Oh my gosh! Open the window!!!
Birds love fresh air, as do any animals.....And it is important to air out a room or it becomes stagnant and stale and nobody likes that.
Think: cold drafts are bad....warm winds are good.
Summer is a great time to have our little feathery friends enjoy the great outdoors, even if they can't get out there and, as a bonus, they get to hear their wild friends chirp.
By the way, even if you open a window a bit in winter for some fresh air, as long as there isn't a major drop in room temperature, you are ok, but always keep a bird out of line of a direct draft.