Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, November 12, 1995 TAG: 9511140058
SECTION: HOMES PAGE: B-1 EDITION: METRO
SOURCE: STEVE ELDER
DATELINE: LENGTH: Medium
Not all appliances are created equal. Some use a great deal more electricity than others because of design or function; some control systems work differently than others; and, finally, factors such as age and condition also come into play.
Fortunately, there are a few rules of thumb that are reliable: (1) the bigger the motor, the more it will cost to operate; (2) the longer the running time, the greater the cost; and, (3) anything that uses resistance heat will be expensive.
On rule No. 1, the operative word is ``motor.'' Don't confuse the size of the appliance with its operating cost. For example, a small circular saw can use over five times as much electricity as that huge wide-screen TV in the rec room. The physical size of the appliance is not always related to its power consumption.
To find out just how much money you're spending, look at the data plate on the motor of the appliance (almost all motors have a data plate). Find out the voltage rating (usually 120 volts) and the amp rating. For example, let's say your power drill uses four amps at 120 volts. Multiply 4 times 120 to get the number of watts, in this case 480 watts. Now look at your electric bill; you'll see that your utility company charges you by the kilowatt hour.
In the Roanoke area we're paying roughly 6 cents per kilowatt hour (``kilowatt'' means 1000 watts). This means that using 1000 watts for one hour costs 6 cents. Our 4-amp drill would then cost 480 divided by 1000, times 6 cents - or a little under 3 cents for one hour's usage.
By contrast, let's look at the average 100-watt light bulb. Since the rating is already in watts, all we need to do is divide 100 by 1000 and multiply by 6 to get an hourly cost of .6 cents. That's under a penny!
Now let's look at running time. Actually, this is a no-brainer; the longer you use something, the more it will cost. But let's combine this wisdom with what we've learned about motor ratings. Run outside and take a look at the data plate on your 20-year-old three-ton central air unit. You'll probably see an amp rating of 20-22 amps, but also a rating of 240 volts.
This ups the ante considerably. Using the same math, we get an hourly operating cost of 20 times 240, divided by 1000, times 6 cents, which comes to 29 cents. When it was 100 degrees outside this summer and that unit was running 24 hours a day, the daily cost was almost 7 dollars!
There are several lessons to be drawn from this: (1) don't yell at your mate for leaving the lights on when you've turned the thermostat down to 68, and the kids are leaving the door open; and (2) you might consider getting a new energy-efficient air conditioner that will cost a lot less to operate. (For homework, figure out how much money you'd save with a new unit that used only 13 amps over a cooling period of 400 hours.) Note that the other common 240-volt appliances in a home are the electric stove, water heater and clothes dryer - then consume accordingly.
Finally, any time electricity is run through a wire in order to heat the wire (``resistance'' heating), such as happens in a clothes dryer, a hand-held hair dryer, a toaster oven, a water heater, a clothes iron, a stove or a baseboard electric heater, you use a lot of electricity. This is why incandescent lights cost more to operate than florescent and why straight electric resistance heat costs more for your home than a heat pump. In physics electric resistance heat is 100 percent efficient, but it is usually not economically efficient. So, consider your options. Use a microwave to heat a cup of teawater instead of the stovetop; don't run the dryer for just one towel, fill it to capacity whenever feasible; teach housemates the virtue of shorter showers; turn the dishwasher's heated dry-cycle off. And now that you know how, calculate the operating cost of any new appliance or gizmo to see if your savings will actually amortize its cost.
It makes little sense to invest in a gimmick that takes 20 to pay for itself, but has a design life of only 10 years. (Unless, of course, it is a really neat gadget that makes you feel so good that you can skip a session with your psychiatrist!)
by CNB