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Triple Glazing

Triple glazing has been widely used in Scandinavian countries for many years, mainly on account of adverse weather conditions; but has remained a small market within the UK compared to double glazing.

With government initiatives driving towards zero carbon homes by 2016, triple glazed windows are becoming a much more popular choice as a form of energy reduction in modern houses.

Many in the industry believe that triple glazing is set to take much larger market share in the coming years, but the question for consumers is whether it is that much more cost effective, and whether the energy savings make the investment worthwhile.


What is triple glazing?

Illustration showing section through a triple glazed window

Section through triple glazed window

Quite simply triple glazing is the addition of an extra pane of glass, so that instead of two panes of glass, there are three – which reduces heat loss considerably when compared with double glazing.

Disadvantages are that triple glazed windows are heavier than double glazed units, and in some cases may actually reduce heat absorption because of the extra pane. They are also significantly more expensive, with the most efficient products using Krypton instead of Argon to fill the cavities.


What are the benefits?

The advantages are the energy savings, due to the lower U value, and better noise reduction. The energy savings are not as substantial as you might expect when compared with good quality double glazed units, but there is no doubt that triple glazing is more efficient. Triple glazed windows also offer superior noise reduction, so they are a good option for windows overlooking busy roads and noisy areas.

With government targets expected to demand even lower U values, many glazing manufacturers believe that windows with a WER rating of A will be a requirement at some point in the near future.

St Gobain, for example, stated that they intend to produce A rated windows as standard across their range by 2016, and they expect triple glazing to make up around 30% of the market. The advantage is that it will be able to meet the most stringent of targets; and it may become a necessity rather than a choice.

One of the key benefits is the comfort factor. It is difficult to put a value upon and ultimately depends on the individual, but it does help the house retain heat better, and the difference is noticeable within the property.

The PassivHaus institute in Germany illustrated this in a series of tests measuring the surface temperature of the glass in cold weather, with room temperature set at 21°C. The double glazed window had a surface temperature of 16°C, compared to the triple glazed window which had a temperature of 18°C.


What effect does it have on U value and energy efficiency?

In Europe the low energy PassivHaus standard requires windows to have a U value of 0.8, and it is thought that the UK targets may fall in line with this standard in the coming years. Building regulations currently demand windows have a U value of 1.6 and the most energy efficient double glazing units conform to this requirement.

Cross section through triple glazed window

Cross section through triple glazed window

The move towards low carbon homes will look at windows as one of the targets for reducing heat loss; in comparison walls have a maximum U value of 0.3, so it is to be expected that triple glazing will become more popular due to energy efficiency requirements.

Europe tends to lead the way in the energy efficiency in glazing, and Germany in particular is commonly seen as an indicator of the future of the UK market, as we have historically followed their lead by 5-10 years.

Since developing triple glazing, Germany has seen it grow from just a 3% market share to 37% in the space of five years. If the UK follows suit, we can expect a similar level of growth in the next five years.


What are the extra costs and the long term savings?

While triple glazed units may become more widespread in new buildings in the future, the replacement market is a different proposition and consumers should think carefully before opting for that extra pain of glass. It can cost anywhere between 30-50% more than double glazing and may not provide sufficient savings to justify the initial outlay.

The payback period must also be considered, as any savings will be spread out over several years. It’s worth finding out the life expectancy of the windows before buying them, and comparing the potential saving against that of double glazed units.

The other, less tangible, factors to consider are the additional benefits, and how these affect your perception of the value of the windows. If you live by a major road the extra cost may be justifiable because of the improved noise reduction. While the extra comfort afforded by the higher surface temperature maintained by triple glazed windows will appeal to others.



Triple glazing is not new to the UK, but up to now it has always been very much a niche market within the windows industry. With such an emphasis developing on more energy efficient and low carbon homes, it is likely to see a boom in the next few years as a result of stricter building regulations.

The windows are superior to double glazing in several respects; they are more energy efficient and therefore have a lower U value. They decrease noise and provide a greater level of comfort within the home as triple glazing holds heat that much better. Double glazing still provides an adequate level of efficiency, and triple glazed windows will not overtake double glazing in the replacement market in the foreseeable future.

As a consumer the initial desire is to buy the most energy efficient product we can find, but more consideration needs to be given to whether triple glazing is right for your property.

Will there be enough of an energy saving to justify the costs of buying the windows? How long will the payback period be to make the windows cheaper than the double glazed alternative? Although triple glazing is the most energy efficient type of window available today, it is not necessarily the best choice for everyone when all factors are considered.

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