IGU
insulated glass unit
The sealed sandwich of two (or three) panes with a gas-filled gap and a spacer around the edge. The “glass” in a modern window is really this whole unit.
What it means for you
When people say a window is “foggy,” the IGU's seal has failed and moisture got between the panes — often you can replace just the glass, not the whole window.
Where you'll see it
Not named on your quote directly; it's what “double-pane” or “triple-pane” refers to.
Related terms
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