Argon Gas Fill

Argon gas is used in approximately 90% of residential insulated glass units manufactured in the United States. Argon is a naturally occurring inert gas that makes up about 1% of Earth’s atmosphere. It conducts heat roughly 34% less efficiently than air, making it an effective insulator for the space between window panes.

Why Argon Instead of Air?

Plain air is a reasonably good insulator, but it contains moisture and convects heat (warm air rises, creating a slow circulation loop inside the cavity). Argon is denser than air, which suppresses this convection. It is also completely inert—it won’t react with the glass, sealants, or coatings over time.

Argon vs. Krypton

Krypton gas is denser than argon and provides better insulation, but it costs significantly more. Krypton is typically used in triple-pane windows where the cavity gap is narrower (6mm vs. 12mm for argon). For standard residential double-pane windows in Ohio, argon is the practical choice.

Does Argon Escape Over Time?

All IGUs lose a small amount of gas over time—industry standards assume about 1% per year, meaning a 20-year-old window may retain 80% of its original gas. This gradual loss is acceptable. However, when the seal fully fails, argon escapes quickly and the window loses its thermal advantage.

Can Argon Be Refilled?

There is no practical way to refill argon in a failed IGU. When the seal is broken, the correct solution is to replace the entire IGU with a new factory-sealed unit.