Five Percent: Conserve Energy

Climate Change Is Important: Energy Conservation is the First Step

October 14, 2009

Google PowerMeter Showed Me How and Why I Was Wrong

Category: Conservation,Household,Save Electricity – Tom Harrison – 10:11 pm

Google PowerMeter showed me I was wrong about something. Well, sort of.

Perhaps you have noticed: I am a little obsessive with my measurement of energy usage. Despite being an energy saving zealot, we still use our electric clothes dryer — perhaps as a rationalization, I had claimed that all those other people saying that we should use our dryer less had it all wrong. I said that this caused people to lose focus of the smaller items, especially the ones contributing to your “baseline” usage.

As I have pointed out, but said more nicely in a great article on PlotWatt’s blog, 100 watts, on all the time, costs about $100 per year for most people (more for us in the Northeast). Over the course of measuring electricity usage with several power monitors, I have reduced our baseline usage from about 700W to around 200W, which saves me a good deal more than $500/year in electricity bills. Finding the little energy vampires like my old Dell laptop which wouldn’t sleep on its own, to the old cable box (replaced with TiVo), to the 2 buttons on my “off” receiver, to the computer server in our hall closet — all eliminated, and all reduced our baseline. Success.

So was the dryer really that important? I have to say, it seems so now. Here is a series of screen captures from (actual) data from my TED 5000 now hooked up to Google PowerMeter, which I can see from my iGoogle home page.

What do you see?

Sunday — 13 kWh


Monday — 13 kWh


Tuesday — 12 kWh


Today — 20 kWh


So what happened today? The laundry. You can also see a similar spike on the first picture on the Saturday — 20 kWh. Guess what happened then? Yep, laundry. So if we keep this up, we’re using an extra 7 kWh on two laundry days a week. So about 13% of our current electrical usage is from the dryer.

On the bright side, our usage compares generally to a 2 bedroom apartment (we have a three bedroom house, 2 kids, the works).


  1. Thanks for the screenshots. Still trying to copy Google PowerMeter and TED roll my own solution. I’m tracking just current draw right now, so my numbers are in amp-hours, and I know that my readings are a little high when compared to the flashing IR LED on the meter outside, but if I estimate 120V that gets me to watt-hours. So far, it looks like I’m comparing favorably with your house. ;-)

    The units on these graphs are a little confusing to me (I could totally have it wrong). What are the bars in the graph showing? Average or max kW for that period, or the total kWh for that period? I don’t get the relationship between kilowatts used throughout the day and total kilowatt-hours used being presented here.

    Comment by blalor — October 15, 2009 @ 3:04 pm

  2. Yes, confusing. Watts are a measure of power; energy is power delivered over time. So a 100W light bulb on for an hour uses 100 watt-hours, for 10 hours uses 1000 watt hours, or 1 kWh. We pay our electric company for energy, so in kWh.

    But the graph is confusing indeed, as it says “electricity in kW”,
    but it’s really average kWh used over the period of the bar. Maybe not ideal, but I like what the display tells me.


    Comment by Tom Harrison — October 15, 2009 @ 6:06 pm

  3. Tom,

    That doesn’t seem right to me. Look at your graph labeled “Sunday” and focus on the 6 hour period from 12 am to 6 am when there is little going on but baseload. I count 24 bars in that 6 hours, one bar for each 15 minutes. If each bar is kWh, then your baseload is about 1/4 kWh (eyeballing the graph) per 15 minutes or 1 kWh per hour. That’s 24 kWh per day in baseload alone, yet the graph says you used only 13 kWh that day.

    On the other hand, if the y-axis is kW, as it is labeled, then your baseload is 1/4 kWh per hour or 6 kWh per day, much more in keeping with a total energy usage of 13 kWh.

    Comment by David Fay — October 15, 2009 @ 7:24 pm

  4. Tom – I’ve read all your posts and I’m still wondering if you have found a way to actively publish your TED 5000 data to the web (and not just using Google’s PowerMeter app).

    I have a TED 5000 as well and ran through a number of the problems you describe (and didn’t realize you were documenting ’til too late). But I would like friends to be able to see the actual footprints data not just a summary from Google’s PM app. I realize the 192. IP address returned from the router is a private address behind the firewall but do you know a way to publish the ongoing data on a site (and which doesn’t risk hacking intrusions)?

    Thanks, Chris

    Comment by Chris Hunt — October 19, 2009 @ 12:40 pm

  5. Chris –

    Here’s what I did to get my Footprints visible externally.

    First, a recent version of the TED firmware provides for basic authentication, for the display itself, or for the display and configuration (cool!). So turn that on.

    Then, configure your router so that it “port forwards” requests on a given port (http is usually 80, but I picked something different to be a little obtuse). You’ll have an option to send those requests to a specific IP address in your local network — the IP address of the TED.

    All done! Well, ok, now you need to test, so you need to know your home’s public IP address: easy, go to and it will display on the top.

    So if your public ip address is 232.141.456.29 and you set your port to 12345 you should be able to see your Footprints.html using the url http://232.141.456.29:12345/Footprints.html — depending on which options you selected for authentication, you may need to log in.

    Pretty easy if you’re comfortable doing the router setup.

    Have fun!


    Comment by Tom Harrison — October 19, 2009 @ 1:06 pm

  6. Thanks Tom, that worked and I can now get my stats out. Not ready for prime-time yet (and since it’s hosted on my home system the link is pretty slow) but it’s a start.

    I do have another question and that is, have you ever seen CTs that work with bus-bar setups? I tried hooking up a TED 5000 for a neighbor whose breaker box doesn’t have the mains coming in and out to clamp around, but instead has the bus-bar style of conduit mounted right on the wall. 3-4 wires come out of each conduit (4 conduits all together) once through the punch-out, but no way to clamp around the conduit as it now sits. The back of the CT would almost have to be flat. Seen any workaround for that?

    Thanks, Chris

    Comment by Chris Hunt — October 20, 2009 @ 3:37 pm

  7. Chris –

    I’m not familiar with this kind of wiring. Maybe the folks at Energy Inc. could help you out.



    Comment by Tom Harrison — October 20, 2009 @ 4:49 pm

  8. [...]  Then I got a TED 5000 about a year ago when it first became available.  I was amongst the first public users of Google PowerMeter and that provided more [...]

    Pingback by Energy Monitoring: It’s Not a Passive Thing | Tom Harrison Jr — September 14, 2010 @ 7:36 am

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