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Green Architects' Lounge

Home Energy Monitoring, Part 2: Types of Monitoring Systems

In the Green Architects' Lounge, there's a discussion on the easy options available for homeowners to track energy consumption

The eMonitor. This circuit-by-circuit monitor has an Internet-accessible user interface and loads of information organized and customized to your tastes.

In Part 2 of this episode, Phil and I continue our conversation with Peter Troast of Energy Circle and delve into the different kinds of home energy monitoring systems available to the homeowner. From the Kill A Watt outlet monitor that you can rent from your public library, to the full circuit-by-circuit monitor you can access from your iPhone, we try to cover it all.

Types of monitors discussed in this part of the podcast:

  • The single outlet monitor, like the Kill A Watt
  • The whole house meter monitor—simple and succinct
  • CT (current transformer) monitors. You’ll have to open up your electrical panel for these—hire an electrician.
  • The circuit-by-circuit type, such as TED (The Energy Detective)
  • And of course, the monitors that grant you access via the Internet so that you can see what every circuit is up to from anywhere you can log on.

Enjoy the show.


Chris Briley: And we’re back. What are the types of monitoring systems we can choose from?

Peter Troast: There are a number of different things that define these consumer devices, but let’s be clear that the things we’re talking about display electricity use in real time, whether on a computer screen or a little device. You can walk past and see right now that the house is consuming 1200 watts. What distinguishes them is how they set up. I think what’s kind of a wrench that every house must have is the Kill A Watt. The Kill A Watt is a one-appliance-at-a-time measurement. It’s not real-time monitoring, and it doesn’t measure your whole house, but it’s just a really cool device that any appliance can plug into. That piece of toast—whoa!—that’s expensive.

Chris: A 1300-watt piece of toast!

Phil Kaplan: I know you can actually go to your public library now and borrow a Kill A Watt.

Chris: That’s great!

Peter: My daughter had a data collection project for school, and being the turbo geek I am, we decided to Kill A Watt every appliance in our home. Very time-consuming, but fun. At the end of the day, though, we could not make everything add up. Not everything has a plug, phantom loads, etc. So there are some limitations. That’s when you want to step up to the next level of device, which reads the whole house’s electricity use. What distinguishes these is where they collect the data. One user-friendly approach is a type that straps onto the electric meter externally. Now, depending on what type of meter you have—we have the old-school type with the wheel going round and round…

Phil: Sometimes when you see those things, you feel like you’re stepping back in time. It’s like seeing an 8-track.

Chris: Dude, I have a dial phone in my house. When I bought the house we’re in now, there was an old Ma Bell phone in its box, pristine condition, so we showed the kids, and they’re like—how do you work this? Now they think it’s fantastic, and it’s the phone they want to use. Now, what were we talking about?

Peter: So, that’s one type of installation, and it’s easy because it has nothing to do with your electrical panel. There’s no fear of electricity—just strap it onto the meter and watch the display.

Chris: So, there’s one number and you just watch the display?

Peter: It’s one number—what you’re using now. And you can plug in your electric rate so you can see that number either in kilowatt-hours or in cost…

Chris: And maybe use tracking software—

Peter: Well, that’s a distinction. In this category, there are two products on the market. One is the Blue Line. It’s a cool device, and just last week came out with a Wi-Fi add-on. The Blue Line is 100 bucks or less…

Phil: How much is the Kill A Watt by comparison?

Peter: There are two flavors of Kill A Watt—40 bucks and 30 bucks—depending on how sophisticated they are. So, the Blue Line at less than 100 bucks—easy to strap on, one device that’s wireless and sits wherever you feel like putting it and shows you what’s going on there. Not a lot of data collection. That’s my beef with the product. No graphing, so it’s hard to access the data over time. But it’s a nice price point. It’s easy to justify the cost; you’ll see the savings in less than a year.

The next category involves going into your electrical panel and clipping a CT—a current transformer—around the power lines, which reads the electricity moving through the wires.

Chris: Is that super accurate?

Peter: Yeah, it’s accurate enough. Most of these are power factor corrected, so it’s pretty close.

