(Well, currently, we're trying to go as long as possible without it, so it's a toasty 85 in the house, but with the windows open it feels not so bad)
So that cuts us down from trying to cool 2500 square feet to 200 square feet for about 10 hours.
But, those accordion panels on the sides let in outside air and let out cool air. Not good, so how can you make that better? Duct tape. And what's nice, is duct tape comes in colors, pick the color right for you (most likely white) and seal that puppy off. No more tacky than the accordion thing. Energy efficiency goes up the less drafts you have coming from the outside (see my caulking post)