Until recent years, windows were sold without "trickle" vents fitted............... small vents that allowed vapour to escape without the draught that is inevitable with leaving a window open.
Early aluminium windows had no "thermal break" either. That is to say, the inside surface of the frame was at the same temperature as the outside .......... cold!
As RATT says, have the inside temp as low as the outside ............. probably not practical though. Or, have a comfortable temp but with a couple of casements sightly open.