The cat room fans are standard bathroom fans. At present we just leave them on all the time -- you can see the switches taped down in the photos. I suppose it might be a good idea to rig up a sensor...
Just need: - TVOC sensor like the SGP41
- ESP32 microcontroller
- Electric Relay
Beautiful home and contents, btw! It seems expensive but more than a few folks would have spent the same money on “nicer marble” or something.
In this day of international men’s day, maybe I should still enquire about your internal mental health, because stress can be discreet, but still, the outer appearance you give from your allocation of time and clarity of mind seems absolutely perfect.
BTW it's not a renovation, we build the house from scratch on an empty lot. :)