This is a POC I made for a friend.
Looked it up on the net and decided to give it a try.
The setup is made of a DS18B20 temp sensor to mesure room temperature and start a fan to cool the room.
It has two 3,7V Lipo batteries to power the 12 V fan and it increses fan speed as temp increases from 27ºC up to 32ºC.
https://www.youtube.com/watch?v=W08njOb1rD4