September 22, 2023

My First Four Months With an Energy Monitor


I’ve been testing Powerhouse Dynamics’ eMonitor energy monitoring system for a few months now. And since living with an energy monitor is a new thing, I have periodically recorded my thoughts about it. Some of this has also appeared in a review in the October 2010 issue of Electronic House.

If you’re unfamiliar with the eMonitor, it is a circuit-level electricity monitor that can also monitor solar production-though I don’t yet have a PV system, so that’s not included here. The system costs about $700 for 24-circuit homekit smart plug  monitoring and a two-year subscription of $249. The interface appears over a web-based computer interface and a new iphone app.

This should give you a good indication of how one household has used his eMonitor for about four months now, through hot weather and now cold.

Set up

The eMonitor arrived on time. I took it out of the box and possibly for the first time ever, I read the entire user manual. Then i called my electrician, because installing it requires removing the front panel of our electrical panel, and that’s where an amateur like me stops.

My electrician has never seen an energy monitor system before, but he seems to know what to do. He removes the front panel of the electrical service and gets to work.

The eMonitor measures electricity usage via current transformers (CTs) that clamp around the two electric “mains” and up to 24 circuit wires. These sensors measure the electromagnetic field created by electricity use, and are fairly accurate. The CTs connect to a processor mounted near your main circuit panel and then attach via Ethernet to a network router and home network. That enables Powerhouse Dynamics to see the measurements and include them in the computer interface.

But first the CTs. The electrician placed the doughnut-shaped clamps loosely around the mains and the circuits. Dang, I thought. I could have done that! The wires from the CTs must go into the brick-size eMonitor processor that is mounted near the electrical panel. And while the electrician does this, he fills out a form so we know which circuits are on which ports of the eMonitor processor-as well as their amperage. Later, I input this information into the web-based registration and set-up portal so Powerhouse Dynamics knows what circuits are what.

The electrician would have liked numbers on each CT for easier marking, and a processor capable of handling more circuits. (I had to leave out two bedrooms, and my house isn’t quite 3, 000 square feet. )

The electrician’s work took about an hour or so, and my work at the registration site about the same. But I expected it to be far more complicated. The only hitches were figuring what times to input, to receive alerts if things like the well pump, boiler, and fridges are on for too long or not at all. The alerts are a big part of the eMonitor’s appeal. And I am pleasantly surprised that we’re soon up and running. Then i just needed some results, and that doesn’t take long. After all, I’ve got a teen and a tween. Those dudes are always leaving stuff on!

Day one (and a half)

The web-based interface is cool and intuitive-as well as colorful. The front page of the secure site shows my home’s current electricity usage in watts (updated every minute), the circuits and appliances currently drawing the most power, the top energy users in our house over the last few days, our monthly electricity costs to date (you input your utility’s rates during the registration), and a pie chart representation of our top electricity users. There’s also a carbon footprint comparison-ours is still smaller than our state’s average-heh, heh-and a graph of our electricity consumption over the past two days.

You can dig deeper and see a color-coded graph of hour-by-hour or minute-by-minute usage of all your circuits, which are color-coded. You can even highlight a section to get more granular. I love this feature.

You can also go to a Circuits page to examine individual circuits as well, and some of these come with energy-saving suggestions, such as reminders to clean the lint filter in our electric dryer.