"Off" is a Three-Letter Word by Michael Lamb

To accomplish my mission, I constructed a testing device to meter energy demand (see "Making a Phantom Meter"). With this device, I started my energy crusade. Table 1 shows the appliances I metered while they were off, their projected yearly energy use, and an estimated yearly cost of energy, assuming that the appliances are plugged in but never used. Any usage would obviously make the costs higher. I have not attempted to compensate the values on the list for power factor, so these results are not exact. They do, however, provide a ballpark range for the devices I tested.

Clearly, no single one of these loads will break the household piggy bank. However, if we consider that there are hundreds of millions of most of these devices around, the size and number of power plants needed to produce the power to do essentially nothing is staggering.

Take televisions, for example. My 27-inch TV has a phantom load of about 13 W. I actually do watch the TV some of the 24 hours per day that it is plugged in. So--departing from Table 1--let's subtract out some of the day as legitimate usefulness. Assuming that the TV is used 3 hours per day, six days per week (I don't watch TV on Saturdays), that's still 150 hours per week (21 x 6 + 24) that the TV sits doing absolutely nothing. Multiply the 13W phantom load by 150 hours per week by 52 weeks per year, and the result is about 100 kWh per year of off-time usage. At an electric rate of 8.5¢ per kWh, it costs me about $8.50 per year.

Not a great deal of money, admittedly. But let's assume that there are 10 million TVs similar to mine in the United States (according to the Energy Information Administration, 94 million U.S. households have TVs and 55 million of those have two or more.) At 100 kWh per year each, this adds up to about 1 billion kWh per year of wasted energy. This is about the same as the yearly usage of 167,000 all-electric houses (at 500 kWh per month per house). At 8.5¢ per kWh, that's about $85 million per year nationwide.

So why do TVs do this? My particular TV uses this energy to maintain its feeble memory of stations I don't wish to watch and to keep the receiver for the remote control ready to respond to my being a couch potato. In some older TVs, power is also used to keep the picture tube filaments warm for faster start-up.

One way to save this energy is to kill the power by means of a wall switch or by plugging the appliance into a power strip. Better still, the units could be manufactured so that the hot side of the power cord enters a real switch before it goes anywhere else in the unit. Of course, these solutions will cause the TV to "forget" which are the undesired stations and not respond to the commanding potato on the couch. To keep this from happening, a good electronics technician can add a battery backup with sufficient capacity to keep the memory intact for those "totally off" times. The battery can easily last at least several days per charge. Most video cassette recorders already have a battery back-up that lasts 20 minutes or so. Adding a bigger battery would not be difficult.

Another particularly vexing finding was that even the Energy Star computers I metered (both Dell and Gateway models) use a couple of watts even when they're off. This waste can again be avoided by killing the power via a wall switch, or the switch on the power strip or surge protector that most PC users already have. But there is really no reason why the units couldn't be manufactured so that the hot side of the power cord enters a real switch before it goes anywhere else in the computer or monitor.

Michael Lamb is an energy consultant in northern Virginia and is on the staff of the Energy Efficiency and Renewable Energy Clearinghouse.
 
 

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Meier, A., et al. "The Miscellaneous Electrical Energy Use in Homes." Energy: The International Journal Vol. 17, No. 5 (1992): 509-518.

Nakagami, et al. (1996). "Lifestyle and Energy" Tokyo: Jyukankyo Research Institute.

Nore, D. and M. Roberts. "Miscellaneous Residential Electrical End Uses: US Historical Growth and Regional Differences." ACEEE Summer Study on Energy Efficiency in Buildings, Vol. 7 (1994): 179-188.

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sidebar Making a Phantom Meter I began by constructing a simple shunt tester out of a 1,000 ohm, 10%, 7-watt resistor, duplex receptacle, and a few other electrical parts. I was concerned about two inherent inaccuracies of my testing system: the tolerance of the 1,000 ohm resistor and the accuracy of the digital multimeter. So I cross-checked my meter with other newer meters at an electronics store and found that mine was pretty close. I then checked the tolerance of the resistor in a more primitive way. I measured the resistor at room temperature (990 ohms) and then pumped about 14 watts (twice its rating) through it for 60 seconds. This caused the resistor to heat up and change value some. I then quickly measured its resistance again before it had a chance to cool off (1004 ohms). This simple test proved two things to me--I had a pretty good resistor (it changed less than 1.5% under abusive conditions); and when I am testing appliances that are "off" I should be well within the temperature tolerances of the resistor. The results achieved from the meter do not account for power factor, which means that it could overestimate actual wattage somewhat. However, the device is an inexpensive way to get a rough idea of the phantom power draw of different appliances. For detailed construction plans, send $1 and an SASE to Michael Lamb, 7920 Appomattox Ave., Manassus, VA 22111.

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