My office gets the sun beating in through the window from about 2pm till sunset, and the curtains just absort the heat and act as a radiator. They're blackout curtains, so I think I'd have to swap them for white / extremely light coloured thin curtains to help with that maybe.That curtains / blinds thing doesn’t seem to make much difference for me.
I've never bothered with the window kit. It's only open enough for the exhaust to stick out. It's always been great without... a few times today I've felt a little chilly actuallyNot fitted the window kit yet, but the unit's already having a sizeable difference on the temperature of the room.