Double vs Triple Glazing? What is triple glazing and is it worth the extra money?

If you are considering getting new windows everyone will consider if they should consider triple glazing over the more affordable secondary glazing.

As the name indicates triple glazing contains three panes of glass within a sealed frame, just as double glazing contains two. Between each pane is a pocket of air or inert gas, such as argon; argon is heavier than air and works as an insulator for both noise and heat.

This, therefore, makes a triple glazed a superior solution for both insulation and reducing noise. But will pay for itself through saved energy bills?

Windows energy efficiency performance is measured in a U value.

• Single glazed windows have a U value in excess of 5
• Double glazed windows used to score over 3 but as a result of improvements in the manufacturing process (more below), Building Regulations insist that any window you install today should have a U value no worse than 1.6
• The Passivhaus standard requires triple glazed windows with a U value of no more than 0.8 but there are some suppliers who claim to achieve just 0.5

In comparison, the minimum value an outer wall can be is 0.3, so your windows will always be the weak spot for insulation.

What this means is that the surface temperature of a modern, energy-efficient double glazed window is 16°C in a room heated to 21°C where triple glazed can offer 18°C.

The nature of triple glazing can also help reduce condensation, and if this is something you suffer from it is definitely worth considering when switching from single glazing.

To improve sound reduction and reduce condensation, it could also be worth considering the more affordable secondary glazing.

Triple glazing should offer superior sound performance, but this is not always the case, low-quality glazing can sometimes be worse than double. For example a 36mm thick triple glazed unit may not perform quite as well as the 36mm double glazed counterpart, however, the U value will still be superior.

For people living in cities, or very busy roads, triple glazing can offer superior noise cancellation but this often requires a very think unit.

If you already have existing double glazing then the saving gained from triple glazing probably are not worth it, however for new builds or moving from single to triple then they are certainly worth considering.