What Is Argon Gas and Why Is It Used with Low-E glass?

Argon is a safe, odorless, colorless, non-toxic, non-flammable, inert gas that is commonly used in place of air between the glass panes of an insulated Low-E glass unit.

Argon’s heat conductivity is lower than that of air, and thus it is a better insulator and contributes to a lower U-factor. Argon is not an effective solar performer by itself; that is why it is only used in conjunction with Low-E glass.