The keys to this system are the use of builder's foil material and the airspace, which combine to block about 95 percent of the heat that is radiated down by the roof so that it can't reach the insulation, which would heat up and radiate this warmth into the living space. If your house is already relatively energy efficient, you will save more by adding a radiant barrier because the roof and attic make up a larger portion of the current cooling load. Take a look at your utility bills for the year and see how much they increased when you used the air conditioner. This is a good estimate of the cooling load. Now figure that you can cut that by 8 percent to 12 percent, and you've got an idea of the savings.
Radiant barriers are inexpensive and easy to install.
You can buy foil for the average home for a couple of hundred dollars and could install it yourself during a weekend. After flushing the toilet, when the tank is almost filled up there is a noise. The wire and bulb appear to be vibrating. Fortunately, a toilet has only a few moving parts. And usually, there is only one of them that will make noise as the toilet tank nears the full mark.