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What is Double Glazing?

It’s quite simple: Two panes of glass are laid in a wood or plastic frame with an air or gas-filled space between them.

Although a double glazed window looks and functions no differently than a regular single glazed or single pane one, the key advantage is its insulating ability:

The air or gas between the panes of glass serves as an insulating layer that lets light through but also keeps heat in. By reducing heat loss, energy bills are lowered and a building’s overall energy efficiency is improved.


How it works

The basic physics behind double glazing is likewise quite simple. Glass is a very effective heat conductor, which means that on a cold winter’s day a single glazed window will allow much of the indoor heat out of your home.

girl looking at double glazed windows

What is double glazing?

Likewise, on a warm summer day a single-glazing will easily allow the outdoor heat to make its way indoors, quickly heating up the interior of a building.

Air and gas, however, are much less effective conductors of heat. The insulating layer of air or gas in the gap between the panes of glass stops the heat in its tracks, so to speak, keeping a home or office warm in winter and cool in summer. The difference in insulating ability compared to older single paned windows is dramatic and very noticeable.


Why it’s a popular choice

As the cost of energy rises, many homeowners in the UK find themselves looking for ways to reduce their heating bills. Heating a draughty home in the winter can be quite pricey, especially if the majority of the heat you are paying for escapes out of your single glazed windows. Heating the great outdoors isn’t a good deal for anyone!

Double glazing keeps more of that heat inside your home, reducing your energy bills. Though it does require an initial up-front investment, the money most homeowners save through lower energy bills and increased resale value of their homes can certainly offset this upfront cost.

The amount of time it takes to recoup your investment depends on the installation cost, your average energy use, and the amount of time you remain in the property. However, a home’s resale value increases right away as soon as the installation has been completed.

In addition to becoming more concerned about rising energy costs in recent years, more and more people in the UK are becoming aware of our common responsibility to protect the environment. Despite the North Sea Oil reserves, the UK depends on imported oil and gas to a large degree, and this, too, is a situation that many people are becoming uncomfortable with. For these reasons, not only can double glazing be an economical home improvement option, but it can also be a choice that fits well with the values and concerns of many UK citizens today.


Popular options

When considering a double glazing installation, UK homeowners have several options when it comes to the actual materials used. First, the space between the panes of glass can contain either air or an inert gas such as argon.

Cross section of double glazed uPVC window

Cross Section of uPVC Window

While both air and argon are good insulators, the advantage of argon is that it is a slightly more effective insulator than air. The difference is not dramatic, however. Argon-filled units are generally more expensive than air-filled ones, so budget considerations may also play a role in choosing which option to choose.

Second, frames can be made of aluminium, wood or uPVC (unplasticized polyvinyl chloride, a synthetic and lightweight building material). Each frame material has its own advantages and disadvantages, but due to its low cost and high durability uPVC is an increasingly popular choice.

Aluminium and uPVC frames do look more modern than traditional wood frames, so the overall style of your home and any heritage conservation rules you may be bound by can also influence your choice.


What’s involved in installation?

Home improvements can be relatively minor affairs, but they can also be disruptive and stressful. Although they may look forward to the end result, few homeowners relish the thought of workmen trooping in and out of their homes, tracking dust over the rugs or interrupting one’s everyday routines. A common concern many homeowners have is the level of inconvenience an installation will cause.

The good news is that installations are relatively unobtrusive. The average installation takes from one to three days and involves measuring your windows, removing your old ones (and fittings), and installing new frames. Compared to, for example, having a new roof fitted, the installation process is quite efficient and quiet.


Choosing a double glazing company

In recent years, the number of companies fitting double glazing in the UK has increased dramatically. The market is now quite competitive, which means that homeowners considering an installation can usually shop around among a number of firms for the best price.

That being said, the decision on which company to hire should not be made on price alone – homeowners should also consider a firm’s reputation, experience, after-installation service, and willingness to guarantee their work. In addition, reputable contractors will almost always be registered with industry associations. Always ask the companies you are considering for their registration and accreditation information.


The cost of double glazing

The cost of installation depends, among other things, on the size of your home and the number of windows you are considering replacing. Keep in mind that it is not necessary to replace all of them at one time. You may consider installing double glazing on one floor only, or even in just one room.

You’ll find lots more information on paying for your new windows in our Finance section.



Hopefully this article has served as a useful introduction to the subject, and given an insight into how it works and why it is one of the UK’s most popular home improvements. The rest of this site will go into more depth on the various aspects of double glazing that you need to understand before making a purchase.

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