Triple Glazing Vs Double Glazing


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Double Glazing Vs Triple Glazing

What is the difference between double glazing and triple glazing windows and which is the better option for your home? We carried out an experiment to demonstrate which type of glazing is better.

Triple glazing vs Double Glazing

Having new windows installed is an event you would expect to do only every 30 years or more. So it’s important to make the right decision for your needs when choosing between double glazing or triple glazing for your windows.

To help you make the right choice, we have highlighted the main differences between double and triple glazing.

What is the difference between double and triple glazing?

Double glazing is a sealed glazed unit that has two panes of glass and triple glazing has three panes of glass. The panes of glass used in each unit do not need to be the same and by using different types of glass you can have windows for different needs.

At Everest, we can construct your glazing bespoke to your needs, such as:

  • Heat retention - a low e coated glass pane
  • Noise reduction - our specialist 6.8mm laminated glass
  • Privacy - an obscure frosted pane of glass
  • Security - a 6.4mm laminated pane of glass

Although double and triple glazing can use the same types of glass and have many similarities, the main differences are between the enhanced performance and efficiency:

Heat retention

Double glazing works by having an air gap that reduces the thermal transmission of hot and cold air.

Having an additional pane of glass in triple glazing creates another air gap to increase the efficiency of heat loss or solar gain. Effectively, it’s a double, double glazing unit.

Noise reduction

Although standard triple glazing can dampen noise when replacing single glazing, the middle pane of glass can actually increase sound vibration and amplify sound transference. For the best results in sound reduction, a glazed unit needs to disrupt the soundwaves transmitted through the glazed unit. This can be achieved by adding a pane of glass with a specialist laminated layer.

However, if you have more than average noise levels, we recommend that you will need to make other changes to your house to get the best results of noise reduction.


Laminated glass has a polyvinyl butyral (PVB) layer of thin plastic between two panes of glass. If laminated glass should break, the glass is fused to the PVB layer and stays in place. For this reason, it’s used in skylights or glass ceilings to avoid glass shattering and falling from above.

Adding a layer of laminated glass to a glazed unit will make it more difficult for an intruder as the PVB layer makes it harder to break open.

Triple glazing also has an additional pane of glass making it even more difficult to break than standard double glazing.

Depth of frames

One important point of difference between double and triple glazing is the depth of the glazing units, making it a problem for fitting in existing windows. The standard width of a double glazed unit is 28mm and the standard size of a triple glazed unit is 36mm. That extra depth on the triple glazed unit means that triple glazing cannot always be retrofitted to existing frames.

Thinking About New Triple-Glazed Windows?

Benefit from a warmer, more energy-efficient home.

Double glazing vs triple glazing comparison

Double glazingTriple glazing
Highest Energy ratingA+A++
Lowest U Value (heat transfer)1.220.80
G Value (solar gain)0.460.40
L Value (air leakage)00

Energy efficient


Noise reduction

Energy efficient

Reduced condensation

Increased security

Craig on location

Double glazing Vs. triple glazing an experiment

To visually see the difference between double glazing and triple glazing we conducted an experiment.

To demonstrate the thermal efficiency of windows, we used a thermographic camera that shows the heat loss from two sets of windows.

We chose identical houses next to each other. Woodbrook Cottage on the left has standard double glazing, Briar Cottage on the right has Everest Triple Glazing fitted.

We used an independent specialist who measured the windows early in the morning. The results above clearly show the difference between double and triple glazing. Heat loss is shown as red and yellow, with red being the most heat lost.

Woodbrook showed greater energy loss through window panes, frames, and doorways. Briar Cottage had only slight energy loss from around its window frames, with little to no thermographic differentials shown in the centre of the panes.

The survey was performed to provide a qualitative thermal performance comparison between two adjacent properties; Woodbrook House, with standard double glazing and Briar Cottage, with Everest A++ Triple Glazing.

Woodbrook Cottage Briar Cottage

Understanding the difference between thermal images:

The darker colours on thermal images represent colder surfaces, and the lighter colours represent hotter surfaces where heat is being lost.

Understanding thermal images

You can see the full report here.

Is triple glazing better than double glazing?

We would recommend triple glazing for:

  • North facing windows and cold rooms,  due to its exceptional heat energy efficiency.
  • Properties subjected to extreme weather such as exposed properties or next to the coast.

We recommend double glazing for:

  • Replacing existing windows in rooms that don’t face north or in exposed locations.
  • When noise reduction is the primary issue, we recommend specialist noise reducing double glazing.

If they are both made from the same material and to the same quality standard then the triple glazing should be just over 50% more energy efficient. However, there are lots of variables that can compromise the comparison between double and triple glazing:

  • Correctly spaced gaps between the panes.
  • Type of gas or coating used as the insulator.
  • Type and quality of the materials.
  • Level of tailored manufacturing to your home.

This means that it's possible for some lower quality triple glazing to be less energy efficient than good quality double glazing.

As the Future Homes Standards and Building Standards are introduced, the U-value and energy efficiency of a window are becoming more important. It is expected that triple glazing will become the standard for new build houses in the next few years.

To understand what is a better long-term investment for your needs, book an appointment with our specialist advisors who can recommend the right glass for you.

Explore window glazing

Double Glazing →

Our high-quality double glazed windows will keep your home warm, safe and quiet.

Triple Glazing →

Our triple glazed windows are our most energy-efficient, with an A++ energy rating.

For the ultimate comfort and energy efficiency in your home

The superior efficiency of triple glazing reduces carbon emissions, uses less energy to heat and creates living space comfort you can't compare.