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Understanding Insulated Glass

On this page:
  • Anatomy and benefits of insulated glass
  • Air-filled and gas-filled IGU units
  • Types of insulated glass to choose from

What are Insulated Windows?

Chances are, if you are exploring a window replacement or renovation project, you have probably heard of the term “insulated glass.”. But, what exactly is insulated glass? And what factors should you consider when deciding between insulated glass — also referred to as double pane glass — and non-insulated glass?

Similar to other home renovation projects, opting for insulated glass is only part of the decision-making process when choosing new windows. Several different features and characteristics can be selected based on your needs, preferences, and budget.

Anatomy of Insulated Glass Windows

In its most basic form, an insulated glass unit, or IGU, is composed of two (or more) glass panes separated by a spacer, with air or gas filling the space between each pane. This space provides insulation from outside elements by limiting or stopping transfer of air from windows in and out of your homes. This helps your home stay warmer in the winter and cooler in the summer.

how insulated glass work and reduce heat loss - Modernize

For increased insulation (and cost), a third, or even fourth, layer of glass can be installed. However, regardless of the number of panes used, the core concept is the same — glass surfaces separated from each other and filled with air or gas.

Insulated windows can go a long way toward cutting household energy and utility costs, as well as adding to the aesthetic of your home. Continue reading to find out about different types of insulated windows and what insulated glass panels have to offer.

The Difference Between Gas and Air-Filled Windows

Something has to go in the space between your window panes, and while you might think it doesn’t matter, it absolutely does. Opting for air or one of several available gases will impact your window replacement project cost, the energy efficiency of the final product and the longevity of the renovation.

Air-Filled IGU

The first major decision is determining whether to use gas or air in your IGU. When filled with air, the seals that hold your window panes in place will have a longer lifespan compared to IGUs filled with gas. While this increased lifespan is minimal, it is certainly something to consider if you are looking for maximum longevity in your project. Air-filled IGUs also benefit from typically being the lowest-cost option when compared to gas. However, the low cost comes at a price.

Air-filled IGUs offer the lowest insulating value amongst double pane window options. As a result, they will be amongst the lowest rated insulated windows for energy efficiency. If you are looking to maximize your monthly energy savings, or have a home that is impacted by intense heat or cold, you might want to consider gas-filled IGUs.

Gas-Filled IGU

While air-filled IGUs will offer some levels of energy efficiency, this can be enhanced by filling the space between the panes with a gas such as argon, krypton, or xenon. These gasses  are denser than air and thus work to reduce the amount of air infiltration coming from outside and limit the amount of heat transfer through the IGU. 

As discussed earlier, gas is more prone to escaping an IGU than air, but at a loss rate of about 1% per year, many homeowners won’t notice an impact for decades. If you decide the boosted energy savings from gas is worth the added cost, you’ll have a few options.

The Benefits of Insulated Windows

When you purchase insulated windows for your home, you can benefit in numerous ways:

Energy Efficiency
First and foremost, insulated glass panels can increase the energy efficiency of your home because they prevent cold and hot air from leaking through them, which means your HVAC unit doesn’t have to work as hard. They have an average R rating of 7 and U factor between 0.15 and 0.18, both of which are standards for how much heat the glass retains and transfers. As a result, your energy bills can go down when you have these types of windows installed. You can read more about the optimum window ratings for energy efficiency here.
Noise Reduction
Loud music blasted by your neighbors’ teenagers or noises caused by planes overhead will not cause you as much aggravation when you have insulated windows. Since these windows block sound waves, they significantly reduce the amount of noise that comes into your home.
Return on Investment
If you are planning to replace your windows, insulated glass panels have a great return on investment. Not only do they help you save on energy bills, they also increase the value of your home, so you can obtain a higher price when it’s time to sell.

Types of Insulated Windows

Low-E Windows

Low-E windows, also known as low-emissivity windows, are coated with metallic material that is designed to reduce the amount of heat that comes through them—which can prevent a significant amount of energy loss. In addition to contributing to the energy efficiency of your home, these insulated glass panels can increase the longevity of your floors and furniture because they prevent them from succumbing to damage caused by the sun beating down on them all the time.

Tinted Glass Windows

Tinted glass windows have a film covering that can add to the look of your home while providing UV protection. Also, the film on these windows holds them solidly in place, which can protect them from being broken during natural disasters, as well as attempted burglaries.

Reflective Glass Windows

These windows have a thin layer of metallic coating on one side of the glass that can block UV light. Since they resemble mirrors, they can help with privacy because it is difficult to look inside of them during the daytime.

Double and Triple Insulated Windows 

Double insulated windows, often referred to as double-paned windows, have two panes of glass with a space between them that is filled with argon gas. Triple insulated windows, on the other hand, have three panes of glasses which make them even more energy efficient than double or single pane windows. The additional layer of glass provides an additional layer of protection from air leaking out the windows, and increases the level of privacy you enjoy.

Insulated Glass Installation Cost

When thinking of replacing your old windows, you can speak to your contractor about which insulated window glass would we a good options for you. The price of insulated glasses would we more than laminated glass. However, you will save more on energy bills with insulation than other glass type installations. You can expect to pay $375 to $1,000 for insulated glasses with additional cost for low-e coating.

There are also options available for using a combination of different glass types. Manufacturers now offer strengthened glass types with insulated and low-e coating for best performance. Use our guide for window glass replacement costs to see prices for difference glass types before you make a decision.

Find an Experienced Contractor 

If you need help finding an experienced contractor for your window installation, look no further. The pros at Modernize can connect you with experienced, local contractors who will help you choose the best type of insulated glass panels for your home and complete the installation. To assist you, we have created a Contractor Checklist as a simple, step-by-step guide for finding the right professional for your windows project.