A TED report on Earth Day

Last weekend while Benjamin was working, I decided to determine two things:

  • our electricity usage baseline
  • which devices contributed to that baseline and by how much

Like any performance analysis you need to start with a baseline: where are we now. I wanted to see how much electricity in kW our house was using with everything turned off. Of course “everything” isn’t, well, everything — it’s everything you decide to have explicit control over. For instance – while I’m all about reducing our electricity usage, I’m not going to go around unplugging our microwave, oven, washing machine, and alarm clocks at every turn. All of these devices use some amount of electricity to display clocks or respond to the ‘on’ button.

So with every reasonable thing unplugged or turned off on a beautiful Saturday afternoon, I loaded up my good friend TED and observed that we use ~0.168 kW. I then went through the house with my Kill-a-Watt to find out which of those always-plugged-in devices were using power and how much. Here’s what I found:

  • UPS = 34 watts
  • 3 alarm clocks @ 5 watts = 15 watts
  • 1 microwave = 7 watts
  • 1 wireless router = 5 watts

That only accounts for 61 watts, or 36% of our baseline. There are several other devices which I know use some power but I didn’t get to measure yet due to it being a pain to get to them:

  • cable modem (always on)
  • 5-port hub (always on)
  • oven (has digital clock)
  • washing machine (non-physical switch)
  • dryer (non-physical switch)
  • hot water heater (gas unit but plugs into wall too)
  • garage door opener
  • radon mitigation attic fan (always on)

Sadly, the UPS does not have a physical switch so even after turning it off the only way to stop it drawing power is to unplug it and it’s simply not worth the effort to me at this point.

Our current electric rate is $0.11883 per kW, so the smallest our electric bill could possibly be (excluding service fees and taxes) is $14.37 (0.168 kWh * 24 hours per day = 4.032 kW per day * 0.11883 = $0.47 per day * 30 days per month = $14.37 per month). Granted, we have to actually live in the house, so it will never be that low, but that give me our lower bound.

During the past few weeks I discovered some other interesting datapoints:

  • My computer, which is on at least 9 hours every day, only uses around 30 watts.
  • Benjamin’s hair dryer uses ~1 kW – which explains why the time he gets ready for work is often our peak kW usage during the day unless we turn on the oven…
  • The oven uses ~3 kW.
  • The clothes dryer uses ~3 kW off and on throughout its cycle and drops down to ~1 kW at other times. That’s unsurprising once you think about it – you’re not baking your clothes, you’re introducing hot air, tossing the clothes around a bit, and then more hot air.
  • The iPhone charger, as well as most other wall-worts, don’t actually use electricity unless they are being used. I was under the incorrect impression that these AC/DC converters would use some small amount of electricity while plugged in but not being used.

It’ll be very interesting to see how the electricity usage changes this summer when our AC kicks in.

Published by

cpeel

I'm a gay geek techie space nerd living in Seattle, WA.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s