Why Does Radiant Barrier Work? 

What makes radiant barrier foil so effective in reducing energy bills? Radiant barriers work by blocking radiant heat from being absorbed into our homes, garages, barns, etc. resulting in a more comfortable and energy efficient space.

In theory if all of our homes were under the shade of a tree, we wouldn't need radiant barriers. Since that is not the case, radiant barrier foil is the next best thing to naturally occurring shade. Simply put: radiant barriers reduce the amount of heat entering the home/building. Reducing the amount of heat gain helps to reduce the energy needed to remove the heat (air conditioning) and makes the living space more comfortable.

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In essence, AtticFoil® radiant barrier is like a shade for your house that reflects the infrared energy (heat) emitting from the sun away from the home.  

You probably already have some form of radiant barrier at work in your home.  For example, do you have the shiny silver flex ducts in your attic? These are insulated tubes with a radiant barrier covering. The radiant barrier reduces heat from entering the duct work and effectively makes the R-Value of the insulation greater. Conceptually, this is what we are trying to achieve for your whole attic.

How Does Radiant Barrier Work?

Infrared, or radiant heat, is invisible. Think of a mirror; if you hold it up to the sun, you can reflect the light on your arm. You see the light, but you feel the radiant heat.  At night when the sun goes down, your home is instantly easier to keep cool, right? Why? Because when the sun went down the radiant heat gain on the home was reduced. So even though the air temperature may only drop a couple of degrees, there is a big difference is how the surfaces feel.

Standard Staple Up Method for Radiant Barrier

Over the Insulation Method for Radiant Barrier

How Well Does Radiant Barrier Work?

How well a radiant barrier works depends on several things. Generally the more roof surface you have, the greater the impact. For example, installing foil insulation on a single story ranch style home will have a greater impact than a stacked two story home with a small attic. Remember, your home is essentially a box with five basic exterior sides. The greater the roof portion (or top side), the greater potential impact overall.

Does Radiant Barrier Promise Drastic Results?

How much electricity would you save if your roof was shaded? This is realistically the most you will save by installing a radiant heat barrier in your attic.  Nothing more, probably a little less. On a 90ºF day are you still going to run the air conditioner? Yes, it's 90°F!

After installing a radiant barrier your air conditioning will run less and more efficiently, but it will still run. However, on a 75ºF day the radiant barrier might just keep you from having to run your A/C at all. Remember, reflective foil insulation is like shade, so the more coverage you have, the better your results. 

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How Much Will I Save?

As we mentioned above, it really depends.  Generally you can expect a 5 to 25% savings; one story ranch-style homes typically have the highest percentage savings. No matter what the percentage is, the dollar payback remains consistent. On a two story home, you might have only half the savings compared to a single story home but you also probably only installed half the amount of foiland had a lower total installation cost.  So no matter your investment, it will match your return.  

For more information see our article on Expected Savings with a Radiant Barrier.

Are There Different Types of Radiant Barrier?

Yes, but a foil product will work much better than a radiant barrier paint, ceramic paint additive or micro-spheres.  Also, sheets of foil are more practical and economical that shredded pieces of aluminum (radiant barrier chips) and more effective because they allow for full coverage and easy access to your attic, if needed.  

Why bubble foil products and radiant barrier with insulation attached aren't necessary in a standard attic application.