Cost lever
Argon fill
An inert, harmless gas denser than air, sealed between the panes to slow heat transfer. A cheap, standard upgrade over a plain air gap.
What it means for you
Nearly always worth it and usually inexpensive. If a quote's glass package skips it, ask why — it's a small line for a real gain.
Where you'll see it
A glass-package line item; sometimes bundled into “Low-E + argon” as one upgrade.
Related terms
Reading this on your own quote?
Run the 30-second check — where your number lands against real NC ranges, plus the red flags.
Check my quote →