They're all double pane. (Oh yeah, except for the entry door(thanks 8e3k0))
The only thing that I don't care for is that they are all sliders for opening, instead of louver style. The slider track is on the inner side of the fixed panes, and on the picture window in the back the fuzzy stuff in the track gets (stays) wet from constant rain. Had to spray with Lysol a few times to keep it from mildewing.
Also, the large "fire escape" window in the bedroom was not an opening window, but we got one that was a slider from
Kinro for a reasonable price. We did this mod because we are fresh air sleepers, and the two mini-windows in the bedroom slide were not enough ventilation for us.
Overall, I am very pleased with the dual pane windows.