OP’s post is a good lesson in the value of metadata and how important data privacy protections are.

I have a Dyson smart air purifier / heater combo in my room. It has a mostly real time app that shows whether the air is healthy or unhealthy. One night I was laying in bed and felt some gargantuan ass thunder brewing, so I aimed my cheeks toward the Dyson and watched gleefully as my air quality went from green to red. Technology is amazing.

I learned my air filter uses almost no electricity so I just leave it running 24/7 now.

Tell me more about automatically watering plants

• My TV’s power consumption is basically doubled when the input is running at 2160p compared to 1080p.
• Running the portable AC in my office for more than 24 hours causes it to cycle off and on because the humidity collection sump fills up and needs to be emptied (it throws a completely unhelpful error of ‘Low Temperature’).

While not publishing it, my weather station uploads my indoor temperatures to weather underground. The plaintext password is in every packet. It uses unencrypted HTTP.

My TV continues to chatter to random servers on the internet long after it has turned off. It transmits to a telemetry server on every single button press.

My air conditioners drain a lot more power when I haven’t cleaned the filters. It’s almost double.

A chromecast will try to bypass your router’s DNS and go straight to Google’s. It is constantly pulling data even if you’re not using it. I’m fairly certain it’s that slideshow. It’s not cached at all.

Onkyo home cinema amp was eating 50W when being “off”.
Fixed it with smart multi-plug which power the amp when the tv is on, and cut power when tv is off.

Minor and obvious thing, but seeing it plotted finally made me recognize it: the temperature on my balcony is consistently lower than temperature inside my fridge for a good part of the year.

A friend in HVAC told me each person produces 350 btu of heat on average

My old Samsung printer can enter a state where it consumes ~100W without doing anything meaningful. It’s not obvious what is wrong, but without power monitoring I would have never realized this.

CO2 levels raise astonishingly fast when people are present in a room.

I have mice visiting my garage and I can tell when by looking at the motion sensor history.

My uninsulated roof stays frost free even at -15°C.

The biggest one was probably a combo of having an anemometer, and heat/humidity sensors in each room.

When it’s cold outside, the top floor of the house (loft conversion) loses more heat. But it loses significantly more heat when it’s cold, and the wind is blowing parallel to the floor joists.

I realised that because they’re not perfectly sealed (old house), enough air pressure means that the floor void can easily hit external temperatures, meaning the rooms have cold on twice as many sides.

I will (eventually) get some suitable insulation in them to stop this.

By recording the electricity use in my house I noticed a 1500 watt spike at a semi-regular interval. It would happen every 50 minutes and lasted for a few minutes. While overall not that much of a draw, it sort of drove me crazy not knowing what it was…

Then I discovered that it was our septic system’s effluent pump (the leach field is up on a hill). The pump was turning on way too often because ground water was leaking into the pump chamber. It’s not supposed to do that. The tank was about 45 years old, so not a huge surprise really.

Basically, my home automation (or tracking, really) lead to an $8k concrete tank replacement (more or less, as we had the guy do some additional stuff while he was here).

That’s not really a bad thing though. Maintaining your house is very important. Our well had failed a coliform test the previous year, and I’ve yet to get it re-tested to see if the new tank fixed that little problem. I’ve been giving everything some time to settle down.

The humidity in my apartment is affected far more by cooking than by showering.

I’ve caught the front door and garage door left open several times (kids)

I found out my garage under my bedroom is primarily why my room is hard to heat and likely has poor insulation in the ceiling.

I found out my Samsung TV was sending a LOT of data home.

I know every time my Roomba gets stuck so I can go and locate it before the battery dies.

I know when my unraid Dockers fail to update and accidentally delete the old containers, so that I can go and re-add them.

One of my children were doing remote learning and I would get an alarm if he didn’t get up in the morning and start using his Chromebook.

I can see if someone is on the toilet and having a Nr.2 by checking the power draw of the Japanese style toilet. (I also have a presence detector). I do not monitor the first part intentionally, though.

I unintentionally catched some birds eating on camera and that led to us installing a designated bird cam - in a 3D printed bird house. The AI model for identification is still in the works though - there aren’t any good European based ones available as open source so I still will need to work out my own.

I found out the kid is reading FAR more than thought and is using the PC far less than I thought. Sorry kiddo!

CO2 is going up far more than expected,yes. What I found more interesting, though, is the direct connection between the humidity and my sinus infections - I always get them if my room air gets to dry.

Cooking releases an ungodly amount of VOC and uses FAR more electric energy than I thought.

And: After two years of optimisation I can control the temperature in two very sun exposed rooms just by using the covers and a weather forecast extremely well. Means they are up to 4° colder in the summer than before and 10° warmer in winter. Sadly this does not apply to all rooms.

And last but not least: Heating is the only point where home automation really saves energy here.