Window glazing guide

Window glazing plays an important role in the energy efficiency of your windows, as well as in security, safety and privacy.

Read our window glazing guide to learn about the most efficient glazing, the benefits of triple glazing, and features to look out for.

What is window glazing?

Window glazing is the glass element of a window. It is commonly used to describe how many layers of glass are in a window (eg. single pane or triple pane) or it can also mean the process of installing new window glass.

‘Insulated glazing unit’ (IGU) describes glazing with two or more panes separated by space to improve the insulation, such as in double or triple glazing.

Good window glazing helps to insulate a building effectively, saving money on energy costs and reducing CO2 emissions.


Dakea window in a bedroom


What are the different types of window glazing?

The different types of window glazing may include the following:

  • Triple glazing (three pane)
  • Double glazing (two pane)
  • Single glazing (one pane)
  • Tempered glass
  • Laminated glass
  • Low-e glazing

Single, double and triple glazing describe the number of panes that are in a window. Single glazing has only one pane of glass, while triple glazing has three. In double and triple glazing, there is a layer of gas between the panes that contributes to the thermal efficiency of the window.

Single glazing

Single glazing is rarely available on the market as it provides poor insulation, poor safety features and will decrease the overall energy efficiency of your window. It’s prone to issues with condensation.


It was once the only variety of glazing available. When double glazing was invented, some people still chose single glazing as a lower cost option. However, the lower initial cost of the glazing is heavily outweighed by the increased cost of keeping the building warm!


Single glazing windows can also negatively impact a building sale value.


Therefore, windows now are usually only available in either double glazing or triple glazing.

Triple glazing benefits

Triple glazing has a number of benefits over double glazing:

Increased thermal efficiency

Three panes, each with a layer of gas between, means triple glazed windows are more insulative than double glazed. It’s harder for heat to escape in winter, and heat to enter in summer.

Improved thermal efficiency keeps heating bills down.

Noise reduction

Second to thermal efficiency, noise reduction is one of the most popular reasons for choosing a triple glazing window. Particularly helpful for houses built on busy roads, for example, the three panes make it more difficult for sound to pass through the glass when the window is closed.

Condensation reduction

While triple glazed windows can still suffer from condensation, the improved thermal efficiency reduces the risk. It helps to keep the internal temperature up, so moisture in the air is less likely to condense on the glass.

Find out more about stopping window condensation in our blog.

Added security

With three layers of glass, triple glazed windows are harder to break. This makes a home more secure.

This is especially helpful when paired with laminated glazing, which you can learn more about below.

Read our roof window security tips if you’re looking for a roof window that provides the best security.

Added sale value

Homes or buildings with triple glazing can often be put on the market for a higher price – or simply have increased curb appeal to make a good sale more likely.

Disadvantages of triple glazing

The disadvantages of triple glazing are:

  • More expensive than double glazing
  • They are heavier, so will require purpose-built window frames

For many people, the benefits of triple glazing outweigh the drawbacks, but if cost is a significant factor, double glazing can provide a viable alternative if the regulatory requirements (eg. U-value) can be still achieved.

Laminated Glazing

Laminated glazing is a type of safety glass that has a thin polymer layer that keeps the glass together if it breaks. It reduces the risk of injury from shattered glass and adds security.
Someone attempting to break a window to gain entry to a building cannot do so.

Cracked laminated glass


Laminated glazing can be combined with double or triple glazing. Our Ultima Energy windows, for example, feature laminated triple glazing while our security roof windows include an improved laminated double glazing.

Toughened glass

Toughened glass, or toughened glazing, is glass that has been heated and cooled to specific temperatures in order to strengthen it. It’s sometimes called tempered glass. It’s up to five times stronger than ordinary glazing.

It’s an important safety feature that helps to reduce window breakages and can provide additional security.

All our roof windows at Dakea include toughened glazing.

Window glazing gas types

In double or triple glazing, there is a layer of trapped gas between each of the panes, known as the glazing cavity. This provides an insulating layer that improves the energy efficiency of the window.

There are four types of gas used in window glazing: dehydrated air, and inert gases which are argon, krypton and xenon.

Dehydrated air

Initially, when double glazing was first invented, manufacturers used dehydrated air in the cavity. This is air that has had the moisture removed, which means it has a higher thermal efficiency than standard air. However, you rarely find this in modern window glazing options. Compared to inert gases, it’s significantly less effective.


Argon is a form of inert gas – meaning it doesn’t undergo a chemical reaction when conditions change, such as temperature. The thermal conductivity of Argon is 33% better than air. It is very common in double and triple glazed windows as it’s relatively inexpensive, while still having good insulative qualities.


Krypton is even more effective than argon, although more expensive. The insulative effect of krypton is 40% better than argon and 65% better than air.

It’s a denser gas, meaning that as heat comes into contact with it, it’s more difficult for the molecules to interact. Therefore, it reduces heat loss through the window. Like argon, it’s commonly found in domestic windows. Windows that use krypton will be highly insulative and provide some of the best energy efficiency.


Xenon is not commonly used in domestic window glazing, but it is sometimes used in commercial or industrial windows designed for speciality applications.

It is extremely dense, but is also extremely expensive.

What to look out for

When it comes to window glazing, you should ensure your double or triple glazed windows either use argon or krypton. If you’re on a tight budget, opt for argon gas as this will keep the cost down while still providing good thermal insulation.

If you’re looking for a highly efficient window, look for one that uses krypton as the cavity gas. This is the most thermal efficient choice for your glazing. It will help to keep energy bills down and reduce CO2 emissions.


Window glazing energy ratings

There are other metrics that can be used to measure the energy rating of a window and its glazing, but the most commonly used is u-value.


U-value defines how much heat is lost through the glazing, sometimes known as the heat transfer coefficient, or thermal transmittance coefficient. The lower the U-value, the more energy efficient a window is.

Ug is the U-value of the pane specifically. Uw is the U-value of the window as a whole.

At Dakea, the Ultima Energy roof window has our lowest Ug value at 0.5 W/m2 K.


Dakea’s window glazing options

Window range Glazing type Gas Ug (W/m2 K)
Ultima Energy roof windows Triple, toughened, laminated Krypton 0.5
Azure flat roof windows Double, toughened, laminated Krypton 1.3 (horizontal)
Good roof windows Double, toughened Argon 1.0
Optima roof windows Double, toughened, laminated Argon 1.0
Better Energy roof windows Triple, toughened Argon 0.77
Better Safe roof windows Double, toughened, laminated Argon 1.0
Secure White roof window Double, toughened, laminated* Argon 1.0

* This includes 4 tear-resistant foil layers for improved safety and security

Interested in a window? Get in touch and request a quote. We’d be happy to help.

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