Consumption challenge week one — Measuring electrical usage

Summer’s officially here! And so we’ve launched the project to reduce our electrical and water consumption.

This first week is all about electricity measurement, because it’s more difficult (and less fun) to reduce when you don’t know your starting point.

Objective number one: follow the money.

If you are challenging your consumption along with me, find your electricity bills for the last year. Use excel, google spreadsheets or pen and paper to create a chart like this one showing usage, kWh charge, and your total bill. If you are feeling ambitious you could add a column for the average temperature for each month. If you are feeling more ambitious you could turn the data into a chart.

I am fine with a simple table:


A few disclaimers here…

  • Unfortunately we didn’t move into this house until the middle of Sept. I called TXU and asked for the data of the previous tenant. They would provide approximatge kWh for those months but that was it.
  • Because we moved during Sept. that month is partial, and so I believe that figure is artificially low.
  • We were out of the country and pretty much not living in the house Nov.-Jan.
  • Because of all these factors, the standard error here is plus-or-minus a LOT, but it still offers a general trend.

What this exercise taught me (other than that I need a better organization system for old bills!) is the following:

  • A/C must be by far the largest portion of my electrical usage. Not a surprise. By extension it’s also the greatest opportunity for reduction in consumption.
  • Over the course of a year a rough average monthly kWh consumption rate for my house is 670/month.
  • Whatever billing plan I am on, the kWh charge fluctuated by a couple cents each month.
  • Based on the one month of overlapping data, I can assume that the cooler recent weather has had a direct effect on our electricity bill by reducing our use of the A/C.
  • The fridge must be using about 200 kWh / month by itself given that when we were not here, we still used this amount. At 15 cents/kWh that’s $30/month to keep the food cold. Not sure yet if that’s a lot or not compared to others, I will have to see.

So, given all this loose data, what will be my consumption challenge goal? I suppose it’s copping out to say awareness? Then I’ll say to save 10% over the same time last year, just for the sake of comparison. I’ll compare both consumption and total billing. How difficult this will be depends on things like weather and how our consumption pattern compares to the single retired lady who occupied this house before us. Did she keep the thermostat at 68 or 78? I guess I’ll find out.

To kick-start the savings we are setting the thermostat at 78 or higher. I read that for every single degree one adjusts the thermostat, one saves 10% on electrical billing. We shall see.


4 responses to “Consumption challenge week one — Measuring electrical usage

  1. I was listening to a podcast that describe some of the usage figures and it made me come back to this post. One of the things I picked up from it was how much the washer and dryer eat up. We wash quite a bit at our house but I guess we will have to slow down. Here is the link.

    itpc:// – The Greening of ‘White Goods’:
    Environmental Considerations When Specifying Appliances.

  2. Erin, I don’t think your refrigerator could be using that much electricity in a month. I found an old Energy Guide from a GE fridge I purchased in 1993 and the average yearly consumption for that model, a 21 cubic foot top mount freezer was 763 kw or about 64 kw a month. At 15 cents a kwh that would only amount to about $9.60/month.

  3. I’ve thought about it since that original posting and figured that my original monthly assumption for the refrigerator is probably high, but maybe not outrageous. The only other things going in my house at the time were a 60 watt light that would come on for about an hour a day, and the guy watching our house ran the dishwasher once a week.

    I looked and this fridge appears to have built in 1987. Probably not an energy efficient vintage. 😉

    The point I’m trying to make is that backing out of one’s bill the major components is a worthwhile exercise in knowing what sucks up the most energy. That awareness should make it easier to start consuming less because people presumably make better decisions.

    Here is an interesting report on refrigerators. Old, perhaps, but worth a look.

    “Kitchen and Laundry Appliances

    Kitchen and laundry appliances accounted for about one-third of household electricity consumption in 2001. Refrigerators, the biggest consumers among household appliances, used 156 billion kWh of electricity (Figure US-3). More electricity was used for refrigerators than for space heating, water heating, or lighting.

    Unit energy consumption (UEC) is a measure of electricity consumption per unit per year. For refrigerators in 2001, the average UEC was 1,239 kWh, while U.S. households on average consumed 1,462 kWh for refrigeration. The average for household consumption was higher than the average UEC due to an upward trend in the number of households with more than one refrigerator. In 1984, 12 percent of households had two or more refrigerators; by 2001, 17 percent (18.1 million households) did.”

    Thank you for commenting!

  4. Pingback: Consumption challenge update: Simple changes cut my water bill in half!!! « erin covert * hands on

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