Trying to Explain Cold Weather "Always On" leaps

[jrsaxe]

Hi All!

I considered posting this on a 10 month old post about ways your “always on” number could be deceiving (incorrect?), but figured my question was a bit different, so I thought it made sense to start a new topic.

Background: I’m a more passive sense user in that I frequently won’t check my data for a month or two, but will dive in when I’m trying to diagnose an issue. The issue I ran into was a HUGE electric bill and I dove into my sense data to try and find out why!

I live in Washington DC and have a gas furnace, so my highest electricity bills are typically in July and August. Last summer we hit 1399 KWH (net of solar) on our pepco bill. In December with hit 909 KWH (also net). In January we hit 1752 (net…)! January was particularly cold in DC so the usage is likely connected to the cold.

My always on activity is very weird and contributed a ton to my bill.

Here is a typical month:

Here is last month:

You’ll note that some days the always on usage was the same level as prior months ~8 KWH or about 333w, but for certain days it rose to more than 33 KWH to 1300w!

I looked more closely at individual days and I see some weird patterns!

300w increase to 600w

600w increase to 1300w

The obvious culprit here is my gutter heater/defroster that has a simple thermostat that goes on when it’s cold and stays on. However, I’ve cycled this manually and it only draws about 300W as far as I can tell. This would explain the first leap in the always on (but would likely lag 48 hours after the thermostat kicked on), but any thoughts on what types of circumstances would trigger the second leap? This could be due a specific device turning on and staying on, but I thought it might also be something that is getting bucketed into “always on” for some technical reason rather than new load.

FWIW I did check my Pepco daily usage and it tracks sense pretty well (and solar while variable was pretty flat, so it’s defintiely something on the load side of the equation).

[kevin1]

@jrsaxe ,

Home level Always On isn’t bucketed - it’s just math-based, on the power on each power leg in your home. You seem to understand that based on your 48 hour delay comment.

How are 'Always On' and 'Standby' calculated?

Do you have a heat pump ? Maybe your heating strips kicked in (showing up 48 hours later) ?

Also worth reading this, especially bullet #5

Five Things to Know About 'Always On'

[Always On] Always On can be a confusing and controversial “measurement” for some users. But it serves a real and important purpose for users who want to accurately account for their energy usage. Always On is Real - Many devices have an Always On component, that the traditional Sense detection, based on on/off transitions, can never see. For some electronic devices like routers, modems and switches, virtually all their usage is Always On. Most appliances consume both via Always On usage, w…

[jrsaxe]

Thanks for the response. I almost replied to that post, but figured my questions were a bit too specific to latch on to that general information.

I don’t have a heat pump. The other thing that obviously runs a lot more in the winter is my whole house humidifier. I have it set very high (38%) because my wife really hates dry air. It’s hooked up to the hot water line, which means that when it’s running it will use a decent amount of hot water. That said, the hot water heater is identified by Sense and should never be swept into the always on (even with a constant trickle, the heater does cycle).

It could be the fan in the humidifier, which I don’t think Sense has figured it out as a distinct device… but it’s a small fan, so no way do I think that could draw 600w plus… Once I figure this out, I will respond to this thread to close the loop.