If you want to maximize the energy efficiency level of your attic and of your whole house, one key element in accomplishing that is to install a high-quality radiant barrier on your attic ceiling.

A radiant barrier will prevent excessive heat build up in your attic. And when your attic is overheated, that heat can seep down into your living spaces below, making it take longer and cost more to keep your home cool during those hot Lafayette summers.

HOW DOES A RADIANT BARRIER WORK?

The large majority of the heat lost from your home in the cold months exits through your attic – that’s why insulation on the attic ceiling, walls, and floor are so important. But during the hotter months, large amounts of heat enter your house through the roof and attic and seep down into the rest of your home to make cooling more difficult and more expensive – that’s the problem that a radiant barrier can solve.

Radiant barriers consist of layers of foil, usually made of aluminum, that is highly reflective and will literally “bounce” heat back out of your house as it tries to stream in through the attic ceiling.

And besides its extremely high reflectivity, the materials used on the upward facing side of radiant barriers also possess extremely low “emissivity.” You’ve probably heard of how “low-E” windows can keep excess heat out of your house – the low-E materials radiant barriers are made of do the same thing on the top of your home. That is, heat will not easily transfer through a radiant barrier (or low-E window pane) but will mostly reflect backwards off of it.

A radiant barrier will help you increase the comfort level of your home and lower your energy use in every season of the year. In the summer, it reflects off the heat so your house stays cooler; in the winter, its low emissivity helps to trap heat inside your home so it’s easier to keep at a comfortably warm temperature.

To reach your home’s full energy efficiency potential, you need more than just a radiant barrier. You need to air seal the attic, install insulation throughout your home (attic, walls, ceilings, floors, basements, crawlspaces.) You also need a proper ventilation system, with vents and fans in all the right places. BUT, a radiant barrier boosts your effective overall R-value to new levels that you couldn’t reach without it.

THE THREE KINDS OF HEAT TRANSFER

The key background science to understanding how and why a radiant barrier works is all about the different ways that heat in transferred (or blocked or slowed.)

Radiant barriers basically block/slow heat transfer AND redirect heat, thus “transferring” it in the opposite direction – away from your house!

Heat can move by means of conduction. That is, when two objects in direct physical contact, heat will transfer from one of them and into (and through) the other. This is the least effective means of transferring heat, and thus, the most effective means of blocking/slowing heat transfer – depending on the materials in contact. Low-e materials that radiant barriers are made out of will tend to block heat more than to let it transfer through by conduction.

Heat can move by means of conduction. That is, when two objects in direct physical contact, heat will transfer from one of them and into (and through) the other. This is the least effective means of transferring heat, and thus, the most effective means of blocking/slowing heat transfer – depending on the materials in contact. Low-e materials that radiant barriers are made out of will tend to block heat more than to let it transfer through by conduction.

Finally, heat is transferred most rapidly and effectively by thermal radiation (radiant heat). This is the kind of heat transfer that occurs when the sun warms up your body even while the air outside is still cold or when a radiant heater does the same. The heat is transferred directly from the source of heat to the object heated without having to first heat another object or the intervening air. That’s great when you want to get warm, but not when heat radiates in massive waves into your attic! A radiant barrier reflects that radiant heat back out – and because counteracting radiant heat is the most important facet of what a radiant barrier does, that’s what it takes its name from.