The Advantages and Disadvantages of Triple Glazing

In the UK, double glazing has been the standard for window installation since it was introduced in the 1970s. Triple glazed windows only have a small percentage of the window market in the UK and do not have the same uptake that is seen in Europe and Scandinavia.

So, why hasn’t triple glazing had the same uptake, so far? We look at the advantages and disadvantages of triple glazing to see if they are the right option for you and if you might be missing out.

Advantages of triple glazing

Triple glazing has three panes instead of two for double glazing. The big difference between double and triple glazing is that the triple glazed unit has two air gaps, not just one, to reduce thermal transmission. Twice the air gaps of double glazed units and twice the buffer against cold air.

Superior thermal performance

The primary selling point of triple glazing is the superior energy efficiency. Standard double glazing windows have a WER rating of A, with A+ being the best rating on offer. Triple glazed windows achieve A++ rating for their efficiency.

The difference in U-values that measure heat transmittance represents how much more efficient having an extra pane of glass can be. Triple glazing is 24% more efficient with a Uw rating of 0.99 compared to 1.3 for the best double glazing. Upgrading from old double glazing to triple glazing can expect 60% more energy efficiency.

Building regulations currently require replacement windows to have a minimum U-value of 1.4 W/m2K. In the push to make housing more energy efficient to meet climate change targets, the U-value could be reduced again in the future.

Keeps heat in

In Scandinavia and parts of Europe, triple glazing has a market share of 60%. For cold weather climates and north facing windows, triple glazing is recommended to keep the cold air out and retain the warmth in a room.

Keeps heat out

Insulating air gaps between panes of glass not only keep cold air out, they can also help to keep rooms cooler in warm climates.

The G-value measures how much solar gain is transferred through a window. A higher number means that more solar gain can pass through and a lower number means that less solar radiation can pass and the room stays cooler.

Additional panes of glass in triple glazing reduce solar gain which means that less radiation from the sun is transferred into a room and can help to keep a room cooler.

Reduced condensation

Condensation forms on window panes when excess moisture in the air collides with cold surfaces. Windows are prone to condensation when it’s colder outside than inside.

Excessive condensation should not be ignored as it can result in harmful mould that is significantly bad for health.

To get rid of condensation, ventilation is needed. However, double glazing reduces thermal transmittance, so that the inner pane of glass is not as cold as the outside and moisture doesn’t form. Triple glazing can reduce the cold on the inner pane of glass even more with its super thermal efficiency, resulting in less condensation on the inside of windows.

Additional security

Because triple glazing has three panes of glass, it is more difficult to break through a window fully. This makes it more secure against intruders.

For the best protection, fusing a PVB layer into a pane of glass creates a laminated layer and this has the benefit of holding the glass together if it breaks. This is useful for glass in rooflights or for glass in doors and secluded windows that need extra protection.

Everest triple glazing has a toughened inner pane of glass with the option for a laminated glass pane in our triple glazed units.

Could increase property value

The focus on energy efficiency for housing in the UK means that there’s an emphasis on houses that have a high EPC rating.

All buildings in the UK are rated between G (lowest) and A (highest) as a measure of how energy efficient they are. An EPC certificate is required when renting or selling a property.

There is a proposal to introduce legislation that all rental properties be increased from E-rated to C-rated from 2023.

This emphasis on the higher EPC rating means that houses that are A, B or C rated will become more desirable for sale and potentially have more value.

Disadvantages of triple glazing

We look at the common misconceptions about triple glazing that have been perceived as 'disadvantages'.

The difference between U-values clearly demonstrates that triple glazing is a superior product in comparison to single and double glazed windows, especially for energy efficiency, and there are no real disadvantages.

In Northern European countries, triple glazing is the standard. At Everest, we want to drive change in the UK market to introduce more triple glazing and to offer homeowners the best possible products to insulate their homes.

Currently, most UK window companies have an older frame specification and cannot offer a triple glazing product comparable to the European market. We anticipate this to change in the next few years.

Because of this lack of investment, there has been negative debate about how effective triple glazing is for the UK market. Below we respond to these misconceptions about the ‘disadvantages’ of triple glazing.

Can we benefit in the UK?

Due to the considerably colder weather, in Scandinavian countries, triple glazing is the standard install. In the UK we have been replacing single glazed windows with double glazing since the 1970s.

It has been said that the efficiency of double glazing is effective enough against the climate in the UK - in comparison to the cold of Scandinavia.

However, triple glazing is superior for energy efficiency.

Standard double glazed windows have a WER rating of A, with A+ being the best rating on offer. Everest triple glazed windows achieve A++ rating for their efficiency.

Triple glazing is 24% more efficient than the best double glazing with a Uw rating of 0.99 compared to 1.3. Upgrading from old double glazing to Everest triple glazing can expect a 60% increase in energy efficiency according to the difference in U-values.

Is the extra cost worth it?

There are articles online that claim triple glazing is not cost effective enough for a mild climate in the UK. That might have been true several years ago when triple glazing was considerbaly more expensive, but Everest triple glazing is only 10%-20% more than double glazing.

Cost aside, there are many advantages of triple glazing and the cost comparison of two products shouldn't be the only factor to make inform a decision.

The additional comfort in a living space that can be achieved by installing triple glazing can increase the quality of life in the home alongside saving money on bills.

Extra weight of triple glazing

Glass is heavy and triple glazing weighs more than double or single glazing. That extra weight means that the frame and installation must fully support the difference.

Triple glazing is heavier due to the extra pane of glass - but a correctly specified window will only be built to a size that can carry the weight.  At Everest, we make sure we calculate the right glass sizes and have maximum sizes we can fit to.  We also fit heavy duty friction stays to support the extra weight of any opening windows. 

Extra thickness of the frame

Alongside the additional weight, the thickness of the window frame has to be considered for replacement windows.

The standard depth of a double glazed unit is 28mm and the standard size of a triple glazed unit is 36mm.

For some companies that extra depth on the triple glazed unit means that triple glazing cannot be fitted into their frame sizes.

Everest double and triple glazed units both fit into the same uPVC frame profile – this is because we have developed a thinner glazing bead to hold the wider sealed unit in place that is unobtrusive and very hard to spot.

Sound reduction is not as good as you would expect

You might think that three layers of glass are better than two for reducing noise, but, surprisingly, noise reducing double glazing is better. Standard triple glazing can experience vibrations on the internal pane to amplify sounds.

If noise pollution is important to you, we recommend our double glazing with noise reducing glass, which has been designed to be more efficient at reducing noise.

Double Glazing →

Our high-quality double glazed windows have an A+ energy rating – 1.3 W/m2K U-value

Triple Glazing →

Our triple glazed windows are our most energy-efficient, with an A++ energy rating – 0.80 W/m2K U-value