What are triple-glazed windows and why they are worth using

Choosing the right glazing is a big investment in a residential building. So if you're considering triple glazed windows, here's our advice on deciding if they're worth it.

What are triple-glazed windows

In short, what may seem obvious, triple glazing contain three panes of glass in a sealed frame. Similarly, double glazing contains two. Between each panel is a pocket of air or an inert gas such as argon. Argon is heavier than air and acts as an insulator of noise and heat. A third sheet of glass placed halfway between the inner and outer panes of double glazing creates two airlocks. Which improves the energy efficiency of ordinary double glazing by about 50%. Energy efficiency further improve variables such as the type of air or gas used in the cavity, warm distance frames on the perimeter to reduce thermal bridging and various coatings on the glass to reduce energy loss from the inside. The frames themselves also have a major impact on overall performance (as well as insulation). Pay attention to energy-efficient frames, which have a good leakage rating.  

Why invest in triple glazed windows? Double or triple glazed windows which is better?

Because triple glazing have three panes of glass in an airtight frame, the windows provide better energy efficiency than double-glazed windows. In fact triple glazing can reduce heat loss by approximately 30% compared to double glazing, so energy savings are significantly higher, which means thatheating bills will be lower. Thermal transmittance double-glazed windows is for Ug = 1.1. In contrast, for windows triple glazed Ug = 0.5 Triple-glazed windows are therefore over 50 % warmer. The downside of triple-glazed windows is that they are more expensive. 

Triple-glazed windows are becoming an increasingly popular option among today's window suppliers - particularly in the aluminium space - but long-standing concerns among homeowners about the actual benefits outweighing the perceived costs remain.

Energy efficiency

A method of comparing the energy performance of windows is to use a U-value measurement, as we do with walls, floors and roofs.

Glass manufacturers have mastered the art of coating and tinting glass with various finishes that retain heat, protect against unwanted sunlight, reduce glare and are even self-cleaning. The net result of this glass engineering means that glazing U-values have been dramatically reduced.

Windows with single glazing can have a U-value of approximately 5.0 W/m²k
Double-glazed windows previously had a rating of over 3, but can now reach as high as 1.4 (Kommerling reaches 1.36). As a result of these improvements in the manufacturing process, building regulations now require every window you install today to have a U-value no worse than 1.6
The Passivhaus standard requires triple glazing with a U-value of no more than 0.8, but GM PLAST achieves 0.5
The U-value required for walls is currently less than 0.3, so it is apparent that windows remain weak points in the overall thermal efficiency of the building envelope. Hence, there is huge pressure to improve their performance even further.

Production improvements in glazing

Improvements have been brought about by the introduction of:

Wider recesses between two panes of glass 16 mm is the optimum distance
Low emissivity coatings are added to the glass to stop heat escaping
The cavity is filled with an inert gas, usually argon
Design of cold bridges, such as aluminium spacers, surrounding insulating glass units
Triple-glazed windows in the living room

GM PLAST offers triple glazing at a good price on all its windows. It is a specialist in the production of energy-efficient windows with low energy consumption

How much do triple-glazed windows cost?

Triple-glazed windows have long had a reputation for costing almost twice as much as double-glazed windows. Currently, the price difference is around 20 % between double glazing. The energy savings from replacing single glazing with double glazing are significant. The difference between a U-value of, say, 1.4 W/m²k (double glazing) and around 0.5 W/m²k (triple glazing) would be roughly 15-20%. It is therefore worth considering whether it is better to choose double or triple glazed windows in the long term.