I’ve had a pretty set filing system for quite a few years. Bank statements, paid bills, and anything else more important than the average newspaper get filed in the appropriate slot in the cabinet. I’ve cleaned things out once or twice, but in general that just seems like more effort than its worth, so the folders have slowly gotten fatter over the years. This probably seems pretty dull thing to talk about, and it is, but it’s also what allowed me to go back over the four years of electric bills I’ve paid in my current apartment and analyze how much electricity I use. Each bill states the kilowatt-hours used in the previous month, so after ten minutes of leafing through them, I had all the data in a spreadsheet where I could take a look at it.

My yearly usage has been going up, but seems to be leveling off. There was a big jump from 2005 to 2006 and a smaller one from 2006 to 2007. 2008 isn’t complete, of course, but I’m on track for about the same amount as 2007, unless something unusual happens.

[caption id=”attachment_40” align=”aligncenter” width=”284” caption=”My yearly electricity usage, 2005 to 2008”][/caption]

Averaging out the data by month also leads to some insights. There seem to be two major seasonal effects at work. Running the AC in the summer has the biggest impact, causing spike in July and August. I also want to say that there’s a smaller bump in the winter due to the increased need for artificial light, but the data’s a little too uneven to say for sure. In particular, I’m not sure why it’s lower in September than in October, and why the trend is downward from October through December. Perhaps it’s because I’m often away for the last week or so of December.

[caption id=”attachment_42” align=”aligncenter” width=”463” caption=”My average electrical consumption, by month”][/caption]

The big picture is that I consume about 160 kWh per month, or 1,900 kWh per year. According to government statistics, the average household in Illinois consumes 770 kWh per month, and for the U.S. as a whole, that goes up to 920 kWh. I’m way below average, but I probably shouldn’t brag too much, since I have some built-in advantages which I can’t really take credit for. I don’t have to account for a washer, dryer, dishwasher, hot water, or heat. The only major appliances that show up on my electric bill are my refrigerator, my AC, and my 1400W espresso machine.

What could I do to get this figure lower? I’ve already replaced most of my bulbs with compact fluorescents. The only incandescents I still have either are used rarely, or are harder than the average bulb to replace (odd base sizes, on dimmer switches, or decorative bare bulbs).

My computer stays on (although asleep) all day. If I shut it off while I’m asleep or at work, I could probably save a few watts. Only a few though, since according to Apple in sleep mode it uses just over two watts, only slightly more than it uses when it’s off.

Addressing ”vampire power” (devices such as power adapters which consume energy even if they’re not being actively used) might save me a few more watts. I have a bunch of little electronic devices that don’t get used very often, but stay plugged in all the time. If I plugged these into a single power strip then I could turn them off when I wasn’t using them. Something like a Kill A Watt meter, or its DIY equivalent, would allow me to measure how much power is actually getting used by these devices. I’m going to think about this and see if it would be practical for me. If I have to dig around under my desk half a dozen times a day just to save a few watts, it’s not going to be worth the effort.