Window Replacement: Insulated Glass Unit (IGU) Explained

You just went to a window replacement company, and the salesperson is talking about insulated glass units (IGUs). You are familiar with replacement windows, but the glass is something that you have never heard before. You are wondering what all the fuss is about. Well, this article explains the insulated glass units (IGUs) and what it means, as well as its components.

Windows have a component called the insulated glass unit (IGU). The IGU is a double or triple-paned window with air or various gasses sealed between the panes. Argon and krypton are two of these gasses. The IGU is a great option for homeowners that are looking to improve the energy efficiency of their home by decreasing heat transfer through their windows.

What is an Insulated glass unit?

The name sounds complicated and technical, but it is a simple concept: two or more panes of glass with air or gas in between them. The most common IGU has two panes of glass with air space in between them, but there are other combinations.

An IGU forms a sealed unit. You cannot open it. The insulating effect depends on the type of gas used and the thickness of the gap between the panes of glass. Both of these factors determine how much heat will transfer through the glass.

Components that make IGU

There are three main components that are required to make an insulated glass unit (IGU).

  1. A sealed air space between two or more panes of glass
  2. A spacer system to maintain a constant air space
  3. A sealant to hold the above components in place

The combination of the above three components will help you achieve the best possible performance in your window replacement insulated glass unit.

Why choose an insulated glass unit (IGU)?

Insulated glass units provide an extra layer of protection from the elements, increasing your home’s energy efficiency. Homeowners can save on their monthly utility bills, as well as help protect our ozone layer by reducing greenhouse gas emissions.

IGUs also create a buffer between the outdoors and indoors, providing improved comfort from temperature fluctuations. And because the airspace in an IGU acts as an effective sound barrier against outside noise, you can also enjoy a quieter home. The better insulated your windows are, the less you’ll hear traffic, lawn mowers and barking dogs.

How does an Insulated Glass Unit (IGU) work?

A window built with insulated glass technology has two or more panes of glass separated by a “spacer” (this is the metal/aluminum that separates the two pieces of glass). The spacer contains desiccant (a drying agent) that absorbs any moisture that may exist between the layers of glass. This moisture would normally cause the space between the panes to fog up and obscure your view, but thanks to this technology, it won’t happen. This is the reason why a window built with insulated glass technology will never fog up or lose its seal.


All in all, insulated glass is a great way to increase the energy efficiency of your home. Not only are you saving money on your energy bill, but you’re also saving the earth by decreasing your carbon footprint. IGU units are a great way to go green and help the environment in the process. IGU unit is one of the most important factors to consider in any window replacement project.

Orlando Loyal
the authorOrlando Loyal