1 year Observations

Today is the one-year anniversary of my starting up my Sense monitor so I thought I would share my experience and observations about Sense performance.

Sense has detected 30 different devices in my home including all the largest energy users. My biggest category continues to be Other, at about 30% of total usage, followed closely by Always On (158 average watts over the year). Sense has not detected any lamps or light fixtures that use CFL or LED lamps and they may constitute a significant part of the Other load.

My largest energy consuming device is the refrigerator (876 kwh/yr). It’s nearly 30 years old so I guess that relatively high usage is to be expected. The freezer, which is much newer, uses barely a third of the fridge’s energy consumption.

The biggest single load in the house is the electric oven which uses about 3600 watts in the Bake mode. Unfortunately, Sense only detects about 70% (2500 watts) of this load so its statistics for the oven’s energy consumption are too low. Apparently Sense only detects the 240 volt lower oven element and does not recognize that the oven also operates the upper “broiler” element at 120 volts in the Bake mode.

A 30 year microwave that is a part of my wall-mounted electric oven was promptly found by Sense and is reported reliably. A newer inverter-based table-top microwave has remained invisible to Sense.

Devices that cycle on/off frequently seem to be more easily detected by Sense that those that switch infrequently. Sense quickly detected a 1500W thermostat-controlled bathroom space heater, but has ignored two other radiant heaters (500 and 1000 watts) that don’t have a thermostat.

I find that it can be difficult to properly merge devices that have multiple parts operating at different times, e.g. window A/C units have separate motors for the fan and the compressor; gas dryer has both a drum motor and a gas ignitor. I’ve successfully merged some of these devices but, at times, it can be hard to determine which sub-device Sense has detected.

Overall, I’m satisfied though not overwhelmed by Sense’s performance. I guess I’m a “data nut” so I do enjoy seeing the data and check it daily.