> In comparison when i lived in Russia we had double glazing but the gap between the panes was about 9 inches wide.

That's the older way of doing insulation. Here in Germany houses from around 60 years ago are likely to feature the same.

It was quite a shock as i'd never seen it before growing up.

In the UK we had a bit of a double glazing boom in the late 70s, highlighted well in the TV show "White Gold"

This generic PVC stuff became so common place i'd never seen anything else and just assumed the rest of the world was the same.

And that's the kind of window which makes ice flowers in freezing times! Oh, childhood memories...