Now you are talking, I have looked at this idea, but other than use a PLC which I have considered as I have a couple spare, how do these things work? My first thoughts was the Inkbird
View attachment 344046set it so when outside at say 24ºC the fan stops. But it would need two, one to start the fan when inside temp 18ºC what is really wanted is if inside is over outside temp, and inside is also over 18ºC then run that fan. A if this then that (ITTT) setup.
So fan is already on a wifi socket TP-Link one I think, so hey google turn on fan will work, that helps as I can set the fan to stop at set times, or start at set times, and use voice to override the times.
However if one keeps the home cool that's half the battle, once the home has heated up, it often too late to use fans. It turn the AC on time.