depending on which part of the country you are in? build a box that is acoustically deadened around your window. that way you can leave the window open about four inches. go to grainger, pick up a six inch blower motor, cheap one is about forty bucks, cfm is 180. use that to supply fresh air into your room. will cool your room no problem. to make it more efficent you can add an exhaust fan as well. just make sure you put something on the exhaust side for odor control.