I wish there were something that opens the windows automatically at the right time to keep the heat* and humidity out. I'm sure other people will have had that idea, too. But I haven't come across easy-to-use hardware controls. That's not even talking about the full optimal control problem, i.e. weather forecast, the heat capacity and heat permeability of the walls, and any cigarette smoke coming in.

*Air conditioning is hard to get permission for as a renter in Germany.