How to Work Out the Running Costs of Electrical Appliances
Electrical appliances can use a large percentage of the electricity in the modern home, and you can estimate the costs of running the appliance with a few simple calculations. There are also devices which can monitor the actual usage of the appliance, including both the active and standby power. Many devices, even when switched off, go into a standby mode whereby some circuitry is active -- any device with a remote control, for example, will draw some standby power. For estimating purposes, however, the amount of standby energy usage is quite small compared to operating consumption. Does this Spark an idea?
Instructions
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Estimated Usage
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1
Contact your lower power utility and determine your cost for a kilowatt-hour (kWh) of electricity. The rate also can be determined from your latest utility bill or statement.
Most residential customers pay a constant rate for electricity, while commercial customers may have variable rates depending upon time of day and peak usage. Check with your utility for details.
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2
Examine the appliance you are interested in and determine its operating wattage. This is usually listed on the UL or operating label affixed to the appliance.
This wattage is an estimate, and can depend upon the exact use of the appliance. In general, it should be accurate to within 15 percent.
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3
Calculate the number of kilowatt hours this appliance will use in an hour of operation. For example, a hair dryer consumes 1,500 watts of electricity. This is the amount of electricity consumed every instant of operation. In one hour, the hair dryer will consume 1,500 watt-hours of power.
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4
Convert the power consumption calculated in Step 3 into kilowatt-hours. This conversion is performed by dividing watt-hours by 1,000. In the hair dryer example, 1,500 watt-hours of power divided by 1,000 means that the hair dryer consumes 1.5 kWh per hour of operation.
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5
Multiple the power consumption of the appliance by your utility's power rate. If your utility charges 10 cents per kWh, for example, multiply the hair dryer's 1.5kWh by 10 cents to discover that it costs about 15 cents per hour to operate the hair dryer.
Actual Power Consumption
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6
Procure a watt meter, a device which can measure the actual electricity consumed by an appliance. See the link under "Resources" for an example.
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7
Plug the watt meter into a wall socket, and then plug the appliance into the watt meter.
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8
Program the watt meter with your utility's cost of a kWh of electricity.
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9
Reset the watt meter and use the appliance normally. The watt meter will then show the actual cost of running the appliance.
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Tips & Warnings
The wattage listed on an appliance is the maximum power used by the device. The estimation method outlined above will not work for devices with multiple levels of consumption such as refrigerators, freezers, air conditioners and heaters. These devices may operate for long periods of time in reduced power consumption modes.
Large appliances, including refrigerators, heaters and air conditioners sold in the United States and many other countries are required to have labels indicating their estimated annual energy costs.
