[Sohcahtoa82]

Interesting. Someone had told me that the Nest figures out if you're home by recognizing the presence of your phone. I wonder if that information was wrong or only applied to a specific version of the Nest.

At one point, I had a cheap WiFi thermostat. No smart features, just allowed remote control via app or web page. At one point, I had reverse-engineered the web app API and wrote a script to implement "away" detection and shut the thermostat off if both phones were away.

The problem was two-fold. First, it detected the phones being away by simply pinging the phone's local IP address. If the phone was in a power saving mode that disabled WiFi, the script would detect the phone as away. Second, I ran into the problem the article author had: If everyone was away, it got cold in the winter, and an absolute oven in the summer, and my aging A/C unit couldn't get the temperature back down until the sun went down.