How Radiant Barriers Work
What makes a good Radiant Barrier
What is a Radiant Barrier?
A Radiant Barrier is a reflective material used to defer radiant heat and slow the transfer of heat by bouncing heat waves off its shiny exterior. It is used to reduce radiant heat transfer, which is heat transmitted through electromagnetic waves, typically from the sun. For example, when the hot sun heats up your roof, a radiant barrier helps prevent hot sun rays from entering your home. All radiant barriers must include a small air pocket, either above or below the reflective material—usually as thin as aluminum foil. Without that air pocket, the reflective material would conduct the heat or versus rebounding the infrared rays back towards the source.
For A technical understanding of radiant barriers view this.
Radiant Barrier on New Construction
Radiant Barrier attached to floor joists and existing insulation
How do radiant barriers work?
Without a radiant barrier, the sun heats a roof through infrared rays, which then conducts through the roof, and increases the temperature of the attic or home. When a good radiant barrier is employed under the attic rafters, directly before the sheathing/decking (new construction), or along the bottom of the rafters (preexisting construction), a majority of the heat is reflected back through the roof, and never enters the attic at all. In fact, effective radiant barriers will block 96% of radiant heat transfer.
Radiant Barriers differ from typical insulation materials such as fiberglass. Fiberglass and other such insulation materials work by absorbing the heat and cold through conduction. This absorption then slows down the heat increase or decrease, versus reflecting as radiant radiant barriers do. In cold climates, radiant barriers are usually installed perpendicular to the floor joists of the attic, with the foil facing the living space. This is because radiant barriers work best when perpendicular and facing to the heat source, and in colder climates the goal is to redirect radiant heat back to the living area.
Why install a radiant barrier?
Good radiant barriers, like NT Radiant Barrier by rFoil, will lower your attic temperature by up to 40 degrees Fahrenheit in the summer, but affect your home year-round. Air conditioning costs are greatly reduced in warmer seasons, and likewise heating costs in the winter. On top of that, you’ll experience an extended lifespan of your heating and cooling systems due to less work load. Barriers like NT Radiant Barrier by rFoil work well alone, or as an additional layer of protection to increase the performance of existing insulation in walls, ceilings, and especially attics.