BY RHINOHIDE
What is a Radiant Barrier?
A radiant barrier is a reflective insulation that can effectively block most of the heat entering or leaving your living space. Stopping radiant heat transfer is the surest means for reducing your heating and cooling needs. In summer, less radiant heat in your attic means that your air conditioning system will run more efficiently. In winter, when you want to keep the heat in, a radiant barrier can help your heating system run more efficiently by reflecting the heat inward.
"Radiant heat transfer is seldom discussed but is a dominant form of heat transfer that traditional insulation does not block."
Traditional insulating materials such as fiberglass, cellulose, and Styrofoam are able to absorb or slow down convective and conductive heat transfer. Radiant heat transfer is seldom discussed but is a dominant form of heat transfer that traditional insulation does not block. The chart below explains the differences between these 3 types of heat transfer.
Radiant heat moves in straight lines, like light. It doesn't need air to travel. Think about how the sun heats your attic—sunlight hits the roof, that heat passes through the roof and warms the attic space. The warmth comes directly from the roof surface getting hot and sending that heat downward.
Conduction is how heat moves through solid materials when they touch. For example, if the sun heats your roof, that heat travels from the hot shingles to the wood underneath by direct contact. The top layer warms up first, then passes heat down to the layers below, one part at a time.
Convection is how heat moves through fluids like air or water. Inside a house, when warm air from a heater rises and cooler air sinks, it creates a cycle. Warm air goes up to the ceiling, cools down, then falls back down to be heated again. This movement spreads heat through the room.
In your home, radiant heat is generated from charged particles converted into electromagnetic radiation. Radiant heat sources include sunlight streaming in a south or west-facing window, a fireplace, or a radiator linked to a central boiler. It moves through the air without actually heating the air. The objects that are in the path of the charged particles, however, absorb the energy and heat up, radiating heat to other objects (like people) in the room. Everything in proximity to that space feels warmer.
Hot and Cold Facts
Radiant barriers are usually installed in the attics of homes. In warmer climates, radiant barriers are usually found under the roof rafters, reflecting back the heat generated when the sun meets the roof. Since the amount of heat meeting your home’s insulation has been largely blocked, the heat of the attic’s air temperature is greatly reduced. Anyone who has been in an attic on a hot, sunny day can appreciate this. Radiant barriers, then, protect ductwork and any items stored in an attic.
In cooler climates, radiant barriers work to prevent heat from the lower levels of the home from escaping. It is important to have a tight air seal in the attic at all times but, in combination with a radiant barrier, homeowners are going to significantly save on heating bills.
Benefits of adding a Radiant Barrier
Benefits of adding a Radiant Barrier
Adding a radiant barrier to work along with your current insulation can have great benefits.
What to Look For:
Radiant barriers come in rolls of thin, highly reflective material, usually over 90% aluminum. The reflectivity of a radiant barrier should be as close to 100% as possible, and the emittance level should be close to 1-3 %. This means that less thermal radiation is emitted, and the heat from the roof will be reflected back. Look for a barrier with a denser, heavier weight and tensile strength – preferably one that has a woven fiber to prevent ripping and tearing upon installation. It will also discourage rodents from nesting because they can’t use it for nesting materials.
There are so many benefits to installing a high-quality radiant barrier in your home that many communities actually require it. In moderate zones, it won’t have the money-saving capabilities of colder and hotter climates, but a radiant barrier is a good investment wherever you make your home.
