Double Glazing for Windows

Multi-glazing Elements for energy efficient Doors and Windows at Passive House Standards

The Different Types of Glazing

Generally, there are several options when it comes to choosing a glazing element for your door or window. All of these potential glazing elements can be installed into any frame, regardless of whether it is made from aluminium, uPVC or timber:

  • Single glazing
  • Double glazing
  • Triple glazing

As the names imply, these differ primarily in regards to the number of panes embedded in the frame. Among other things, this has a major influence on the overall thickness of a window or door and special attention needs to be paid when choosing the profile width to be able to fit the glazing element correctly.

However, the most important aspect here is - the higher number of panes, the better the casement or sash window's thermal insulation qualities become.

Relying on a single Pane

A single-pane glazing unit features only one pane embedded in the frame, and thus provides only severely limited thermal insulation. As heat transmittance is hindered only by a single layer of glazing, windows using this type of glazed element generally have a very high U-value of about 5 to 6 W/(m²K). Therefore, single-glazed units are considered to be severely out-dated and do not meet contemporary standards for insulation anymore.

Double-Pane Systems

Double glazing units are currently the most common choice for most homeowners. They are not as cheap as single panes, but their remarkable thermal insulation properties make up for the higher cost of the initial purchase.

A double-glazed system consists of a frame into which two panes are embedded. A spacer typically made of stainless steel, silicone or aluminium separates these individual panes from each other. The spacer does not only keep the panes at a fixed distance from each other, but also serves as a moisture barrier, preventing the interior of the glazing element from fogging up. However, most double-pane elements also feature an interior desiccant as well.

Even energy efficient double glazing loses much of its effectiveness if the frame itself is not insulated against thermal transmittance. A window literally is the sum of its constituent parts.

Without further improvements, the air pocket in-between the two individual panes decreases the thermal transference significantly. However, in order to reduce heat loss even more and achieve U-values that can meet passive house standards, the space is usually filled with a noble gas such as argon or krypton. These types of gas offer significantly lower heat conductivity than air, adding to the insulating effect of this type of glazing.

Modern double-glazed casement or sash windows can feature U-values lower than 1.2 W/(m²K), as long as the frame itself is also optimised to save energy.

Advanced Triple Pane Systems

Triple-glazed windows function based on the same principles as those with double-glazing elements. The difference lies with the third pane of glass and the resulting additional gas-filled space between the panes. These additions to the window can significantly improve its U-value to 0.8 W/(m⊃K) and below, but it also significantly increases the price of such windows compared to those of double-glazed variants. Thus, they are typically preferred in particularly cold areas of the world in which heating is necessary throughout the year. In such an environment, the additional insulation makes the cost associated with the third pane worthwhile.

Double or triple Glazing?

Certainly, the main points of contention when discussing the merits of double glazing compared to triple glazing are the prices and installation depths.

In moderate climates, a third pane of glass is often not imperative when it comes to providing exceptional thermal insulation. In such environments, choosing the more affordable double-glazed variant is entirely acceptable from an energy efficiency standpoint.

Additionally, triple glazing requires greater installation depth than double-pane units, typically leading to thicker windows overall. Particularly in older buildings, the thickness of the walls may simply not be enough to support a triple-glazed window.

Available Types of Glass for Double-Pane Windows

A window's properties are not only determined by the number of its panes - the characteristics of the glass itself also play an important role. The large variety of glass types available include:

  • Clear
  • Tinted
  • Ornamented
  • Tempered
  • Laminated

Naturally, the thickness of any of these types also determines some of its characteristics.


Clear glass is the standard transparent solution installed in most contemporary casement windows with double-glazing elements. Its main purpose is to provide an unimpeded view. However, it does require additional equipment such as roller shutters when it comes to protecting rooms against the rays of the sun as well.


Tinted panes are a solution aimed at reducing the effect of prolonged exposure to the sun. They heat up less than a clear pane and reliably prevent a significant portion of the sun's rays from entering your home. Of course, this can also prove to be a disadvantage, particularly in the less sunny winter months.


If you want to increase your privacy while also adding a certain something to the design of your home, ornamented glass can prove to be perfect for your needs. It is especially suited for bathroom or bedroom windows, as its structured surface allows sunlight to pass through unhindered yet also protects against prying eyes.


Tempered glass is mainly used for personal safety. Tempered glass panes are hardened by applying heat or chemical agents. While this slightly increases their robustness, the primary benefit is slightly different - When such panes break, they shatter into countless very small pieces, effectively preventing injuries as might be caused by larger shards.


Burglary protection is definitely an important point for any homeowner, especially in very remote areas. Panes made of laminated safety glass can make a burglar's task significantly more difficult. A special film within the pane itself presents a tear-resistant obstacle for burglars; even after the glass itself has been shattered. Most burglars are not willing to take the risk of using special tools and investing a lot of time trying to rip apart a foil scattered with glass shards.

Double-glazed Window Security

Apart from using laminated safety glass for burglary protection, installing additional security equipment for your double-glazed door or casement window can also be highly beneficial. This equipment includes, but is not limited to, security fittings such as mushroom cams lockable handles and advanced multi-point locking mechanisms as well as electronic alarm systems.

Tempered safety glass does not increase burglary protection significantly. Instead, to reduce the risk of injury, it is designed to shatter into a multitude of very small pieces upon impact.

Automatic electric roller shutters that are programmed to open or close under specific conditions add an additional layer of security. This is because most burglars make sure that nobody is at home before they act out their plans. Electric roller shutters can serve to pretend that somebody is at home, even when the house is actually empty.

Soundproofing a double-glazed Model

Naturally, protecting your home against outside noises is an equally important aspect of a double-glazed window's functionality. After all, constant exposure to noise can lead to health problems. Double-glazed windows are often filled with noise-cancelling resin that does not only block sound waves but also improves thermal insulation.

Design Options for double Glazing

Windows with double glazing elements offer many options for customisation. Not only can the material of the frame be chosen according to your specific needs, it can also be lacquered in a colour that matches your personal preferences. Furthermore, visual appearance is significantly impacted by what type of glazing is chosen. To achieve an especially elegant and sophisticated look, different kinds of glazing bars can be installed to turn your window into a unique piece of art. Windows and doors with double glazing can thus be matched to any house facade imaginable.

Thanks to the double panes, all available glazing bar options can be mounted to double-glazed elements.

Selection made easy - Get an online Quote for a double-glazed Window

Double glazing enhances your casement window in regards to thermal insulation, sound proofing and security and is thus a worthwhile investment. A comprehensive range of colours, decorative foils and materials for the frame facilitate in matching it to your personal aesthetic preferences. Determining the price of double-pane windows is also quite uncomplicated. If you can provide the dimensions necessary and have already chosen a frame material, glazing type and any additional equipment that you might require, most manufacturers can give a rather accurate quote of the estimated price even before your window or door is manufactured.

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