We all know that attics are the most biggest areas of heat loss in our homes. Even though you may have fiberglass or other types of traditional attic insulation, you are still not completely protected from the wide range of outside temperatures, or, as you have probably surmised, from high power bills. One problem can be that as traditional insulation ages, its R-value is depleted due to moisture and compression, thus reducing its effectiveness in protecting against temperature extremes. Unless you have recently installed new insulation, you probably have less protection than you think.
In addition to deteriorating insulation, unless you have installed a radiant heat barrier, you are also losing energy through what is called emission, or radiant heat transfer (the transfer of heat though empty space, such as when you feel the heat of the sun on your skin). Traditional insulation materials do not fully protect against this type of heat transfer, because there main job is to protect against the other two types: convection and conduction.
Your roof is constantly pounded by the heat of the sun during summer and the cold, rain, and wind during winter, and it doesn't take long before your traditional insulation system is unable to absorb any more of these weather extremes and becomes essentially useless.
How Green Energy Barrier Works
Radiant Heat: Heat transferred by radiation in the form of waves which travels through space. Radiant Heat is absorbed or reflected by the first solid object it encounters.
Reflective Insulation: a material which blocks/reflects radiant heat. Made from reflective materials like aluminum, they typically block 95-97% of the radiant heat.
Emissivity: the amount of heat which is "emitted" or radiated off of a surface to the surrounding air.
Reflect: to bend back; to give a backward turn to; especially, to cause to return after striking upon any surface; as, a mirror reflects rays of light.
There are two properties on which reflective insulations work: Reflectivity and Emissivity. First, the aluminum is reflective on the hot side, reflecting some of the heat back from where it came. Second, and most importantly, aluminum has a low emissivity of between 0.03 and 0.05. This means that only 3% to 5% of the heat is emitted to the air on the cold side. In order to benefit from both of these properties, the reflective insulation must be double sided (aluminum on both sides) and installed so that there is an air space or low density material (like insulation) on both sides. In an attic with no reflective insulation, radiant heat from the hot roof travels down through the open space and is absorbed by attic insulation, ductwork, and air handlers.The R-value is a measure of thermal resistence