Composite windows explained by Glas Facades

Glas Facades' composite windows consist of an aluminium exterior and timber interior giving the strengths of hardwood and clean lines of metal, with low maintenance costs.

Darren Joyce of Glas Facades explains exactly what makes a composite window.

A composite window is basically one that's made up of more than one main element.

This means that specifiers, contractors and building owners get the benefits of both materials.

There are other types of composite windows available that offer very good thermal efficiencies and there are lots of permutations.

For example, steel can work very well as a window material because it ensures minimum sight lines and in a composite there can be a distinct thermal break between the inside and outside elements.

The main benefit of composite windows comes in low maintenance costs.

Since it is an engineered product the most weather resistant material can be used for the exterior.

Composite windows are highly engineered.

Even the wood is not just a length of timber that's shaped into a profile.

They are cut into planks that are laminated together and then the grains are matched so that they don't twist or warp.

Of course, there are some hardwoods that can be taken as a solid piece of tree trunk, shaped and treated.

Corner joints are CNC machined and there are approximately 20 different sizes and angles worked out to give the most strength.

Aesthetically, it just looks like a continuous piece of timber with a consistent finished grain.

One of the attractions of a composite window is that because there are separate elements it is possible to fit very large double or triple glass units.

As a result it is usually unnecessary to use expensive exotic gases (like Krypton and Xenon) and all the other expensive and cost prohibitive routes towards energy efficiency, since excellent efficiencies can be achieved with ordinary Argon.

We have even produced triple glazed windows with a combined U value of 0.7 W/m2K.

A steel window with a triple glazed sealed unit that had a centre pane U value of 0.5 W/m2K would probably have an overall U value of 1.2 or 1.3.

A highly engineered composite window can have a U value of 0.7 W/m2K using exactly the same sealed unit.

Acoustic properties can be improved by adding a third seal half way between the inner and the outer.

It is possible to use up to 40 mm sealed units and we can go in steps of 2 mm from 28 up to 40 mm with composites.

This allows us to purpose make the window system to suit the acoustic property to the building.

We can engineer the glass, even using acoustic laminates.

Thick panes or thin panes can be specified to cut down the acoustic travel through the window.

The acoustic qualities of an installation have certainly become one of the biggest factors, particularly for local authorities, though thermal efficiency also remains a key factor along with security and maintenance.

The cost of maintenance of public buildings can be prohibitive.

For example, when you have a multi storey building that has to be scaffolded when the windows need to be painted, that job must happen as infrequently as possible.

In these environmentally conscious times there is an increasing recognition of the need to provide construction material sourcing details and it is important to always state the area where the timber comes from: Eastern block; European hard woods; Canadian Pines or similar.

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