Phil: Those are real time whereas the ones clipped to the meter have some delay—is that true?

Peter: I would call all these real time. There’s a little delay with those clipped to the meter, but you’re pretty much in real time. Go turn on the 100-watt halogen can lights in the kitchen and watch the thing—cha-ching!—just go up.

Phil: You can see that happen as you flip the switch…

Chris: And think maybe I should have considered compact fluorescents or LEDs…

Peter: Yeah, yeah.

Chris: Maybe that architect was right. Maybe I should have listened to him. I don’t know; I’m just spit-balling.

Peter: We have nine cans in our kitchen. Some of them were swapped out for LEDs and some for CFLs, and I’m not sure why, but we still have three halogens—maybe for demonstration purposes. We now know that those three halogens, at 300+ watts, are really quite amazing.

So, the monitors that clip in—I officially need to say—should be installed by an electrician. It’s not that hard.

Chris: It’s not hard for them!

Peter: An electrician can do the setup in 10 minutes. It does involve taking the face off the panel, which is an intimidating thing, but the truth is these clips—the C-clamps just go around the wires. There are some videos on Energy Circle…

Phil: And they’re all licensed electricians doing it.

Peter: Of course. The videos show how to do this. Now, these devices read the whole house. The primary products include The Energy Detective—TED. The TED 1000 is 129 bucks. It has a nice little device that sits in the kitchen where you walk by all the time…

Chris: And it says, “What are you doing, Dave?”

So, there’s the kind on your meter, the kind with clip-in leads in the panel…

Peter: The next step is connection to the Internet. What distinguishes this step in the process, as you try to figure out what’s right for you, is how much do you love the data? I personally do. I’m a visual person. While it’s helpful to see one number at a time, it’s great to look at a graph or see that curve, and look at what happens when you turn the 6000-watt dryer on and your electricity use just spikes. When you first start, you get excited by the big spikes. Oh look, the toaster! Well, you make three pieces of toast a week—even though it’s 1300 watts, so what? But it’s really the base load that’s on all the time—in my house, it was 400 watts. A lot of it was phantom or vampire power of electronic devices. The big culprit for use was the entertainment center. The cable box is terrible—they use as much electricity when they’re idle as when they’re on. It’s appalling.

Chris: I heard there was legislation that said every device must have an actual off switch. Get rid of the obligatory clock. In my kitchen, the coffee machine has a clock, the oven has a clock, the kitchen has a clock. How dumb is this? I don’t even care what time it is when I’m in the kitchen!

Peter: It’s a really important subject. Some vampires are worse than others. The problem with the cable box is that it needs to be on—we record The Daily Show long after we’ve gone to sleep. We have an Apple TV—the great mystery is why in Apple’s great environmental reporting, the only device they don’t report information on is the Apple TV.

What we did to solve the entertainment center is use a smart strip. We designated a control unit—the TV. One plug is always on to keep the cable box on, but everything else in the center is dependent on the TV. With the smart strip, when the TV is not on, everything else is off too—100 percent off—with the exception of the cable box. That’s almost 200 watts. The cable box is 23 watts all the time, which is sort of maddening.

Chris: So, with the Internet device, I can log in from work and see if the kids left something on?

Peter: You can. The TED products are integrated with Google PowerMeter. This widget can be connected to the TED so you can see the electricity use wherever you are.

Phil: I have a TED 5000 that I bought from Peter at Energy Circle less than a year ago—

Peter: You didn’t buy it. Your wife bought it for you as a Christmas present.

Phil: Talk about geek!

Chris: She’s like, why did I marry this dweeb?

Phil: I love it; it’s on my iGoogle page.

Peter: Google PowerMeter is a great display, but it’s a pretty basic display. You also get the TED display, which has a lot more history and a lot more views.

Chris: Can the TED monitor specific devices? Can I partition the house so there’s not just one number for my overall usage?

Peter: The family of products we’re talking about now is just whole house. They’re 200 to 250 bucks. There’s promise that they will have external devices that you can associate with a specific appliance and then break out the use of that appliance—but only up to four.

