Radiant barriers reflect heat away during the summer and reflect it in during the winter. They are easily added to existing homes at little cost.
During college, I spent summers fighting forest fires in Northern California. At all times, we were required to carry with us a little pouch containing a fire shelter, which was basically a giant aluminum bag you were supposed to crawl into in the event you were surrounded by the fire and had to weather it out. As long as the fire doesn't touch the tent, most of the heat would be reflected away, saving the life of the person inside.
Radiant barriers use the same heat reflecting properties of aluminum installed in the attic of a home to reflect out the sun's radiant heat during the summer and reflect some heat back in the home during the winter.
According to LP Corp, a leading manufacturer of radiant barriers, homes with radiant barriers can save up to 17% on monthly home energy costs. In fact, radiant barriers are REQUIRED in newly constructed homes in ten of the 16 climate zones in California.
I recently visited a new home construction in North Carolina with the radiant barrier installed. In addition to the potential energy savings, it looked clean and increased the reflect light and visibility of the attic.
For new construction it makes sense, as you can by roof sheathing with the aluminum already attached to the bottom. It installs just like a regular roof, with the added benefit of a radiant barrier.
For existing construction however, there are options of adding the radiant barrier. RadiantGuard sells their Ultima product that can be stapled to the underside of your rafters, and for most homes would come in under $200 dollars.
But does it work? Some studies say it does. Does anyone have any firsthand experience? And which would be better, adding more insulation to an attic or installing a radiant barrier?