Sense Is Helping Us Become Net Zero!

Device: Other Device
Make: Solar Panels
Model:
Estimated Savings:

We installed solar panels just before the end of last year (2018) and installed a new Sense Monitor at the same time. We have 15 rooftop panels on our old DC rowhouse, a 4.875 kW array in total. Our goal is to see if we can be a net zero energy home by the end of 2019.

Our electric bill while it varies from month to month can be as much as $1,000 per year especially after AC use during the hot DC summers. As a sustainability guru and Architect, when I heard that Sense was a smart home energy monitor capable of detecting appliances and other home devices, I was all in and ready to get one installed.

Dehumidifier savings

Device: Dehumidifier
Make:
Model:
Estimated Savings:

My dehumidifier was running all of the time so I took a look and was able to adjust it limiting the run time and lowering my energy usage.

TV turned on randomly when not home

Device: TV
Make:
Model:
Estimated Savings:

I noticed sense showing a TV on, when nobody was home and I was sure it was off when we left. Turns out part of my home automation system was periodically checking on devices which caused my TV to power on. It then stayed on until the default sleep timer of 2 hours hit!

Identified a short cycling AC!

Device: AC
Make:
Model:
Estimated Savings:

I’ve had sense for a week, and it (mostly) identified my AC after 2 days. I quickly noticed that my AC was starting and stopping a lot. For example, yesterday between 1 and 2 it cycled 6 times, running for as little as 5 minutes at a time and cycling back on with as little as a 4 minute break.

I did some research, and learned that short run times are inefficient and don’t let the system do a great job of dehumidifying the house (mine is very humid!). Also, short cycling is bad for certain components of the HVAC, causing them to break down more quickly.

After some investigation, I’ve determined that the short cycling is being caused by having many zones in my house, having a slightly oversized unit, and having thermostats with a 0.5 degree unadjustable swing differential. To fix this, I am buying new thermostats for each zone with adjustable swing differentials, which I plan to set to 1.5 degrees. This should make my AC run longer to reach the cooler temperature and take longer before needing to run again.

Reducing short cycling should make my house more comfortable by better controlling the humidity. It also should immediately save me a little bit of money by letting my unit run more efficiently and reducing the amount my dehumidifiers need to run. Finally, it should save me money in the long run by reducing the wear on my HVAC from too many startups.

Sense found a mistake in my thermostat settings

Device: Floor Heater
Make: NuHeat
Model: Signature
Estimated Savings:

We recently installed stone floors downstairs along with associated in-floor heating. We chose stone for the look / durability, but also hoped that the additional thermal mass would help keep the house cooler in the summer since we have warm-hot days and cool nights most of the year. To do that I thought I programmed all four of the floor heater thermostats to 66 degrees for 11pm to 10am for the summer season.

I was therefore surprised to see a new device show up this morning, that the crowdsourcing picked to be a floor heater. Especially bad given that the air conditioner is running a bit during the daytime during this season. I took a quick look at the Sense device waveform, then because Sense thought it was floor heater, consulted the NuHeat app to find that my Guest Bedroom heat usage waveform matched exactly ! But why was it on ? User error – the Guest Bedroom nighttime setting was 68 degrees ! I was quickly able to adjust the thermostat down.

“Fast Start” mode is expensive!

Device: TV
Make: Hisense
Model: 50R7050E
Estimated Savings:

My Hisense TV consumes ~30W more in “fast start” mode vs. not in fast start. I had no idea the difference would be so large! The main benefit to Fast Start, besides saving a few seconds when turning it on, is being able to reliably turn the TV on via my iPhone’s Roku app… the realization that this was costing me ~$5/mo made me realize I’d be better of just using the regular remote!

“Circulating the air” is not worth the price

Device: Furnace
Make:
Model:
Estimated Savings:

I had my thermostat set to run the furnace fan for 15 minutes every hour. In my mind it would help circulate the air, in summer it would bring cooler air from the lower level upstairs, and vice versa in winter.

I of course knew there was a cost to this, but I didn’t know how much power the fan consumed. It was a decision made in haste when setting up the thermostat, and because the fan is so quiet there wasn’t much to make me question that setting.

Sense helped me with humidity setting

Device: Dehumidifier
Make: GE
Model: APEL70LW
Estimated Savings:

I’ve been wondering about what humidity level to set my new GE dehumidifier to. I started at 40%. Too dry and wood starts to crack and the dehumidifier runs too often. Too damp and the tools rust.

Also, in the back of my mind was the women at Home Depot who said she got a notice from her power company that her power use went way up after she installed the same model (I think it was broken, or her basement is very damp, and/or she had it set too low).

Then there was the Home Depot sales guy who assured a couple of us that if we set 60%, the dehumidifier would run cooler over all, and last longer.

Low Power TV is not so low power.

Device: TV
Make: Sony
Model: XBR-65X900E
Estimated Savings:

The combination of my Sense and a TP Link HS110 made me aware of how much power my TV actually uses in idle. Spec is 0.5w, but in practice, it is actually more like 18w spiking up to 35w several times a day when checking for updates.

I have the TV set to “Eco” mode, but it seems even in that mode, it still stays in a “Fast start” mode so that Android TV doesn’t have to cold boot every time, so it stays in a warm state pulling more than the suggested .5w

Pumping on empty

Device: Pump
Make:
Model:
Estimated Savings:

When I installed sense I noticed an unknown 600w load from 6am to noon every day. I have an aerobic septic system that the irrigation spray pump was on a timer with a shutoff float switch. After some basic testing I realized that the pump was on for the ENTIRE TIME it was set to even after it had emptied the tank. About 5 hours more than it should. I could use Sense to determine the optimal time to change the timer to empty the tank while minimizing the ‘pumping on empty’ waste.