Well, yes. How does it make window units feasible though? I used to rent an old house in California, it had central air but also wrapped wooden windows with sin

Well, yes. How does it make window units feasible though? I used to rent an old house in California, it had central air but also wrapped wooden windows with single pane glass. I ran A/C whole day in the summer and could only get 10F (80F inside with 90F outside), which was a relief but far from ideal. A window unit with an open window, covered in cloth is not going to save you from heat IMHO.