We are a very technological society. Our electronic use rate is one of the highest in the world. However, we are aware that electronics use lots of energy. Fortunately, our technology has allowed us to be innovative and invent new devices that work very well and use less energy.
If you’re trying to decide whether to invest in a more energy-efficient appliance or you’d like to determine your electricity loads, you may want to estimate appliance energy consumption. The Department of Energy has created a formula to figure this out:
- (Wattage × Hours Used Per Day ÷ 1000 = Daily Kilowatt-hour (kWh) consumption) (1 kilowatt (kW) = 1,000 Watts)
- Multiply this by the number of days you plan to use the appliance during the year for the annual consumption.
- You can then calculate the annual cost to run an appliance by multiplying the kWh per year by your local utility’s rate per kWh consumed.
You can usually find the wattage of most appliances stamped on the bottom or back of the appliance, or on its nameplate. The wattage listed is the maximum power drawn by the appliance. Since many appliances have a range of settings, the actual amount of power consumed depends on the setting used at any one time.
If the wattage is not listed on the appliance, you can still estimate it by finding the current draw (in amperes) and multiplying that by the voltage used by the appliance. Most appliances in the United States use 120 volts. If not, find a clamp on ammeter, (an electrician’s tool that clamps around one of the two wires on the appliance) to measure the current flowing through it. You can obtain this type of tool in stores that sell electrical and electronic equipment. Take a reading while the device is running. This is the actual amount of current being used at that instant. When measuring the current drawn by a motor, the meter will show about three times more current in the first second of the motor running than when it is running smoothly.
Many appliances continue to draw a small amount of power when they are switched “off.” These “phantom loads” occur in most appliances that use electricity. Most phantom loads will increase the appliance’s energy consumption a few watt-hours. These loads can be avoided by unplugging the appliance or using a power strip and using the switch on the power strip to cut all power to the appliance.
Also, try to use ENERGY STAR labeled equipment. They provide users with dramatic savings, as much as 90% savings for some, with about half the electricity of standard equipment. Along with saving energy directly, this equipment can reduce air-conditioning loads, noise from fans and transformers, and electromagnetic field emissions from monitors. The ENERGY STAR website has a large database on all the various kinds of electronics.