What is a Radiant Barrier

A radiant barrier is a type of insulation that works by blocking radiant heat energy as opposed to the conventional mass insulations whose operations are pegged on absorbing the heat energy. Radiant barriers use reflective types of foil like sheets that are made from blend of highly engineered metals, plastics and heavy duty fiber threads for increased strengths. To understand the workings of radiant barriers and how you can benefit from reflective insulation, the following article has been prepared for your knowledge and understanding.

How Heat is transferred?

You will understand the operations of a radiant barrier when you first understand how the three methods by which heat is transferred from warm spaces to cold spaces. These include:

CONDUCTIVE HEAT TRANSFER

Which is the flow of heat through fluids or solids

CONVECTIVE HEAT TRANSFER

Which is when heat moves through air when it is warmed

RADIANT HEAT TRANSFER

Which is the movement of invisible heat rays from warm surfaces to cold surfaces through space.

Difference between reflective insulation and conventional insulation

There is a difference in how reflective insulation works compared to the conventional insulation, which involves the use of products such as foam insulation, cellulose insulation and fiberglass insulation. Conventional insulation products work by slowing down or simply offering resistance to the flow of heat energy. These materials actually do not block the heat from passing through but they only slow it down. Radiant barriers also work almost in a similar manner like the conventional insulation products by reducing the amount of heat that gets into the house from the attic. The only difference is how they reduce the amount of heat flow. With a radiant barrier, the amount of heat is reduced across the air space that is adjacent to the radiant barrier. The main function of conventional insulation is to trap still air within the insulation hence reduce the rate of heat transfer by convection.

It is important to remember that traditional attic insulations have typical r-values which work to slow down the conductive heat transfer. Radiant barriers on the other hand reflect away the radiant heat. Both these two types of heat usually try to gain access to your house during the hot months of summer.

When the sun heats up the roof, heat is transferred by radiation (radiant heat) to the attic insulation. At this point, the heat then turns to conductive heat to travel from the attic region into your house. This is why you need both attic and radiant insulation in your home.

Conventional insulations are also rated with an R-value and since the performance of radiant barriers depend on a number of factors; R-values are not used when referring to them. It is also important to remember that conventional insulation alone does not offer adequate insulation for radiant heat transfer.

What Qualifies as a Radiant Barrier?

For a material to be considered as a radiant barrier, it must have a reflectance of 90% or more and an emission of 10% or less. This is according to the United State Department of Energy regarding classification of products for the purposes of measuring or providing incentives.
A radiant barrier uses foil like surfaces to reflect rays back to their source. The main properties on the surfaces of such barriers which enable them to reflect away heat:

Reflectivity

The ability to cause to return after striking any surface

Emissivity

Amount of heat radiated off from the surface of the material to the surrounding air.

The ideal radiant barrier products have reflectance of over 97% and emission levels of just about 3% which exceed the minimum classification by the US-DOE.

For proper functioning of the radiant barriers, the reflective side must be installed at an angle of ¾” and they must face the open air space. The following are some of the common areas where radiant barriers would be installed:

For more information on the installation of radiant barriers in your home, kindly contact us today. It will be our pleasure to give you the information you need.

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