Not sure if you can tell from the photos but the windows my husband designed are fully functional. They can be opened all the way when it is warm outside or partially when it is slightly chilly. They can also be completely closed when the temps drop to keep out the north winds. Of course they aren't air tight like house windows but they block a lot of drafts. You can see the wooden know at the top center and just barely see the diagonal brace at the bottom right that holds the window in the closed position.