Sense Home Energy Monitor – Initial Thoughts
A few months back someone asked about electrical load monitoring tools. I promised that I would give feedback on the Sense Home Energy Monitor once I had a little time with it.
Here are a few initial thoughts after a month of use. (I don’t know anyone at Sense or have any financial interest in the company.)
Sense is already changing my lifestyle. A few examples:
Example 1. Sense popped up that I had two refrigerators. I thought “no, that is wrong I only have one, stupid software”. Then it dawned on me, I do have two refrigeration devices, there is a little chest freezer in our mechanical room. Turns out that twenty year old nearly empty freezer uses more energy than our two year old side by side fridge in the kitchen. It’s going to go bye-bye.
Example 2. Sense said “you have a little electric heater that cycles on and off in the evenings”. (It doesn’t talk but if it did…) No, I am not running an electric heater, what are you thinking? Oh, wait, that is the glow bar ignition circuit in our gas oven toggling on and off. Wow, I didn’t realize that was a “bang-bang” circuit; I assumed the oven lit and then the gas valve (flame level) was modulated. Learn something every day.
Example 3. Our hot water is heated by “surplus” desuperheater heat off the geothermal compressor. This means that the electric resistance element in the hot water tank rarely runs. Guess what, Sense pointed out that I often shower, use the washing machine, or run the dishwasher at times this wasn’t true. For example, on a sunny day we won’t use heat (passive solar home) so the geo system doesn’t run as often. So if I wash clothes in the middle of the day I actually end up “firing” the hot water heater. (There is of course a balance, as I often hang clothes out to dry versus using the electric dryer.)
Example 4. Our “Always On” load runs around 800 – 900 watts. It’s made up of HVAC controls, computers, routers, security system, aerator on our septic system, heated towel bar rod in the master bath (OK, the towel bar is a luxury..), etc. In starting to think about how to prune that load I have already begun dialogue with the septic tank manufacturer about putting the aerator on an energy saving VFD. Why? Because now I have a means of knowing when the water well pump runs, and as such I can link water usage to septic/sewage flow!
Andy
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Andrew. Thanks for sharing. Did you consider any other monitoring systems before buying the Sense, and were you able to do the installation yourself?
Thanks for posting this. I am contemplating getting one of these and appreciate the review.
Steve, contrary to my normal inclination to over analyze things, this is an instance where I pretty much decided on the spot that this was the way to go. I was approached by a next gen energy system vendor about possibly being a beta site. (I don't have any PV etc yet.) They wanted to know an electric load breakdown by device; I didn't have it. An engineer I respect had asked whether I knew about Sense. I looked at Sense's materials and pushed the "order button".
As to install, yes I did it myself. I put the unit outboard running the cables through insulated bushings (fittings) that I supplied. It's on a 20 amp double pole breaker. It could have gone in the panel, but it would have been tight, and I am not sure you could have heard the little "beep" when it syncs up to a network. I attached a quick picture.
Note however there was a time in my life where I did commercial electric work up through 480v 3 phase, have installed permitted and inspected new services, worked on industrial controls, etc. So I probably shouldn't be considered a typical homeowner. (This, like the painting I didn't do, aggravates my wife. We hired professionals for almost all of that work in this new house. I think it's generally better to use people that work these trades daily.)
Two more Sense screen captures showing usage by month and week. Stumbled on how to toggle to these on the iPad only a day ago.
The "Unknown" ratio is slowly going down, as Sense does a better job of parsing loads, largely when the geothermal compressor is running. That is the sole direct contact I have had with the company, an email thread pointing out the random times where Sense missed that the compressor was on. Based on their recent Facebook Live Video session, HVAC system identification is one of their focus areas.
My personal focus is trying to trim the "Always On" loads. For example I just put the Bunn "water heater" style coffee maker on a timed control so it isn't always on. Getting old, can't drink coffee after lunch anymore.
Our electric runs around 10.5 cents per kWh (plus sales tax and $6.18 of distribution fees each month).