IR Barriers

How does Reflective Aluminum Foil Insulation work?
Reflective Aluminum Foil Insulations don't absorb heat, they block the flow of radiation. Installing Reflective Aluminum Foil between the heat source (sun) and an existing insulation will improve the effectiveness of the R-Value rated insulation. The reason is that only little part of the heat is now hitting the R-Value rated insulation and therefore, it will take longer for it to absorb 100% of its potential thereby holding the heat longer before passing out the back side into the room. Reflective Aluminum Foil reflects up to 97% radiant heat striking its surface.

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Reflective foils are available in many forms and most products used in the residential and commercial marketplace are thin sheets of plastic film coated with reflective aluminum. This technology is not new by any means. If you have cooked food in advance for a meal, you probably kept the food warm by covering it with aluminum foil. As we all know, it does a superb job of bouncing the invisible infrared energy light waves back into the food.

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On the other hand, aluminum foil is an
excellent radiant barrier. It has a low emissivity (0.05),
therefore, it eliminates 95% of the radiant transfer
potential.
Aluminum foil is a good thermal conductor. Conse-
quently, it has an extremely low R-value. However, if
it is placed between materials that are attempting to
transfer thermal energy by radiation (rather than con-
duction) and if it is separated from these materials by an
air layer, the foil effectively eliminates the normal
radiant energy exchange across the airspace. This is the
operating principle of radiant barrier systems and it often
can be used to reduce the flow of heat through building
components.

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Try this out to test metallized plastic film’s ability to take the heat: Hold up the metallized
plastic to a spot flood lamp and watch the heat of the lamp melt the plastic film. Perform the
same with WeatherTite RigidBoard(or aluminum foil) and see how the surface of the foil is able to dissipate the
energy and not affect the material in any way. This test alone shows how ineffective the
metallized plastic is at reflecting the radiant energy, which in turn costs money in higher utility
bills.

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