Radiant Barrier is unlike mass insulation which only slows down or resists heat transfer. RB 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.