How does Radiant Barrier work?
Radiant Barrier is unlike mass insulation which only slows down or resists heat transfer. Radiant Barrier reflects heat. Heat always goes cold by natural law—the problem is how to keep the heat in in the winter and how to keep it out in the summer. There are three ways in which heat goes from warm spaces to cold spaces: CONDUCTION is direct heat flow through a solid object such as a wall or a ceiling. CONVECTION is heat movement through air, occurring when air is warmed. The warm expands, becoming less dense and rising. RADIATION is the movement of heat rays across air spaces from one warm object to a cooler object. The heat we feel from a wood stove or a quartz space heater is radiant heat. ALL OBJECTS AND BODIES GIVE OFF RADIANT HEAT. Even the insulation in your attic gives off radiant heat to the cold attic space in the winter, and to the living space in the summer. Regular insulation won’t stop radiant heat loss. Radiant heat must be REFLECTED with a radiant barrier.
A. Radiant barrier is reflective sheeting that is stapled between the roof rafters or trusses. It is sometimes draped, loosely, over the rafters prior to the roof sheeting being installed. It is now available attached to plywood sheeting. The radiant side faces down or towards the attic. The majority of heat gain in any attic is from the sun. This is known as radiant heat, as it is radiating from the sun. As sunlight beats down on a roof, the energy (radiant energy) that penetrates the roof covering and decking converts to heat. Exactly like sunlight coming through your window. The one difference is that some of that sun energy coming through your window is actually light because the window is clear. Your roof does not allow light to pass because it is opaque. Therefore, there is a much larger amount of heat generated in your attic than in your house. Radiant barrier is very effective in reflecting that heat back through the roof before it heats up your attic. The end result is a coole
