The short explanation or definition of insulated glass is simply 2 or more panes of glass assembled in such a way to create an air gap between the glass. Of course, the term “air gap” is a bit of a misnomer in that the gap is filled with an inert gas such as argon. An air-tight seal is added to the perimeter of the assembly to keep the moisture out and the gas inside. In essence, the space creates an insulation barrier between the cold air outdoors and the interior temperature of your home. By comparison, a single layer of glass has virtually zero insulation value.
Not Your Grampa’s Storm Windows
Reading the description above you may think that the storm windows your Grampa installed every fall achieved the same results. Sadly, you would be mistaken. While it is true that storm windows can offer some benefit in the cold winter months, they don’t come anywhere close to the insulation benefit attained when installing insulated glass throughout your home. In fact, if storm windows aren’t tightly sealed there may be little or no benefit whatsoever.
Not All Insulated Glass is Created Equal
When shopping for insulated glass it is important to consider all aspects of the window construction. Not all insulated glass is created equal. There are different methods of design including the type of gas between the panes, the type of spacer used, and the sealing method.
Insulating Gas: The gap between the panes of glass is filled with an inert gas. The most common gas used in the construction of insulated glass is Argon. Another common gas is Krypton which may be found in high-end triple pane windows, where the smaller gap requires a gas with a higher insulation value. Some manufacturers may use a mixture of Argon and Krypton. You might even find Zenon and Nitrogen in rare instances.
Spacer Types: The spacer between the glass panes is critical to the performance of the insulated glass. There are a wide range of materials and shapes utilized as spacers such as an aluminum tube, a corrugated metal strip, a flat foam spacer, a roll formed spacer, or custom engineered stainless steel shapes such as the Endur XL Edge® corrugated stainless spacer.
Seal Types: A durable seal must be incorporated into the design to provide an airtight seal between the glass and the spacer. The seal creates a permanent barrier to keep the argon in and the moisture laden air out. The sealant types include Hot Melt Butyl, Polysulfide, Polyurethane, Polyisobutylene, Silicone, and Extrudable Polyurethane. A double seal combination of Polyisobutylene and silicone will minimize moisture permeation and maintain long-term adhesion for added life.
How Does It Work?