Cost lever Sold under many names
Krypton fill
An inert gas denser than argon, sealed between panes where the gap is too narrow for argon to work well — mainly the thin gaps of a triple-pane.
What it means for you
Not an everyday upgrade. It's where you buy insulating performance in a slim triple-pane that can't fit an ideal argon gap. On a standard NC double-pane, argon is the sensible, cheaper fill.
Where you'll see it
On triple-pane spec sheets; rarely on a standard double-pane quote.
Also sold as: krypton gas
Related terms
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