Sense vs. Ecobee: Round II

So now that I have cleaned up my incoming data a little, I’m going to bring my AC compressor detections into the mix while keeping my smartplug based blower fan detections for both furnaces. One of my goals is to see which of my Sense AC compressor detections reliably line up with corresponding Ecobee run time commands. But it’s a little tricky because:

  • I had one Sense runtime detection, AC, against my old compressors - Detections started showing up on April 7, one day after I installed the new Sense, but I believe that my data is also post-processed for detection so that an detection discovered later can be be run on earlier data to do additional identifications.
  • I had two more detections, AC2 and AC3, that showed up in May and July respectively. The July detection appears to be tightly linked to one of my new AC compressors since it only appeared on July 9th, after the new compressors were installed.

Looking just in the first correlation column, comparing the Ecobee cooling command times/hour, vs. the corresponding AC detections’ power usages for corresponding hours, the data is very clear.

AC correlates with the cooling of my old upstairs unit (May is red, green is June, Blue is July)
AC2 correlates with the cooling of my new upstairs unit.
And it appears the the new compressor, AC2, is more efficient than my 20 year old unit, AC, maybe 1.5kW, vs. 2.5kW in usage.

I’ll also make one more important point here - it looks like there are a bunch of points in the AC and AC2 vs Up_Cool chart where AC or AC2 look to be zero, but are really just very small. Digging deeper, those are mostly cases where both AC and AC2 were detected at different compressor startups during the same hour, but one of two predominated.

AC3 correlates with the cooling of my downstairs units

That’s exciting - Sense is making some solid identifications. But now comes the tricky part, looking for device usage that Sense missed. Remember that these graphs are done with any “missing” Sense device data marked as NA and removed from the graphs.

Because of the way that Sense shares exported hourly data, there’s no way to differentiate between subtle differences in data composition. When Sense presents non-zero data for a particular hour, you can be sure that it “saw” a detected device using power during that hour. But when Sense leaves out an hour of data from export, it could mean a number of things about the device:

  • The device hasn’t been detected yet
  • The device has been detected, but wasn’t spotted running during that hour
  • Sense encountered a data dropout
  • Or a mix of the latter two

So I’m going to try to do two things for additional analysis

  1. Replace the NAs with zeros again (treat all missing zeros) and see what happens
  2. Try to intelligently convert NAs to zero, but only after Sense has started to reliably detect those devices, to see how much real runtime Sense might have ignored - hours where the Ecobee is telling the compressor to cool, but Sense doesn’t give any data for that device hour.

Here are the same charts with option 2). I have converted all NAs from Sense to 0’s, and only selected data after July 9th, when my new AC compressors were installed. An interesting
pattern emerges:

Up doesn’t look so good - looks lots of “zero power” in both AC and AC2. Poorly defined correlation “signal”. But just like before, when I push down into many of those zeros, they are really cases when Sense detected a little bit of power as AC and most of it as AC2, or vice versa. If I was to correct the graph by adding non-zero AC power to corresponding hourly AC2 power, I bet we would see a clearer signal (later).

AC3 gives a strong clear “correlation signal” with respect to the Ecobee Down_Cool requests. There still look to be some missed detections, but not many as @ixu is seeing in his excellent correlation analysis here:

So one final experiment, adding AC and AC2 power to handle the case where Sense gets a little mixed up between the two, when identifying my upstairs AC unit during the same hour. I probably should have deleted AC once my old AC units were repalced, but I wanted to do this type of experiment first. Here’s a more detailed vie of just Up_Cool (Ecobee command time) vs. ACcomb (AC+AC2 energy), with FurnaceDown smartplug detection as well.

There are now fewer missed identifications (near zero power for positive runtimes) in the ACcomb graph, but the “signal” is still a little fuzzy. Some of the points follow a trend line that indicates a 3kW device while other for a 2kW device line, but that’s to be expected since we’re seeing a mix of identifications, when my older AC unit was less efficient.