A. I know that this is one of the best strategies for keeping a home more comfortable in summer, it is a great do-it-yourself project, it doesn't cost a lot for the materials, and you'll save a lot of energy no matter how old your house is. It's also a technique that's been very popular for the a number of years, and uses building material similar in concept to what's been used for 50 years or more.
Let me explain. The basic strategy is to block the sun's radiant energy that brings heat into your attic. Hot weather can easily bring attic air temperatures to 150 degrees or more - heat that transfers downward into the attic insulation and then on into the home's living space. The radiant barrier relies on two steps - the use of inexpensive builders foil material, and an air space between the foil and the roof. You should also have good soffit and ridge vents so the hot air has a way to escape.
Builders have been using foil products for many years to keep attics cool, but it was the discovery that coupling the material with an air space could dramatically improve the process that has brought the radiant barrier such popularity. I know many people who have bought foil at a building supply store and spent a weekend installing it without too much trouble (though it's a lot more comfortable to install this material in cool weather when the attic air temperature isn't so hot). The nice thing is that unlike insulation, which really needs a continuous barrier to work properly, you'll still have an effective conservation strategy if you don't do a totally thorough job of reaching every part of the attic. But I also know people who preferred to hire a contractor to do the job since working in the tight confines of an attic isn't necessarily one of the easiest things to do.
There also is some wintertime benefit to this strategy, though the real savings come in hot weather. You can get all the details on attic radiant barriers at www.fsec.ucf.edu/en/publications/html/ fsec-en-15/.
Experience with this product has taught me one thing I need to repeat here: research has found that in a hot climate like the southeast United States, you can save somewhere between 8 and 12 percent of your annual cooling costs. I've talked to many contractors and salespeople who promise huge savings that just aren't possible. Look at your old energy bills and calculate how much they go up in hot weather when you use air conditioning, then figure you could cut this amount by 8 to 12 percent. It's a pretty good savings (though not nearly as much as some companies say), but I think an even bigger benefit comes from the dramatically increased comfort level in the home. You'll notice the difference as soon as you have the foil installed.
Q. We've got a vacation home close to the ocean, and we've been having continuous problems with our air conditioner ever since we bought the place. A repairman told me that saltwater corrosion can significantly cut the lifetime of a compressor and I wonder if you have heard of this happening before. It makes sense to me that it might, but I wonder there's really any truth to this. What do you think?
A. I think he's absolutely correct. Anyone living near a body of saltwater knows how everything from window sills to kitchen silverware corrodes quickly, so why would it be any different for an outdoor compressor? I've read some studies that note that beachside environments, especially when there is salt spray in the air, can quickly corrode the aluminum fins on the compressor and cut its expected lifetime in half. You'd help minimize the problem by rinsing off the outdoor coil surfaces every few months. You might also check with a building supply store for products they might carry that are specifically made for protecting coils.
I found an article on the Web that will give you some more information. Check out http://usacoil.com/NEWSLETTERS/mar2001.pdf for more information on this problem.
n
Ken Sheinkopf is a communications specialist with the American Solar Energy Society (www.ases.org). Send your energy questions to askken@ases.org..
(c) 2007 Virginian - Pilot. Provided by ProQuest Information and Learning. All rights Reserved.