Earthanet

Want to know how much electricity you use? Your electric bill should give you a month-by-month breakdown by kilowatt hour for the current month plus previous year. Here’s mine, courtesy of Consumers Energy:

January 2008 Energy Use: 507KWH (total electric bill $51.25)

Dec 07: 409KWH, Nov 07: 467KWH, Oct 07: 381KWH, Sept 07: 415KWH,

Aug 07: 439KWH, July 07: 518KWH, June07: 507KWH, May 07: 420KWH

Apr 07: 404KWH, Mar 07: 156KWH, Feb 07: 258KWH, Jan 07: 293KWH

My electricity consumption of 507 KWH last month isn’t bad compared to the national average,which is about 1,134 KWH per month according to the 2001 US Department of Energy survey (the latest numbers we have). Of course, my household is smaller than the national average too. And I don’t like the fact that my usage is 73 percent higher on this month’s bill than last January’s 293 KWH. In fact, my usage this month was the same as last July, when I was running a medium size room air conditioner from time to time. What gives?

Look below the fold for the basic math and the online calculator I used to find out.

First let’s define KWH, or “kilowatt-hour.” Watts and kilowatts are the units your utility uses to measure electricity. Typically, anything in your home that runs on electricity is rated by the number of watts it burns in one hour of use. A 60-watt light bulb burns 60 watts of electricity every hour it’s on. If I leave it on for five hours, it burns 300 watts (60 watts x 5 hours=300 watts).

One kilowatt equals 1,000 watts, so a kilowatt-hour is an electrical consumption of 1,000 watts over a period of 1 hour. Unless you’re an electrical engineer, that’s probably confusing, so try thinking of your electric meter as a clock that runs faster when you use more electricity, and slower when you use less. Your utility’s billing department counts how many times the clock’s hands go around and sends you a bill based on the total, measured in KWH.

Next, let’s plug into this energy usage calculator which figures out how much each appliance in your household uses.

In the first field, fill in your month’s total electric bill (mine is $51.25)
In the second field, fill in your month’s KWH used (mine is 507)
In the third field, enter the wattage rating of the electrical appliance (60W light bulb)
Skip the fourth and fifth field for now.
In the sixth field, estimate how many hours a day the appliance is on (I estimated 5 hours)
Hit “calculate.”
The calculator will use the first two numbers to calculate your cost per KWH–my utility charges me 10.1 cents per KWH. The results you see above are the impact on my electric bill of a 60-watt light bulb that stays on 5 hours a day. 92 cents a month tells me the short winter days and the need for more indoor lighting isn’t the problem with my bill.

While I was figuring this out, the light bulb went on (so to speak), and I went downstairs to look at my dehumidifier. I have office space in my basement, and I like to keep things nice and dry, but in previous years the dehumidifier stayed off on its normal setting during the winter months. This year it’s stayed on all the time. I looked on the back of the appliance (which is basically a mini-refrigerator with condenser coils and an electric motor), but it isn’t rated in watts. It does have an amp rating, though–4 amps.

This time, since I didn’t have a wattage rating for the dehumidifier, I skipped the third field and for the fourth field I entered the household current standard 110 volts (always do this if you’re calculating based on amps–for a 220 volt appliance such as an electric dryer or electric range enter 220 in the fourth field intead of 110). Then I entered the dehumidifier’s amp rating of 4 in the fifth field. I entered 24 in the sixth field because it’s been staying on 24/7.

I hit “calculate,” and voila, the culprit–a whopping $32.45 a month. I went back downstairs and looked at the setting I had left the dehumidifier on, and it was way higher than what I was using last winter–I was hasty the last time I set the dial. Nothing like throwing money away—and that’s not to mention the greenhouse gases I’ve been responsible for.

In this case, the drain should have been obvious to me, but now I’m interested in tracking down other energy wasters in my household that might not be so obvious. My carbon clown shoes just got a size smaller, and I’m going to make them smaller yet, with the goal of reducing my winter electricity bill to under $15 a month.