Why is Argon used for double glazing glass and how does it benefit the windows?

There has been much in the press and on television recently about making your home energy efficient and trying to reduce your heating bills by taking steps to improve the insulation or to stop heat escaping through doors and windows. Once of the best ways to do this is by investing in replacement double glazed windows. A recent government scheme has enabled consumers to compare windows more easily by introducing a ratings system on a sliding scale to grade the energy efficiency, and some of the windows which score higher on this scale are often filled with an inert gas called argon. Why is this used and what benefits does it have?

How are windows constructed?

Whatever firm the homeowner is using to install their windows, the method of constructing them is broadly similar. Any standard double glazed unit is formed of two panels of glass, held separately in the frame with a space between them. This space, known in the window trade as the cavity, functions as both a barrier to sound and helps to retain heat within the home. The exact gap will depend on the way the windows are built, but is typically around 15mm.

Traditionally, air has been used to fill the cavity between the panes. A vacuum is formed, then filled with specially dehydrated air which means that condensation does not have the chance to form between the panes as there is no moisture. In recent years, double glazing companies have been starting to use a variety of inert gases to fill the gap instead of air, most commonly argon. Using argon in the windows is perfectly safe and does not affect the way the windows are made.

Benefits of using argon

Argon is a completely different gas to the air we all breathe, which is primarily a mixture of nitrogen and oxygen. Argon is naturally present in air, but when used on its own to fill windows it helps retain more heat than using air. As this technology is new, windows filled with argon can be up to 5% more expensive than windows filled with air alone. However, studies have shown that filling windows with argon rather than air can increase the efficiency of the windows by up to 30%. This means that although the initial investment is a little more, the amount saved off heating bills will be far greater, meaning that the increased expense will pay for itself many times over the course of the lifespan of the windows. Argon gas does not leak from the windows, and will not need to be “topped up”. It also has the same properties for reducing noise as ordinary air, and due to the benefits of using the gas, argon is likely to be the default choice for windows in years to come as companies strive to produce ever more energy efficient windows.