. Lining the inside of spacesuits with metalized aluminum foil repels the enormous radiant heat gain from the sun. In time periods with no sun and extremely cold temperatures the metalized aluminum helps trap the radiant heat in the spacesuit or building envelope. Obviously in the case of the aeronautical industry and airplanes the principles are still the same. The size of the building structure or envelope does not matter.
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How can I determine what reflective foil or radiant barrier insulation is the best to buy?
Comparing reflective foil and radiant barrier products is relativeley easy if you look for the following indicators. For radiant barriers used in attics, basements, garages, living spaces or any other relevant application, you should always have a no tear product. Look at material makeup. To be considered a premium product, there should be three layers of material. Two layers of reflective aluminum foil and a layer of no tear material. Premium reflective foil bubble insulation products should have two layers of high strength polyethylene bubbles and two layers of either reflective foil or poly product. Look for compression strength to compare bubble products. For any uder concrete applications or radiant heat applications, all products should have a white or poly side. Look for a patented product. We offer a patented product. All products should conform to the ASTM E-84 Fire Rating Test. And lastly, and usually considered most important is price. The price for reflective foil insulation and reflective radiant barrier insulation should be in-line with the product quality. As with any purchase, always buy from a company that is an expert in their field and who offers a wide range of products for various applications at competitive prices.
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How does fiberglass insulation compare to reflective foil insulation?
Fiberglass insulation, which is very effective for its uses, depends on R-Value or resistance alone to insulate against summer heat gain and winter heat loss. Thin layers of fiberglass are due virtually nothing to stop reflective heat or energy transfer. Fiberglass insulation is also affected by changes in humidity or moisture levels. A 1 to 1 1/2% change in the moisture content of fiberglass insulation can result in up to 36% decrease in performance. Unlike fiberglass insulation, our reflective foil radiant barrier products are not affected by humidity and moisture changes and will continue to provide energy savings and insulation value no matter what the moisture level is. Reflective foil radiant barriers also have additional uses that fiberglass insulation is useless for such as radiant heating systems or any under or over concrete slab applications. In these uses reflective foil insulation is the premier if not only choice to use.
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Where can I go to find testing and approvals for reflective foil and reflective radiant barrier insulation systems?

Texas A & M University

Oak Ridge National Laboratory

State of California

Metrolpolitan Dade County Florida Building Code Compliance Department

Tennessee Technological University

Tennessee Valley Authority

United States Testing Company

Southern Building Code Congress International

International Conference of Building Officials

Building Officials and Code Administrators

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What are the two terms commonly encountered when judging reflective insulation?
As R-values are used to measure the effectiveness of mass insulation, Reflective and Emissive ratings are used to measure the effectiveness of reflective insulation with radiant heat. A high Reflective value helps block more radiant heat and a low emissive value means the insulating material releases less of the heat that it absorbs. Better performing reflective insulation like all of the products offered at Insulationstop.com,are made from 99% pure aluminum for very high reflectivity and very low emissivity.
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Why must reflective insulation be installed adjacent to an air space?
An air space allows heat to be converted into radiant energy. Installing reflective insulation adjacent to an air space allows this radiant energy to be reflected away from the building envelope. This is one of the primary reason for the bubbles in reflective foil insulation, especially in underslab an radiant heat applications. Always try and achieve the maximum airspace possible within your applications constraints. Using firring strips is generally the easiest and most efficient way if no adequate airspace is present.
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Depending on where I install reflective insulation my assembly r-value will be different. Why is this?
The R-Value of a horizontal assembly (e.g stud wall) using our premium reflective foil insulation is 6.8. Downward R-Value (e.g. crawlspace or attics) is 10.6 and Upward R-Value (e.g. ceiling) is 5.3, tested in accordance to ASTM C1224. This effect is caused by the direction of convective airflow around the assembly.
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How does condensation effect reflective insulation?
Reflective foil insulation is among the few insulations that is not affected by humidity. Its insulating value remains unchanged whether in a dry or very humid climate.
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Can reflective insulation be used with other conventional insulation?
Yes, reflective foil insulation used in conjunction with other conventional insulation creates a highly energy efficient insulation combination. In theory and in practice this is where all types of heat transfer are dealt with. Together, both types of insulation can substantially help reduce energy costs.
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How does reflective foil insulation and radiant barriers keep heat in in the winter and help keep heat out in the summer? A great example of stopping heat transfer in hot and cold temperature is the Thermos Bottle. Radiant barriers and reflective foil insulation in conjunction with other insulation types creates the same effect. Conductive and Convective heat transfer is slowed by the airspace and tight seal. Radiant heat is slowed by the reflective surfaces. Whether the Thermos Bottle starts off hot or cold does not matter because the all forms of heat transfer have been contained.
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Can I use reflective foil insulation to insulate around my foundation wall?
Absolutely, you can and should use foil insulation to insulate around your concrete or brick foundation walls. You should use our Concrete Barrier Foil product. Basements and foundation walls are typically large areas because of their contact with the earth are primary sources of heat loss. Ultra CONCRETE BARRIER FOIL excels in this area. Its impervious to moisture and insect infiltration and creates a barrier between the outside earth and your basement wall. Its a vapor and radon barrier as well. The bubbles act as a capillary break that stops moisture intrusion. The reflective foil barrier is surrounded by the patented bubble/foil/bubble design. CBF™ protects the waterproof coating used on the dirt side of the wall while back-filling the soil.
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What is the R-Value of your radiant barrier insulation?
R-Value or resistance to temperature gain or loss is measured by a few criteria. The direction of the heat flow coupled with the number and size of the airspaces and the product itself can give you a typical R-Rating. More often than not, radiant barrier products are installed over or on top of existing fiberglass or other forms of mass insulation. R-Value of the radiant barrier product is not an issue. The reflective radiant barriers ability to stop the transfer of radiant heat is where you get the most energy savings.
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I've heard that I should not use fiberglass insulation in crawlspaces or basements. Is reflective foil insulation a good product to use?
You are correct. Fiberglass insulation loses a considerable amount of its insulation value when exposed to even minimal moisture levels. Basements and crawlspace areas have notoriously high moisture content. And with the current problems concerning mold, any product that retains moisture is not recommended. Reflective bubble insulation is thin, has high r-values and works great in space limited areas.
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