Radiant Barriers in Warm and Sunny Climates
This site fails to mention the energy saving qualities of Radiant Barriers. The homes that will get the most out of them are those in warmer climates with a lot of sun, and thus radiant barriers are not applicable for every situation.
A Radiant Barrier is a sheet of reflective material which is placed over the attic insulation or stapled to the bottom of attic rafters. Often times a radiant barrier can also be built into a new home by draping the material over the top of the rafters or installing a roofing surface with a radiant barrier built in.
The idea is to stop the radiant heat from a hot roof from heating up the attic insulation. Attic insulation is not enough in a hot climate, as once the insulation has heated up; it holds that heat against the ceiling and is mostly ineffective.
Where a radiant barrier is installed, the radiant heat from the roof of a house will be reflected back at the roof, keeping the insulation from absorbing the energy. Radiant Barriers are commonly made of pure aluminum and radiate as little as 3% of the energy that they absorb.
When paired with adequate attic ventilation, the effect is that the temperature of the attic is drastically reduced and energy is conserved.