The Tucson Institute for Sustainable Communities is a non-profit educational organization based in Tucson, Arizona, which works to cultivate vital and sustainable communities that are resource efficient, ecological, affordable and equitable. Sustainable Sources 1994-2001. A radiant barrier is a layer of metallic foil that blocks radiated heat, assisting in the energy performance of a home. This system provides air movement under the roof that washes the underside of the roof with air that is exhausted out the top of the roof through the ridge vent. A radiant barrier is used in our area principally as a cooling strategy.
Buildings gain heat in three ways - conduction, convection, and radiation.
A radiant barrier is useful in preventing heat gain from radiation. Emissivity is an indication of a surface's ability to emit heat by radiation. The lower the emissivity, the better the radiant barrier qualities of a material. Emissivity is measured on a scale of zero to one. A radiant barrier is typically placed beneath roofs in our area to block the heat gain radiating from hot roofs.