What are the pros and cons of argon gas inside my insulated double-pane window units?

Argon gas-filled windows are currently very popular. While argon-filled windows have significant advantages, they do have potential downsides as well.

Pros

The properties of argon gas help create a more energy-efficient window, reducing heat and cold transfer, and lowering your energy use.

Cons

Unlike in a single-pane window, any leak in the seal of an insulated glass unit will allow the argon gas to escape. This will eliminate any thermal efficiency benefits and can invite in moisture, causing condensation issues.