Just ordered a small energy monitor for the main condo panel. Call it 40% professional interest, 30% desire to be more energy efficient / save money, and 30% number and graph nerd.In the professional interest department, I'm always looking at new / low cost ways to monitor, measure, quantify electricity and power. The price point here was minimal ($100). The functions and feature set (monitoring demand, wireless display that can be moved throughout the home, USB interface to access data and produce reports, software to facilitate all that) all looked great.
From an energy conservation / cost savings perspective, although I'm a single person in a small condo, I'm a bit of a nightmare in terms of electrical usage. My condo is all-electric (heat, stove & oven, water heater). Although cooling season is over, I have two small window A/C units (bedroom and basement office), a basement dehumidifier, and a basement space heater. Besides normal living usage, I work out of my house (so I'm in the basement office a lot) and I practice / teach yoga - my second bedroom is a dedicated practice room and when I practice, I generally crank the heat a bit.
Now, I've taken a lot of first steps to reduce my electrical usage - replaced almost all of my incandescent bulbs with CFL or LED, and replaced all of my baseboard thermostats with either digital units, or digital units with a timer. Digital thermostats = more consistent control (I'm not turning heat up or down based on "feel") as well as more even heating (they have triac controls that can turn heat up incrementally not simply ON / OFF like mechanical units). I keep my heat pretty low, 58F at night, 65F during the day, it's scheduled based on my life, and the thermostats make sure I never leave the heat cranked for more than a few hours. I'm pretty good at reprogramming the thermostats as needed.
But enough about me - back to the Efergy energy monitor. It's arrived, been connected, and is doing it's job. Here's a quick review.
Strictly speaking, the device is a CURRENT monitor. There are two clamp on current probes, but no voltage connection point - it calculates demand based on a fixed voltage, and presumably a unity power factor. Have not determined it it measures average current or true RMS at this point. It samples data on a 10 / 15 / 20 second rate. It's not super accurate, as a result, but it's "close enough" and certainly can provide a good comparative measure of energy usage over time.
It also has a third current probe "port" so can presumably monitor three phase power as well. It appears to be designed for a world market: 50/60 Hz, multiple nominal voltage settings, and multiple rate / tariff units.
The monitor was easy to install. Two clamp-on current probes (A) were connected to the mains coming in. I have a 100A panel, the probes appear to be sized for 200A maximum. The probes are not spring loaded, but use a nice little plastic latch / clip for secure connection, and since there is no voltage monitored, the vector / direction of the probe does not matter. I'm comfortable sticking my fingers in a live panel, but to be safe, kill the power before installation.
These are connected via a fixed cable to a transmitter (B) which is powered via 3 x AA batteries, or an optional DC supply. The company claims battery life of 8-10 months is typical for both transmitter and monitor.
The wireless display / monitoring unit (C) can be located anywhere convenient; I placed it atop the panel for the photo. It's powered via 3 x AAA batteries. The transmitter / monitor are linked via a simple push-button procedure. I had no problems getting them to talk. The expected range is 100 - 200 ft. although I found signal was sketchy up on the second floor.
The past week I've had the wireless display sitting on my desk as I've worked, and have enjoyed (yeah, I'm an engineer, what do you want) watching the kW measurement track up and down as I work throughout the day.
Monitor / Display Unit
The display for this device has some rudimentary information. There are three values available:
- Energy Now (KW)
- Cost (per day) based on present energy ($)
- CO2 (per day) based on present energy (KgCO2)
The device allows you to set up variable rate (single or multiple) in cost / kWHr, and a CO2 usage factor.
The display is pretty rudimentary; and if I were relying on that I'd probably check out the Efergy Elite True Power Meter (more sophisticated measurement, more advanced display, temp & humidity) but that device does not have "in the box" communications capability to a PC, and I am all about the data.
The free to download software, elink, is pretty spiffy. The basic HISTORY function displays demand on an hourly basis (per day), a daily basic (per month), or a monthly basis (per year)
Under the MANAGE function, the user can look at individual days, do a weekly comparison (for instance compare individual weekdays or weekday vs. weekend), as well as a month by month comparison.
Finally, there are some advanced options of tracking actual usage vs. planned usage, setting up complex utility tariff schedules (for those working with peak / off-peak billing) and adding multiple utilities (so one could presumably compare different rate schedules with actual historical demand data)
Last but not least, the software gives the option of generating a Daily or Monthly report - selecting a specific time period, and creating a PDF report. The "Add Stickie"feature is not all that intuitive or well documented, but from the main HISTORY page you can create comments on notable usage or patterns which would be great if one were creating a report for users, management, clients, etc.
The exported spreadsheet is pretty rudimentary: Date / Time / KWHr / Daily Max / Cost / Stickie Note(s). Including the Stickies is a nice touch. But really, the PDF report is pretty much all I might need.
Using the Efergy Demand Meter
I can think of a lot of ways to use this device.
Professionally, it would make a great tool to do short and simple residential / small business demand audits. Hook it up, perhaps do some walking around turning things on and off and recording the demand, then leave it connected for a week and generate a report, with recommendations for savings.
As an end-user, I'd probably first characterize the household energy consumers. I'll be able to (over time) generate the cost (in electricity) for things like a load of laundry, a shower, a hot bath, and factor those in a bit. Might even consider replacing older / less efficient appliances. Same with cranking the heat for a yoga practice or fine-tuning the heat schedule and zoning. And although I've gone through the condo pretty well in terms of replacing incandescent bulbs and other energy hogs, perhaps I'll find something I've missed - most consumers who have been less fanatic than I will probably find a lot of room for improvement.
I can also watch the electrical demand on a real time basis, and if I've left something on (stove burner, iron, etc.) I should be able to spot that quickly.
Bottom line, really nice piece of technology - really well designed (hardware and software) and useful.