what is radiant barrier | buy best radiant barrier foil insulation
TRANSCRIPT
What is Radiant Barrier?
Radiant Barrier
• Radiant barrier is a highly reflective material, typically madeof aluminum, which blocks the transfer of radiant heat byreflecting it away from its surface offering a permanent wayto reduce your monthly utility costs.
• Radiant barrier foil insulation systems BLOCK radiant heatenergy instead of absorbing it like fiberglass insulation.
• Because this foil insulation is unaffected by humidity, it willcontinue to perform at a consistent level no matter howhumid the seasonal climate.
Heat Transfer Methods
• Conduction: this method of heat transfer occurs when two solidobjects touch each other. The heat is transferred between the twoobjects via molecular motion. For example, if your hand touches thesurface of a light bulb, the heat from the glass will be transferred toyour hand.
• Convection: heat that moves through fluids, such as water, risingheated air, or steam is doing so by the convection. In air, convectionresults in rising heated air causing the cooler air to drop to the floor.This creates what is called a free convection loop. One can createtheir own convection loop by using a fan to circulate the air in aroom. This creates what is called a forced convection loop.
• Radiation: heat that is transferred by infrared waves is calledradiation. These rays are invisible to the naked eye and are notaffected by air flow. Stepping out into the sun on a hot day, you willfeel your skin heat up from the heat radiating from the sun. And youwill still feel these heat rays regardless of how windy it is outside.
How Conventional Insulation Works
• Fiberglass and blown-in cellulose insulation aremanufactured with air spaces inside designed to reduce heatconduction through the material. They also restrict heattransfer by convection by trapping air flows and lowering aircirculation.
• Similar to fiberglass and blown-in insulation, some foaminsulations, comprised of hydro chlorofluorocarbons (HCF),also absorb conductive and convective heat. However, HCF'sfound in some foam insulation products have been found tobe extremely potent greenhouse gases and are being phasedout by the United States over the next 23 years.
How Radiant Barrier Works
1. Reflectivity = The natural reflectivity property of a reflectivesurface facing a heat source across an air space allows thealuminum to REFLECT radiant heat back to the direction fromwhich it came.
2. Emissivity = All materials have emissivity's ranging from 0%to 100%. The lower the emittance percentage of a material,the lower the amount of radiant heat radiated from itssurface. The naturally low emissivity property of a reflectivesurface facing an air space results in very low emittance ofheat from itself; it does not radiate much of its own heatfrom itself.
Why Radiant Barriers REQUIRE An Air Space
• Because a radiant barrier requires an air space on at leastone side of itself to be able to BLOCK radiant heat, aradiant barrier CANNOT be installed directly underneathroofing materials where no air space exists.
• For example, if you install a radiant barrier on top of roofdecking between the felt paper and asphalt shingles, itwill NOT provide any benefits as the radiant heat wouldbe transferred through the shingles, through the felt tothe radiant barrier, and through the roof decking into theattic space.
