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Everything you need to know before buying Windows, Doors or a Conservatory

Triple Glazing / Triple Glazed Windows

What are the Pros, Cons and costs of Triple Glazing over regular double glazed windows

What is Triple Glazing

As you have properly worked out triple glazing is the same concept as double glazing but with three panes of glass instead of two.  The process of creating a double glazing unit invoices the sealing of 2 panes hermitically sealed with air or some sort of gas. Triple glazing uses the same process but sandwiched a third pane between the inner and outer pane of glass.

Any form of glazing is designed to stop the heat loss for a property whilst being able to see through it and let light into a room. As the majority of heat escapes though windows and the every increasing cost of energy it makes sense to look at all possibilities to cut heat loss.

In theory adding a third pane of glass is a logical way of increasing the performance of the glass and cut down in the loss of heat through a windows but like most things it is not a straight forward as increase the effectiveness by 1/3, there are some problems with scaling up to triple glazing and should be very careful considered before choosing triple glazed windows.

Benefits of Triple Glazed Windows

Before we look at the benefits of triple glazing first you have to understand how the glass in windows links in with the energy efficiency of a property. Firstly there is direct heat loss, normally measured in U Values and is basically the loss of heat over a particular area measures in time. The slower the heat escapes the better. In recent years glass manufactures have achieved better results with Low-E (Low Emissivity) Glass such as Pilkington K Glass or Saint Gobains Planitherm, which is a coating to stop energy escaping.

Adding another pane of Low-E glass defiantly helps the U Value of a window and adds a barrier to heat escaping out of a room. however the u-value is only one measure used in the rating system for energy efficient windows.  It can lower the u-value from 1.6 in a double glazed window to as little as 0.8 in a triple glazed window.

On of the other major advantages of triple glazing is the noise reduction adding another physical layer of glass can cut the noise by 1/3 however there are acoustic solutions with glass that are far more effective is that is a real problem, such as 10mm and 6mm glass combinations designed to filter out different frequencies. 

The science of has be

Single Glazed

Pre k glass Double Glazing

C rated Double Glazing

Triple Glazing





en tested quite extensively in Germany, below are the results. with a OC outside and 21C inside



Disadvantages of a Triple glazed Window?

Triple glazing may stop heat escaping but this in only one third of the measure for a A rated windows. Another third comes from Solar gain. Solar gain is the free energy from the sun heating up the property on days where is may not be warm but the the sun in shining. Adding a third pane of glass can decrease the solar gain into a room and has an adverse effect on the energy rating of a window.

Technical issues with triple glazing

All of the advantages and disadvantages of triple glazing are ok in theory but they assume that adding another pane of glass is technically possible. Well it is not always technically possible as using a 28mm double glazing uses the make up of 4mm glass / 20mm gap / 4mm glass. triple glazing has to be either 4mm glass / 6mm gap / 4mm glass / 6mm glass / 4mm glass and can get quite fiddle.  The preferred method is to use 32mm units however most double glazing systems of not designed for 32mm units and involves as special glazing bead which as thin and can look ugly.

The other big problem and the weight, glass can be very heavy adding another layer with make windows very heavy so the windows will need upgraded hardware and heavy duty hinges and still may drop or be difficult to open and close.

Cost of Triple Glazing

Because triple glazing is quite a specialist product, low volumes and the upgrade in the hardware required I have seem triple glazing cost as much as double that of double glazed windows, so make sure it is something you really want.

Double VS triple Glazing

Triple glazing can have its uses however in my option the advantages in recent years in Low-e and low Iron glass you can achieve just a good results with high quality A rated double glazed windows that you can with triple glazed windows without all the other associated problems. However a think we will see more testing a R&D in upcoming years that will combine different glass and spacer bars with specially designed triple glazed window profiles to product some very good results so watch this space.


Q: Can you get wooden or aluminum windows with triple glazing

A : Generally yes with there is enough space to glaze in the windows, also because wood and aluminum is more structural there are less technically problems with triple glazed Aluminum of Triple glazed wooden windows


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