I am also in Chicago and in an old building. I am near the lake but unfortunately only one of the windows opens because they are so big. On some days I am lucky enough to have a great moderate breeze. When it is in the higher 80s (which it luckily has not been so far this year) I close the window and turn on the AC. At certain points in the day, I turn off the cooling element and just use the ceiling fans that are in every room and which are great. I especially like a cooler room for sleeping. Chicago seems to have its bad and good months depending on the year. There are some weeks where it is absolutely beautiful whether and you say to yourself, "This is why I live here." Then it can turn to the 90's and high 90s and you want to pack up and go. Then again eventually winter comes and it can get so cold you do not leave your house unless you absolutely have to.