The basic unit of electrical measurement is a watt. A fluorescent tube in an under-the-cabinet kitchen light fixture needs 8 watts of electricity. An incandescent bulb for a reading lamp needs 100 watts. A microwave oven needs 900 watts, a hair dryer 1,875 watts. Furnaces, air conditioners, dishwashers, and water heaters also need watts to operate.
Those watts add up rather quickly, so it’s easier to use the word kilowatt, a short way to say “one thousand watts.”
But a kilowatt only describes the amount of electrical energy needed to make devices do their work.
A different phrase describes what happens when these devices are working. The number of kilowatts must be multiplied by the number of minutes the device is turned on. The answer is expressed as kilowatt-hours. Using a 100-watt light bulb for 10 hours equals 1 kilowatt-hour.
As you switch devices on and off during the month, your electric meter keeps track of the total number of watts of electricity you use. This grand total shows up on your electric bill as kilowatt-hours.
If you want to reduce your energy expenses by lowering the number of kilowatt-hours on your monthly electric bill, you have two good choices.
You can substitute a lower watt device (such as a CFL or LED instead of an incandescent bulb) and use it for the same amount of time. Your total kilowatt-hours will be lower.
Or you can operate a device for fewer minutes (such as adjusting the thermostat on your furnace or air conditioner).
Your total kilowatt-hours will be lower.
Either way, you’ve used less electricity. Do both, and save even more.