The Energy Column - Appliance Efficiency

The Energy Column 2002
Now in its 16^th year!
Written by: Ken Sheinkopf
Date: February 16, 2002 Column No.: 02-07
Phone: 321-638-1007
Fax: 321-638-1010
E-mail: sheinkopf@fsec.ucf.edu

Q.: "You just gave some really lousy advice to someone who wrote about turning off his water heater while gone from home for a few months. The simple answer is to turn the thing off, not monkey around with timers or whatever. I would just flip the house’s main breaker off and go away. How come you didn’t say that?"

A.: Wow. Don’t get so upset. I asked some water heating experts about your comments and they agree that while you’ve got some good points, you raise some areas of concern that they just don’t agree with.

First of all, if you’re going to turn things off in the house when you’re gone for a while, maybe the first thing to do is turn off the water. You don’t mention that, but a pipe leak within the wall could make a pretty good mess while someone was gone for a few months. That’s why it’s always good to have someone check on your house occasionally while you are away.

Second, the problem with flipping off the main breaker is that this cuts all power to the house. Energy experts usually recommend that you leave the power on and set the air conditioner to around 80 or 82 or so to keep humidity from harming the furniture and forming mold and mildew. A house that is totally shut and without power is a great breeding ground for mildew and other environmental problems.

Finally, you didn’t like my thought that flipping a circuit breaker off and on once or twice a year could put a strain on the breaker. You’re probably right that this is minimal abuse of the breaker, but I wonder what an electrical building official would say about this. I thought a breaker was designed for safety purposes. Sure, some people use the breaker to cut off power, but that’s not really its purpose.

Tell you what I’ll do. Let me ask readers out there to send me information on what they do when they go away from home for a few months or longer. I’ll bet we get a lot of good tips on what works and what doesn’t, and I’ll publish some of them in a future column. I’m sure there is a point somewhere between worrying about all the things that can go wrong while you are gone and some simple steps that can be taken to minimize most of these problems. Also, if any of you are electricians, building inspectors or home builders, let me know what advice you give to people regarding this concern.

Q.: "I hard that there is somewhat of a controversy between opening up attics to allow a lot of ventilation and closing the attic tightly with insulation. I can see where there might be merits to both of these strategies. You know anything about this?"

A.: I recently read a report on this very situation. Researchers at the Florida Solar Energy Center have been involved in a study that is looking at various building strategies, and we recently got some pretty strong information on the best way to go.

In a study of homes in southwest Florida that are about nine months old, one of the researchers examined the roofing systems primarily to observe some of the problems noted in the roof of the unvented insulated roof deck that he first saw in the summer.

There was clear evidence of problems with the shingles on the home that had an insulated roof that were not seen on the roof of the home with the ventilated attic, even though both homes had the same shingles. The sealed attic home had clear evidence of "buckling" where the shingles bent upward in the middle, forming a peak. This problem is usually caused by improperly applied felt or by movement in the plywood roof deck. Movement was suspected here since the roof deck in the sealed attic home experienced measured temperatures 20 degrees F higher each sunny summer day than did the house with attic ventilation. The researchers suspect that the larger change in the cycle of daily decking temperatures likely resulted in the buckling.

The home with good attic ventilation had no buckling, and all the shingles were lying uniformly flat.

As further proof of the temperature difference, the researcher actually burned his skin while lying on the roof of the sealed home taking pictures of the shingles. He didn’t have this problem on the ventilated home.

This seems to clearly support the notion that good roof ventilation is essential in keeping attic temperatures low and in keeping heat away from the living area of the home. It also shows that shingles on homes with ventilated attics ought to last longer and perform better.

Energy Note: Think people aren’t interested in energy efficiency? Portland (Oregon) General Electric recently gave away $6-off coupons to shoppers in Home Depot stores. More than 249,000 coupons were redeemed in one weekend. It was estimated that the sold bulbs would save about 19 million kilowatt hours each year, enough energy to meet the needs of 100,000 people for more than three weeks.