What is The Watt?

(With apologies to Dave Eggers...)

Since going live with the Energy Circle house's electricity usage, we've gotten some questions from readers regarding what, exactly, that blue line represents: kilowatts? Kilowatt-hours? Electricity is a complicated monster but the kilowatt/kilowatt-hour question is pretty simple, so we thought we'd diffuse it for you.  Possible analogies are multitudinous, but we've settled on cars because it's a beautiful day.

A kilowatt is a thousand watts.  A watt is a measurement of power, and it's used to measure the rate at which an appliance consumes electricity.  Like miles per hour, it represents energy per second.

A kilowatt-hour is a measurement of energy, and it's the unit that a utility company uses to charge for electricity.  Think of it as the total distance driven.

So let's make a hypothetical situation, and say you're on a road where the "road company" makes you pay per mile traveled.  It doesn't matter how fast you drive, or how long you're on the road - it's just distance.  It's in a sense like a utility company, which doesn't charge for watts (the rate at which your house uses electricity), but for kilowatt-hours (distance driven).  How you determine kilowatt-hours is by multiplying the number of kilowatts your house is using by the amount of time it's using them.  Say, then, you're running an appliance that uses 1,000 watts, or 1 kilowatt.  If you run it for an hour, you've used one kilowatt-hour, and that's what you'll have to pay for (10-15 cents in most parts of the country).

So say you're running something like a toaster, which would use about a kilowatt.  If you only run it for five minutes, it's still using electricity at a high rate.  Think of it like driving 100 miles per hour for five minutes: you can cover some serious ground. Just for comparison, a CFL in a table lamp might use 15 watts (which we can think of as driving 1.5 miles an hour).  Running the toaster for five minutes would use about the same amount of power as running that CFL bulb for about 5 1/2 hours.

Now, how do you save money on electricity?  Slow down or stay off the road: use fewer watts, and use them for less time.  Driving around at 100 miles per hour is dangerous for you and everyone else.

Oh, and in case you were wondering, a Kill-a-Watt is a single-appliance electricity monitor.  We sell it and it's great.  Think of it as a plug-in speedometer for your appliances.