by Ethan Johnson
June 29, 2008

[Updated 6/30/2008 - see end of article]

I have been engrossed in the pursuit of learning about energy production and consumption. And as I have mulled about these topics, I have been observing that a good percentage of the energy we US denizens consume seems to be based on the concept of "doing it because we can." Simply put, if you had to generate the necessary electricity to power all of your electric doo-dads "off the grid", you'd be a Luddite inside of a week.

Thanks to David Butcher's extensive writing on the subject, I have been exploring lots of avenues and learning not only about energy production and consumption in general, but our consumption as well. He suggests a simple experiment to determine what the "floor" of your electric usage is per month. The full instructions are available via the link I just provided, but here is the quick version:

• Turn off everything that isn't normally used during the day. Do not get rash and unplug the refrigerator or stove. Let the fridge run idly, let the microwave time keep displaying, and so on. I did take the step of turning off the A/C temporarily to determine our base consumption rate, as it does shut off from time to time. (In short, set up the house as if you were away on vacation, and let whatever items remain plugged in/powered on as you normally would under those circumstances.)
• Bring a stopwatch out to your electric meter (the box with the spinning disc in the center). I did this late at night when our electric usage is lowest.
• Time how long it takes the spinning disc to make one full revolution. There should be a mark in the center to aid with the timing. If the disc is spinning fast, make sure that you have turned everything "off" (within reason). If it's still spinning quickly, time how long it takes for the disc to make 10 revolutions.
• Look for a Kh number on the meter. Ours says 7.2 (that seems to be the going rate). Use this formula: ([Kh factor] * 3600) / [number of seconds for one revolution - if using 10 revs, divide that number by 10]
• This is your base consumption rate in watts. It's uphill from here.
• Check this at different times of the day to get a feel for your electricity usage.

Our formula result as of 11:55pm yesterday was:

(7.2 * 3600) / 33 = 785.45 watts

At one point during the testing, the A/C kicked on. I managed to get the disc to spin as slowly as 53 seconds per revolution, only to have the disc race around, prompting the 10 revs test. With the A/C running and the bare essentials in various states of operation, this kicked way up to 4890 watts. I assume this means 5 kilowatts per revolution (rounded up). 5 * 24 = 120 (1 day). 120 * 30 = 3600 (30 days). If our A/C ran 24/7 with the bare essentials running (this means no TV) then we could expect to pay about $530 USD per month for electric. That is, if I understand the above formula correctly and have calculated monthly usage accordingly.

Our most recent monthly electric bill says we used 1766 Kwh to the tune of roughly $250 USD. Yeah, doubling that would be about $500+ USD, so looks like my calculations are correct.

What this means to you:

• Try your darndest to run the A/C as little as possible. Here in Hell (North Dallas) we don't have that option, BUT, we have taken steps to help our crappy A/C unit run more efficiently. We installed solar shade screens on half of the windows (the sunny half), and have 2 attic turbine fans running (passively - they spin with the wind and the rising heat from the attic). During peak heat hours our A/C actually shuts off for long periods of time - as opposed to last year when it ran pretty much non-stop (hey! 3600 Kwh that month!).
• Unplug the non-essentials. Here is a great example: We have a digital alarm clock in the guest bedroom and no guests. Which means the time is being displayed to the furniture. Yoink. I can set the time when we need it for guests. I also had a power strip plugged in and turned on in another room with nothing plugged into it. Yoink.
• If you have essential electric items, consider improving its performance. If possible, upgrade to more energy-efficient hardware. Old fashioned filament bulbs are murder on your electric bill. If possible, switch to CFL bulbs (the corkscrew kind). Or better yet, LED lights. Better yet, use sunlight and turn the lamps off until absolutely necessary. If you leave your computer on 24/7 (we do, times two), turn off the monitor when not in use. We have LCD monitors so turning them off/on shouldn't be as traumatic as the older CRT models.
• Get the facts. Do the above wattage consumption testing to get a feel for your usage. Are you the dreaded Energy Hog? Or are you pretty low-key as electricity usage goes? Find out and adjust accordingly. Seriously, just because we have the ability to plug stuff in and leave it powered on for the convenience factor doesn't mean we should.

I will of course have more to say about energy consumption and production in future installments, but for now I think this is a good starting place for consideration of your "footprint". There are other areas of study, such as water usage, but start with base electricity usage. The results may shock you. (Haw haw.)

By the way, we're saddled with incredibly inefficient (proudly so, on the label) "big ticket" items, such as the A/C, furnace, and water heater. Our base rate won't go down to single digits, but whatever we can do to get closer to a livable number beats getting shellacked in August for $500+ for electric. If we can get down to the 2000s (Kwh) in August, I'll consider that to be something of a victory. <EM>

Update 6/30/2008: I got the house down to "nominal" energy consumption and took another meter reading. The meter disc was c-r-a-w-l-i-n-g, which is a good sign. It took 70 seconds for a single revolution, which translates as 370.29 watts, or .4 Kw/h. Assuming a constant consumption rate of .4 Kw/h for 30 days, we would use 288 Kw per month. Yeah, the A/C just kicked on so that's not going to happen. Anyway, good to know what our "floor" of energy usage is. Sadly, it's all uphill from there.

(More articles like this one may be found here.)