Unlike a cracked pane, gas leakage is invisible. You cannot see the gas escaping. However, there are distinct warning signs that the seal has failed and the gas is gone.
Dense, noble gases like and Krypton are much heavier than air. Their molecules move slowly, significantly hampering the transfer of heat and cold. Replacing air with these gases is like replacing a screen door with a solid one—it creates a much more effective thermal barrier. The Most Common Window Gases 1. Argon Gas
To understand why manufacturers use inert gases, one must first understand how heat transfers through a window. Heat moves from warm to cold areas. In the winter, the heat inside your home tries to escape to the cold outdoors.
If you stand near a window that was previously efficient and suddenly feel a draft (or a distinct cold spot), the gas fill may have dissipated. The window is now conducting heat much faster than before.