Energy Monitoring

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By Energy Circle Staff - December 18th, 2009

START HERE to learn about home energy monitors and home energy management systems: what they do, how they help, how to choose the right electricity monitor for you, and everything else you need to know to get started monitoring your energy and saving money.

Real time energy monitoring is an energy efficiency breakthrough.  Studies show (and we've proven in our own usage) that seeing electricity usage firsthand, in real time, leads to substantial reductions -- 15% savings on electricity bills is not uncommon.

This article is designed to (I) Introduce you to devices that monitor electricity, (II) Describe the types of electricity monitors that are available, (III) Help you figure out which monitor is the best bet to help you reduce your usage and save money, and (IV) address other Frequently Asked Questions about energy monitoring. If you still have questions, feel free to contact us. We're happy to help you get started. 

I. Why Do Monitors Help?

For most us, electricity is invisible, and utility bills are at best cryptic, and at worst complete mysteries. Energy monitors make electricity use tangible - rather like a thermometer makes the air temperature visible. And like a thermometer, a monitor does not reduce electricity use on its own - it simply prompts a response from you. If it's cold outside, you throw on gloves. If your monitor displays a spike in electricity use, you find out why and turn some energy hog in the house off.

What Energy Monitors do:

  • Help you locate things that are always on, even when they aren't doing anything. 
  • Help you notice that the kids forgot to turn off the TV. 
  • Help you become aware of how electricity is used. 

What Energy Monitors prompt us (homeowners) to do:

  1. Understand what goes on when we use electricity in our houses.
  2. Pay attention to our usage and reduce it. 

Studies show that people using electricity monitors will save between 5% and 20% on their bill. One Energy Circle staffer has reduced his electricity consumption by about half, saving around $100/month.

How much you save is a matter of how much you use now, and whether you pay attention to what the monitor tells you.  That's why it's key to find the monitor that meets your needs. 

II. What's the Difference Between Different Monitor Types?

Monitors come in four different categories, each of which we discuss in greater detail below:

  1. Measure Just One Appliance: "Plug In" type
  2. Measure the Whole House in the last minute or so: "Instant Readout" type
  3. Measure the Whole House at the Moment and Track History: "Readout + History" type
  4. Measure Circuit by Circuit of the Whole House at the Moment and Track History

1. Monitors that Measure Just One Appliance: Monitors that measure just one appliance (e.g. the Kill a Watt) isolate energy usage. You plug the appliance you want to measure into the "plug in" type meter, and then plug the meter into the wall.  We think this is a vital tool for understanding individual appliance draws. The best, most economical product for this is the Kill a Watt EZ electricity monitor.  In addition to the features of the basic Kill a Watt, the EZ model displays the cost of running whatever appliance you plug into it - by hour, day, week, month or year.

2. Monitors that Measure the Whole House in the last minute or so: A major step up from the single-appliance meters are monitors that measure the whole house.  Electricity usage monitors like the Blue Line PowerCost Monitor and Wattvision Power Monitor attach right onto your electric meter and instead of reading it monthly like your electric company, measure it every few seconds.  Other instant read monitors, such as The Owl, or The Owl Micro, and The Energy Detective (TED 5000) connect inside your electrical box and most send their readings to a table-top display.

3. Monitors that Measure the Whole House at the Moment and Track History:

A step up from the instant read monitors are monitors are that track usage over time.  Being able to track energy usage history - whether month-to-date or month-over-month - can be extremely useful in that it provides you with a benchmark (say, for example, "Let's try to do better this month than we did last month") as well as a means to assess your progress and make adjustments accordingly (for example: "We've used more in the first two weeks of this month than we did in the first two weeks of last month; let's try to really cut back in the next two weeks to make up the difference.") The TED 5000 series was the first to effectively do this trick, even allowing storage of your energy data on Google PowerMeter -- a free service that provides nice charts, evaluation, assessment and comparative data to help you truly understand your power usage.  The TED 5000 has proven to be tricky for many people, but other options are available since late 2010, including a WiFi connection that can be added to the BlueLine PowerCost Monitor, Wattvision, and CurrentCost Envi.

4. Monitors that Measure Circuit by Circuit of the Whole House at the Moment and Track History:

All of these levels of measuring your electricity consumption are like having increasingly detailed picture of how energy from electricity ebbs and flows.  But for a truly detailed picture, you can see your electrical use on a circuit-by-circuit basis, with a new, first-of-its-kind product called eMonitor, as well as a similar product by BrulTech.

A modern house typically has 20 or more separate electrical circuits, all leading back to the main breaker box where the electrical feed comes into you house.  Circuits feed the power to an individual room, and often for larger loads, a single appliance, such as a dishwasher, dryer, or refrigerator.  eMonitor provides all of the instant data collection and history, but is able to break readings down to individual circuits.  Power House Dynamics, the maker of eMonitor, describes their system as a tool for "electricity management", which is a step above monitoring.  The level of detail is really important -- we have heard reports from customers who say that they have found significant unneeded power users, and easily saved the cost of the product by being able to quickly isolate the source.

