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Double glazed units and triple glazing

Triple and double glazed.jpg

If triple glazing is so good why aren’t the triple glazed units fitted to every window?

Normally it’s a sales person or manufacturer that is telling you that the triple glazing is so much better because they can charge you more for it!

The reality is that poor quality triple glazing can be worse than a double glazed unit. This means that the true answer to “which is better, double or triple glazing?” is very complicated.

Generally people are considering the thermal and noise benefits of the glazing when they are asking about triple glazed units. It may seem a little strange, but it is the argon filled gap that provides the main benefit not the glass.

Double glazed units started at 20mm with 4mm glass 12mm gap and 4mm glass. This was changed to 24mm which had a 4 + 16 + 4 combination. Modern DGU (double glazed units) are 28 mm. (4 + 20 + 4).

If you are looking at triple glazing that is 28mm wide you end up with 4 + 8 + 4 + 8 + 4 – this is going to be less efficient that the double glazed unit.

To get the full benefit of triple glazing you should be looking at 44mm units. This is 4 + 16 + 4 + 16 + 4.

Full, quality triple glazed units can improve the thermal efficiency by 20 – 30%. This shifts an A+ double glazed unit to A++ triple glazed unit. The U value of a double glazed unit is around 1.3 this is lowered to 1 with triple glazing. Another benefit of triple glazing is that triple glazing can reduce the amount of condensation.

Why should you consider triple glazing?

Triple glazing is a lot more expensive than double glazing. It is a sensible choice if it reduces your bills by more than the difference between the double glazed units. Calculations should by done over a twenty year period.

It should also be considered if it offers you environmental benefits – such as reduced noise levels.

If you are next to a school and want to reduce the noise then you may want to consider triple glazing. Exposed properties with north facing windows would also benefit from triple glazing.

Please note that if you have a property with 20mm double glazing you will really notice a difference with 28mm units. However, this would mean replacing the frames in most cases.

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