I stand corrected. You know how the aircraft window system is manufactured. I don’t understand the lack of vacuum which is much better than gas (air) insulation under normal (cabin) pressure.
I judged by what I know of Andersen windows, two panes and vacuum in-between. I thought more temperature/pressure requirements for an aircraft.
I very much doubt there is vacuum in-between two window panes unless they are very small. At 15 pounds per square inch, a window would shatter unless it's very thick, or very small.
I would think they would use nitrogen or something.
Oh, I don’t know much about airplane windows... I just wondered what that little hole was for long ago. (I always request the window seat.) That’s the only reason I know it’s cabin pressure between the two structural windows.