We think this real-time information is indispensable for understanding and reducing electricity consumption. You will know exactly how many kilowatts your house is using. The question is, what do you do with that information?

III. Which Monitor is Right For You?

Now you know about why each level of monitoring can provide further detail.  Which one is right for you?

If you live in a city apartment, or just want to know about how a few of the things you plug into the wall use electricity, the Kill-a-Watt is probably your best choice.  Simply plug it in between the fixture you want to measure, and plug the fixture into it.  It has an LCD display, so you can see right away how much power a single fixture uses.  Simple as pie.

If you live in a house, and want a super simple installation process, either the Blue Line PowerCost Monitor or Wattvision electricity monitor would be a great choice.  They both are designed to read most electrical meter in the US and Canada -- even the older models that have a spinning dial!  Installation is quick and easy  -- a screwdriver is all you need (to attach a special gizmo to the meter).  The BlueLine has a display that can be placed anywhere in the house, within 100 feet or so of the meter, depending on what's in between.  If you want some more details, we have a video explaining how to install the Blue Line PowerCost electricity monitor.

If you have a special requirements, such as solar a whole house electricity usage monitor connected to your electric box is the way to go. These monitors are installed in the electrical breaker-box (or even old fashioned fuse-box) serving your house.  While working in the electrical panel can be daunting, and you should check local regulations before doing it, it's actually a simple job.  Hire an electrician if you're at all uncomfortable, but it's a quick and easy task for anyone reasonably handy. The TED 1000 series has a nice display and does a good job.  The TED 5000 can handle sub-panels, an solar or wind inputs, and The Owl and Owl Micro are inexpensive and simple to install.

If you love data, want access to your historical use, and want Google PowerMeter integration, opt for Wattvision, eMonitor, TED 5000, and now even BlueLine's WiFi connection. eMonitor and TED will need a standard router and Ethernet cable to plug the device into.  Wattvision and BlueLine Wifi use wireless networking. Setup is usually straightforward -- you do it right through the same web browser you're reading this on!  

IV. Other Questions:

Do You Need A Display?  Data from Wattvision, TED 5000, BrulTech and eMonitor is available through a web interface on a computer or smart phone.  A wireless table-top display is standard Blue Line and The Owl, and is an optional item for the TED 5000 and Wattvision.  Having tested all these devices extensively at Energy Circle, we are advocates for having a display -- these monitors work to help you save by gently but constantly reminding you of how you are using electricity.  Sure, you can go to your computer (or iPhone or other web-enabled phone) and bring up some pretty cool readouts and details ... but having that little display in our hallway or kitchen is easy to read at a glance.  While you're the best judge of what will be most effective for you, we've found that a display sitting quietly on the kitchen counter is extremely useful. 

Multi-family Housing: If you rent part of your house to a tenant, you may only have one meter.  The units that install inside of electrical boxes can usually be configured to measure separate units, either for billing purposes, or just to provide tenants the information they need to reduce their electrical usage. 

Solar and Wind: If you have solar panels or a wind turbine producing power, both TED 5000 and eMonitor have optional versions providing "net metering" and can determine the amount of power being produced.

Non-standard Wiring: A strength of the meter-attached devices is that they can read a whole house with one device.  The monitors that install in the power panel, such as The Owl, TED 5000, eMonitor and BrulTech require additional parts for certain non-standard wiring, notably homes having multiple 200A 2-phase panels, or sub-panels.  But chances are you won't need this -- the majority of US and Canadian residences have "2 phase 240V service".  As long as you have a single electric meter, PowerCost monitor and Wattvision will work fine regardless of your wiring.  Bear in mind, none of these units are designed for non-residential buildings, which often have a different wiring scheme, and may have different local ordinances with regards to accessing the electrical panel or meter.

What About Gas or Oil Usage? Sorry, you're out of luck ... for now.  Given that in colder climates oil or natural gas can cost far more than electricity, we think there should be as much of an effort to have meters that also measure this important energy source as well. With luck, the designs of current models would allow them to accept this additional data once someone comes up with a clever way of reading it.  For now, read your bill.  We're doing our best to influence the industry on this score.

Cost: Various models have different costs -- the Owl Micro is currently in the lead at $79, and the BlueLine (no WiFi) is close behind at $99.  Generally, the greater the detail in information, the higher the cost.  Those providing whole house readings that transmit data to the Internet run about $250. eMonitor and fully configured BrulTech meter both will cost significantly more.  

But it is important to remember that if your electricity bill is $80/month (average for the US), and you can reduce only 20% of your electricity use, you'll save $140 per year.  You might break even the first year, but we're very confident that motivated homeowners can do far better than 20% -- and any savings you make pay back, year after year after year.  And don't forget, the money you don't spend is tax free!

