That's pretty cool, I was thinking about building my own thermostat a few years ago.

My previous one died and the company stopped making them. But what I really liked is that it was a "smart" thermostat that was made before the IoT age.

It was "smart" in a way that it had a motion sensor and basically just turned on the heating for 1 to 3 hours after it saw motion. The duration was something you could set yourself.

I really liked that concept, because I never had to change anything during a holiday or even a night in a hotel. If you aren't at home, no motion, no unnecessary heating.

The thermostat was in a pretty central place in our house so you would definitely trigger it every 2 hours when getting a drink or using the toilet.