None of my windows open in the house, and the windows were entirely built with the house plus I figured out, built into the house. I would have to detach the siding in order to rip out the window, and so that means if I want new windows, I have to buy from a supplier plus have them install it. I have a lot of windows in my home. I also have a lot of sizable windows too. So the cost of the whole job would be so much currency. It makes myself and others sick to my stomach even thinking about it. However, I don’t know I can go on without being able to open my windows, right now my boyfriend requires our Heating, Ventilation & A/C unit to run 24/7. In the Winter it is heating plus in the Summer it is heavy cooling. It circles the same, stale air over plus over again. Have you study any stats on indoor air quality? The indoor air is so much more polluted than the outdoor air. I also own a cat plus he uses litter. That is a lot of odors, hair plus dust that is going into my HVAC duct plus coming back out again. I don’t need an air purification system, I just need some fresh air. There are months at a time that would be wonderful with fresh air only. I wouldn’t need to run the Heating, Ventilation & A/C plus I could save some currency. I also would get cleaner air moving through the condo plus adding freshness. Right now my boyfriend plus I leave our front door open. That just lets in bugs though.