Radiant Heat Or Reflective Barriers To Prevent Heat Transfer

Radiant heat is the type of heat that you feel. A radiant or reflective barrier is a thermal type of insulation that prevents heat transfer via thermal radiation. The barrier material in thermal insulation resists and reflects heat to prevent the transfer of energy through the boundaries of two systems at different temperatures. As heat is always transferred from a higher temperature region to a lower one, a heat barrier will prevent the transfer of radiant heat due to its low emitting/reflective surface. Because the material in radiant barriers reflects radiant heat that has negligible R-values, they can also be classified as thermal insulation.

Radiant barriers are typically installed in residential homes primarily to reduce cooling costs and summer heat in spaces like attics. With attic temperatures exceeding 180 degrees your insulation system is vital to your homes comfort. The highly reflective material in radiant barriers reflect, rather than absorb radiant heat, however, they do not reduce heat conduction the way that thermal insulation material does. They are more effective in hot climates and where cooling air ducts are situated in an attic. Studies show that radiant barriers can reduce cooling costs dramatically by more than 40%. The effectiveness is also matched in the winter time as temperatures dip below freezing.

How Does it Work?

How Does it Work?

By a combination of convection, radiation, and conduction, heat travels from a warmer area to a cooler area.

  • Within a material heat flows by conduction from a warmer location to a cooler location.
  • Convection heat transfer occurs when a liquid or a gas like air, is heated, causing it to become less dense and rise up. As the gas cools it becomes denser causing it to fall.
  • Radiant heat travels away from any surface in a straight line and is absorbed by anything solid.

Most insulation materials are used to slow down conductive heat flow, and convective heat flow to a lesser extent. Reflective insulation systems and radiant barriers are used to reduce radiant heat.

In order to be effective, it is important that the reflective surface of the barrier directly faces air space and should be installed in such a way that dust accumulation is minimized as dust on the surface will reduce the reflective capability of the barrier. It works best when it is installed perpendicular to radiant energy, such as from the sun, striking it. In addition, the greater the difference in temperature between the two sides of a radiant barrier, the greater the benefits will be.

Different Types of Radiant Barriers

Most radiant barriers consist of highly reflective materials such as aluminum foil covering both sides (or one side) of certain substrate materials including plastic film, cardboard, air infiltration barrier material, or oriented strand board. Some radiant barriers are fiber reinforced to increase ease of handling and durability. They can be combined with other types of insulation materials to form reflective insulation systems. In such combinations, radiant barriers can act as facing material for thermal insulation.

The effectiveness of radiant barriers depends a great deal on proper installation and therefore should ideally be installed by a certified insulation experts who are aware of building and fire codes and how to employ the best safety precautions during and after installation. It is easier to incorporate into a new home but can also be installed in existing structures, especially in open attics.