Most people have never seen windows like these. European style, tipple pain, argon gas filled, no thermal bridging, R-8 for the opening windows. German Passive House certified. KlearWall windows, the North American branch of Munster Joinery and are made in Ireland. Here is a thermal image of the windows performance. Out side air temp 15 and inside temp 65.
How they work: First the handle, when down the window is locked. Then, when at 90 degrees the top tilts in for ventilation. Lets air in but keeps the rain out. Also secure enough to leave open while your gone.
In the up position the window swings in. Wide open. The Europeans say they only do this for cleaning. A friend in a passive house says the same thing. He says the tilt opening is more than enough ventilation.
Note the latching mechanism. The windows latch in 4 different location to ensure an air tight seal.