Builders,  Remodelers, Contractors and Energy Auditors: Builders and remodelers should consider offering these products to customers -- there's probably a very short payback period for any monitor, and building green is a great selling point.  Email us directly if you're interested, as we're constantly hearing from customers who want us to connect them with people who know how to install them and set them up.  Home Performance pros using our Energy Circle PRO platform have access to the products in our store.


I'd like to reinforce your comment about the importance of developing monitors for natural gas. I live in the Chicago area and roughly 60% of my annual energy costs (and a large % of my household CO2 emissions) come from natural gas. While measuring my electricity usage is important and interesting, I'm much more interested in observing my total energy usage (gas + electricity) throughout the year. Please keep the pressure on the industry to address this! Posted by Anonymous on Jan 27, 2010 12:32pm
Onece again, you left out Brultech ECM-1240 which may have beaten the E-monitor as the first whole house circuit by circuit monitor. Additionally you can monitor gas or water usage (or any meter which sends a pulse) with the ECM-1240. Net metering is also supported for Solar & Wind installations. Geoff (I have no affiliation with Brultech other than owning one of their monitors) Posted by Geoff on Jun 10, 2010 9:45am

Hi Geoff --

Thanks for your comment.  This article was written last year, at which point we had no awareness of the BrulTech product.

However, as soon as we heard about the Brultech monitor last year, we contacted the manufacturer and arranged to get one so that we could evaluate its capabilities.  There was a long delay between when I had provided the necessary information about my home's circuits, and when the monitor arrived -- perhaps a result of the same issues that had created a rather long back-order situation with TED and eMonitor.  Nevertheless, a few weeks ago, I did get a package.

Since then, I have found it difficult to find time to install the product, and that has delayed my full evaluation.  Part of the issue is that the individual circuits are measured using solid-core CTs (rather than split CTs), meaning I'll need to pull each breaker, unwire, slip the CT over the hot lead, and then reassemble.  It's not particularly hard, but it means the power's off in our house for an hour or so.  This wasn't an issue for the 6 or so other monitors I have assesed.

That has created enough of an impediment that I have not yet found time to do it.  This is a lame excuse, to be sure, but if you have kids in school, you'll understand that at this time of year there appear to be something like 19 hours in a day, whereas there are demands for 27 hours.  I don't understand why, but it's always the same, every Spring :-)

As far as gas monitoring, I saw that there's an option for that, but do not believe I have the necessary hardware to make that a reality (although I think my gas meter is compatible).  It's certainly a good feature, as total home energy is our focus.

I can assure you we have no desire to leave BrulTech out of the mix -- it may be the right solution for a number of kinds of customers.  We will sell any monitor we can, as we believe all have merit.  The barriers to installation in existing construction do put the BrulTech at one end of the spectrum, a position formerly held by TED, which we think is great, even if, for a typical homeowner a little harder to install than we would like.  But other than some cosmetic concerns, I have no other basis to judge the product yet.


Posted by Tom Harrison on Jun 10, 2010 2:23pm
I have two of the Brultech devices monitoring my home panel. I had no problem installing the solid donut sensors. You only need to turn off the breaker you are installing the donut on and not the entire panel. These sensors installed rather easily with minimal disruption in household activity. I also have two of the Brultech split-core-60 sensors which I have connected to my A/C breaker. These two sensors look identical to the sensors used with the eMonitor. Although these are a bit easier to install, they are much larger than the micro sensors Brultech has. I can assure you that it would be impossible to fit one of these on each circuit in my panel due to space limitation. The example installation in your article appears to be done in a rather large modern panel. I am extremely happy with the Brultech's performance. Although I had to experience some software growing pains, it all has been working great. I can already see my payback in less than two years. Posted by Typical Home Owner on Jun 14, 2010 11:09am

So, um, "Typical Home Owner", correct me if I am wrong, but to install the un-split CT (donut), you need to remove the hot lead from the breaker, slip the CT over the lead, and reinstall the lead.  I would not recommend that any typical home owner (not you, an actual typical home owner) do this work without turning off the main breaker -- a metal screwdriver on the breaker lugs, an inch away on either side from hot circuits seems like a really, really bad idea to me.  Pulling the breaker is also possible, but again, you now have the panel's bus exposed.  Again, no big deal to turn off the power for a little while, I just haven't gotten to it.

So to be clear: Energy Circle recommends strongly that you turn off the main power to your house when you remove the cover of your breaker panel.  Some localities require a licensed electrician, and we recommend hiring one.

A quick correction -- the eMonitor comes with a set of (split) CTs for larger and smaller circuits; the CTs for larger circuits are still very small, the 150a CTs are larger, but intended for the mains only.  There's no doubt that there are a lot of wires running inside of the breaker panel when all is sad or done (true with Brultech, too) but there has been no one that has found this to be an issue.  My panel is, crammed with circuits -- in order to get additional circuits the electrician installed a number of half-height breakers so that two circuits can be installed in a single space.  But there's plenty of room (actualy, plenty of room for both, plus a TED, plus either an Envy or Cent-a-meter) :-)



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