Heat is transferred through three methods: conduction, convection, and radiation. For years, people have focused primarily on conduction when insulating their homes from outside temperatures. That is why we have double-pane windows and mass insulation in the walls, floors and attic. In double-pane windows, thermal gain and loss is slowed because the air space within the window conducts heat more slowly than a single pane alone would allow. The same is essentially true for traditional fiberglass and other mass insulators. These materials work by slowing the speed at which heat is conducted to a cooler surface.
RadiantGUARD® foil faced insulation is completely different. This barrier actually reflects radiant energy that can translate into heat, thereby reducing gain in the summer and loss in the winter. In fact, foil bubble insulation can reflect upwards of 95-97% of the radiant heat that strikes it making it very effective. By incorporating air bubbles, this material also reduces the conduction of the very small percentage of energy that it does absorb, making it even more energy efficient.
There are two qualities of foil faced insulation that allow it to reduced energy transfer so dramatically. These two qualities are:
High reflectivity means that radiant energy is reflected away from the surface. Radiant energy is made up of infrared rays. Though infrared rays are invisible to the naked eye and have no temperature of themselves, they have the potential to create enormous amounts of warmth when they strike the surface of a material that has qualities that allow absorption of the rays. The heat created can then spread by conduction or convection. By reflecting 95-97% of these rays and then by providing resistance to conductive heat transfer via the two layers of air space in the bubble, foil bubble insulation inhibits heat creation.
Low emissivity means that radiant barriers absorb and give off, or emit, very little radiation. Because radiant barriers absorb and emit very little heat, they insulate all materials behind them incredibly well.