"COMFORTABILITY" is the most important element for mankind. The major contributor to comfort is temperature. Heat is the source of temperature changes, which can be transferred in three way: Conduction, Convection and Radiation. The transfer of heat occurs from a warmer to a colder region. Conduction and Convention can only be transferred through a medium or physical contact, whereas Radiation can be transferred across a perfect vacuum as the radiant energy travels in straight line through space. As shown in Diagram I*, in a close environment, the contribution of Radiation is the highest among all sources of heat. The roof is the surface of a building that is most exposed to solar radiation and the solar gain absorbed by the roof is directly transmitted down to the attic space. When a radiant barrier is placed underneath the roof covering, leaving an air space, almost all radiant heat will be eliminated. In cold climate regions, the radiant barrier holds the heat inside the building closed environment. Installing a Radiant Barrier is the best solution to save energy, either in a hot or cold climate region. The Radiant Barrier performs at its best if combined with other roofing solutions that provide a batten cavity space and ventilation.