What Is Double Glazed Windows

by Matthew David | Updated: 09/15/2023

What Is Double Glazed Windows

Have you ever gazed longingly out your drafty, fogged up windows on a cold winter day and thought there must be a better way? My friend, there is – and it’s called double glazed windows!

These ingenious inventions have been around for decades, but many homeowners still don’t understand how they work or why they’re so great. Well, grab a warm cup of cocoa and get cozy while I explain everything you need to know about double glazed windows!

How Do Double Glazed Windows Work?

The magic of double glazed windows lies in their construction. Unlike regular single paned windows that have just one sheet of glass, double glazed windows have two panes of glass separated by a gap.

This gap is enclosed in a frame, creating a sealed unit that’s filled with gas and is known as an insulating glass unit (IGU). It’s kind of like a glass sandwich – the bread is the panes of glass and the filling is the gas!

Between the two panes is a spacer bar that separates them at a set width, usually around 6 to 12mm. The gap is filled with a heavy insulating gas like argon, krypton, or xenon. This slows down the transfer of heat and cold through the window.

Some double glazed windows also have a low-emissivity (Low-E) coating on one or more of the panes. This helps reflect heat back into the room in winter and reflect the sun’s heat away from the room in summer. Pretty nifty!

So in a nutshell, double glazed windows create a thermal cushion between the interior and exterior. This slows down the conduction and convection of heat and cold, helping maintain a comfortable temperature in your home.

Benefits of Double Glazed Windows

There are so many great benefits to installing double glazed windows in your home. Let’s look at the top few:

Energy Efficiency

The number one benefit is the boost in energy efficiency. By slowing heat transfer, double glazing reduces how much warm air escapes in winter and how much heat radiates in during summer. This means you’ll use less energy for heating and cooling!

Over the lifetime of a double glazed window, you can save hundreds of dollars on utility bills. And reducing your energy usage is also great for the environment. It’s a win-win!

Noise Reduction

Double glazed windows are excellent at damping noise. The air gap and glass combination help block lower frequency sounds like traffic or noisy neighbors. For even better sound proofing, specialized laminated glass with inner vinyl layers can absorb up to 35% more sound.

If you live on a busy road or have loud surroundings, noise reducing double glazing could make a world of difference in keeping outside noise where it belongs – outside! You’ll enjoy peaceful, quiet ambience indoors.

Less Condensation

Ever dealt with annoying condensation on your windows on cold mornings? The inner pane of glass in double glazing stays closer to room temperature and avoids that cold surface where moisture condenses. This means minimal window condensation.

The insulating glass unit also has desiccant inside the frame to absorb any moisture in the air gap. This prevents fogging inside the glass and keeps your view crystal clear.

Enhanced Comfort

With reduced drafts, lower noise, and no window condensation, double glazing creates a noticeably more comfortable environment indoors.

Rooms feel warmer in winter, cooler in summer, and you don’t get that chilly feeling sitting near the window! It’s amazing what a difference high performance windows make.

Types of Double Glazed Window Frames

The glass sealed unit inserts into a frame to create the complete double glazed window. There are a few common options when it comes to frame material:

uPVC Frames

uPVC (unplasticized polyvinyl chloride) is the most popular choice for double glazing. It’s a durable plastic polymer that’s resistant to weathering and wear.

uPVC frames have sleek corner welds and come in many colors and finishes – from simple white to realistic wood grains. They provide excellent thermal performance for energy savings.

Aluminum Frames

With narrow frames and seamless designs, aluminum gives a sleek contemporary look. These lightweight frames come in various powder coated colors and resist rusting or chipping over their lifetime.

Aluminum isn’t quite as insulating as other materials but is great for larger expanses of glass and for making a stylish statement.

Timber Frames

For a traditional touch, timber framed double glazing looks beautiful on period style homes. Premium laminated softwoods like oak resist swelling and rotting. With proper maintenance, timber frames can last over 60 years!

Timber isn’t as insulating as uPVC or composite materials. But if aesthetics are your main priority, timber double glazed windows add charm and authenticity.

How Are Double Glazed Windows Made?

To understand why quality matters so much, let’s look at how double glazed windows are manufactured:

The glass sealed unit is first assembled in a climate-controlled environment. An automated robotic arm picks up the glass panes to avoid any defects or cracks from handling.

The panes are pressed together with the spacer bar frame between them. This assembly then moves into an airtight argon gas-filled chamber. As the unit passes through, the air is flushed out and replaced completely with argon.

Next, the unit is permanently sealed all the way around with heat-cured sealant. The desiccant to control moisture is inside the spacer bar. The sealed argon-filled unit is now ready for mounting.

The sealed unit is carefully inserted into the uPVC, aluminum, or timber window frame. It’s glazed into place with a silicone or acrylic sealant for weatherproofing.

Finally, the complete double glazed windows are rigorously tested to ensure there are no leaks or defects before installation.

When manufactured using automated precision, quality control, and rigorous testing, it results in robust double glazed windows that will perform for decades.

Double vs. Triple Glazed Windows

Triple glazed windows take it up another notch by having three panes of glass instead of two. They provide even better thermal insulation with R-values between 4 to 7.

Triple glazing is recommended for very cold or extreme climates to maximize energy savings. Some situations where triple glazing makes sense:

The downside is triple glazing comes at a higher cost. The extra weight also makes windows less stable and more difficult to open.

For moderate climates like the UK, quality double glazing hits the sweet spot of ideal energy efficiency and affordability for most homes.

Improving Your Existing Double Glazing

If you already have double glazed windows that are losing their edge, there are DIY ways to upgrade them:

With a few upgrades, you can enjoy the prime efficiency double glazing provides for many more years before needing full replacement windows.

Double Glazed vs Single Glazed Windows

Compared to old drafty single glazed windows with just one pane of glass, double glazing is a veritable superhero!

Single glazing offers minimal insulation and energy efficiency. It also readily allows noise and humidity to pass through. Your home needs double glazing to defend against external forces!

In fact, UK building regulations now mandate that replacement windows must be a minimum double glazed specification. Double glazing is the new normal when it comes to energy efficient windows.


I hope this has helped explain what double glazed windows are and why they’re amazingly effective at insulating your home.

With double glazing, you’ll enjoy lower energy bills, reduced noise and condensation, improved comfort – all while doing your part for sustainability. It’s an upgrade that pays dividends for years to come.

So next time you gaze out your window, picture the cozy comfort double glazing provides in every season. Stay warm my friends!