The next tier is circuit-by-circuit monitoring. The cool device in this category is the eMonitor. I love it. My house has the eMonitor, the TED 5000 and the Blue Line. The eMonitor measures on an individual circuit how much electricity the TED uses!

Chris: Now we’ve gone down a deep geek hole!

Peter: I do think this concept of circuit by circuit is an important distinction. If you’re a little forensic and like sleuthing, with a whole house device, you can run around and hit switches and really dissect—OK, that’s the dryer, that’s the toaster, and so forth—if you have a simple house. That takes a little bit more doing. The beauty of the circuit-by-circuit piece is it’s all there. You can see the dryer on its own circuit, the dryer, the kids’ rooms…

This product sells—depending on how many circuits, 12 up to 44—for about $950 for a 24-channel version. That includes two years of service—a fantastic Web interface, but it also looks at patterns of data around the refrigerator, for example. Are the coils dirty or is the defrost cycle out of whack?

Phil: Are there other products besides the eMonitor that do it circuit by circuit?

Peter: There are a few others that we’ve tested but haven’t been satisfied with. There’s a high-end product called the Agilewaves—a factor of 10 more expensive than the eMonitor—but I was not able to see a difference in the display.

A lot of these devices will do a calculation of cost—even if you’re in a place that has complex electricity rates, in tiers and so forth, you can include that data and see exactly what’s going on. You get cost, electricity use, and carbon footprint.

Chris: Let’s break, and then come back to talk about cost.


  1. GBA Editor
    Rob Wotzak | | #1

    Other web-based monitors?
    Have you taken a look at the Web Energy Logger (WEL)? There's a case study on GBA of a house with one of these devices, and the builder seemed to be happy with it. WEL has a cool map that shows real-time tracking for many of the homes that have their devices installed.

  2. greenophilic | | #2

    Other monitoring options and perspectives
    First of all, good dialogue. I am glad anytime that energy monitoring is endorsed and educational efforts are undertaken. I would like to offer some other thoughts and suggestions.

    First off, other monitoring options. Brultech Research offers an electricity monitoring option that is fairly impressive and very affordable, considering its capabilities. These units have 7 data channels, which allows for a good bit of sub-metering of individual circuits. Also, the CT's that are used in this system for the individual circuits are very small (the size of a quarter or less). The typical operable CT is quite large (~3" in diameter), and attaching any number of these devices to the individual leads in a crowded panel can be very challenging. The downside of the small CTs is that the lead must be disconnected from the circuit to install. Communication options vary from wired to wireless, web-based or local CPU based. Another benefit is that these units have pulse-counting options, which means they can be connected to other devices with pulse outputs, such as gas and water meters.

    This last benefit brings up the biggest problem with the discussion posted here. Most homes use dramatically more energy for heating, both space and hot water, than they do for plug, lighting and other loads. With the exception of all electric homes, the electricity monitor doesn't tell you anything about the most important energy use in the home. This is problematic. Gas submeters can be installed by any plumber, just as TED and other electricity meters require an electrician. Examples of good gas submeters include the AMCO G4 200, the Norgas Gallus 2000, and the Sensus Cubix 250. Similar options exist for water sub-metering.

    Other electricity options include JetLun, WattsUp, and Wattnode. Onset computer corporation also has numerous energy monitoring devices, and all equipment that anyone could ask for to measure/assess home performance (including the infamous HOBO). These more advanced options are not appropriate for every home, but they offer impressive flexibility for those interested in more granular information. Cheers.

  3. Christopher Briley | | #3

    Thanks Brennan
    Great comment Brannan. Thanks for improving on the blog. (I'll have to look up Brultech)

    We echo your sentiments about "Energy" monitors, as they really are Electricity monitors, and by themselves can't give a total picture for a home that is burning oil or gas.


  4. user-940601 | | #4

    Where is part 3?
    Where is part 3?

  5. Christopher Briley | | #5

    Part Three on the way...
    My apologies. Due to technical difficulties on my end (The death of my computer) (not the fault of the GBA) the third part was been unexpectedly delayed.

    But now it has been published: Click here for Part 3.


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