Triple Glazed Windows: The Ultimate Guide

Triple glazed windows are different to double glazed windows in that they're made up of 3 panes of glass instead of 2.

Triple glazing will reduce your energy bills whilst making your home warmer, safer and quieter.

The average cost of installing triple glazed windows in a 2 bedroom home is around £2,000. For a 4 bedroom house with 15 windows, you can expect to pay around £6,000 to £7,000.

What Is Triple Glazing?

what is triple glazing

Triple glazing is made up of 3 panes of glass, instead of just 1 or 2. Between each pane of glass is a small gap which is filled with air or an insulating gas, like argon. Because of this extra pane of glass, triple glazing is better at reducing heat loss and keeping your home warmer. It also helps to insulate your home from outside noises, and improves your property's security.

Triple glazing is most popular in cold climate countries such as Switzerland and Norway, but it's becoming more popular in the UK as homeowners begin to realise its additional benefits to single or double glazing.

In This Guide to Triple Glazed Windows:

Head straight to a specific section by clicking the links below.

Triple Glazed Windows Cost

Triple glazed windows typically cost more than double glazed windows. For example, a £350 double glazed window will cost around £485 for the same window with triple glazing. Triple glazed windows prices will vary depending on the style, size and frame of the windows you choose.

The table below provides you with an estimate of how much it costs to buy and install triple glazed windows, depending on the size of your home and how many windows it has:

Property Type
Number of Bedrooms
Number of Windows
Typical Cost

The more triple glazed windows you install, the cheaper each window will be. This means that the more windows you have installed, the more money you can save. It's therefore more cost effective to change all your windows to triple glazing, rather than just a few.

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How Much Can You Save?

Replacing single glazed windows (or even old double glazed windows) with new triple glazed windows can save you a lot of money on your energy bills. A well insulated, detached house could save up to £175 per year on energy by replacing single glazing with triple glazing.

The table below shows you how much you can save every year on your energy bills by replacing old single glazing with triple glazing:

Energy Rating
Detached House
Semi-detached House
Mid-terrace House
£135 - £175
£85 - £125
£75 - £100
£130 - £170
£85 - £120
£70 - £95
£120 - £160
£80 - £110
£65 - £90

How Much Would Triple Glazing
Cost For Your Home?

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What Are the Pros and Cons of Triple Glazing?

pros and cons of triple glazing

Triple Glazing Benefits

Reduces heat loss, making your home feel warmer

More efficient, lowering your energy bills

Harder to break, improving your home's security

Better at blocking out noise from outside

Triple Glazing Drawbacks

More expensive than double glazing

Longer return on investment than double glazing

Allows in less light

Heavier and can cause structural damage to your home's walls

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Triple Glazing vs Double Glazing

Unlike triple glazing, double glazing traps air (or an insulating gas) between just two panes of glass instead of three. Double glazing provides all the same benefits as triple glazing like enhanced heat retention and sound insulation, but are these benefits improved even further with three panes of glass instead of two?

Thermal Performance

The energy efficiency of a window is measured using the U-value, which measures how well a window prevents heat escaping from your home. The lower the U-value, the better a window is at retaining heat.

New double glazing has a U-value of around 1.6, whereas new triple glazing has a slightly better U-value of about 0.8. But what does this mean? Put simply, triple glazing will make your home that little bit more comfortable than double glazing by keeping the air temperature in your home just a few degrees warmer. This means you'll be able to save a little more money on your energy bills with triple glazing than with new double glazing.

Triple glazing's superior thermal performance has meant it's been awarded an energy rating of A++ - the highest rating possible. The maximum energy rating that double glazing has received is A+.

Good to know: the most thermally efficient triple glazed windows will have a gap between the panes of glass of around 16 to 20mm, filled with argon gas or air.

Sound Insulation

Triple glazed windows are a bit better than new double glazed windows at insulating your home from external sounds, because of their extra pane of glass. So if you live in a noisy area, such as on a busy road or below an airport flight path, the amount of noise that can enter your home from outside will be slightly more reduced.

Home Security

The extra pane of glass that comes with triple glazing means that your windows are stonger and harder to break than double glazed windows. Combined with security features such as multipoint locking systems and toughened glass, triple glazing can give you more peace of mind over the safety of your home. In fact, some window companies are so confident about the security of their triple glazed windows, that they offer customers a money-back guarantee should their home be broken into via their windows.

Light Penetration

Because triple glazed windows are made up of more glass, they actually let in less light than double glazed windows. This means your home's interior will feel a bit dimmer, so we wouldn't recommend installing triple glazing on north-facing windows that get little sunlight.

is triple glazing worth it
*Responses based on a survey we ran in May 2018 of 395 UK homeowners who've had triple glazed windows installed in the last 2 years.

You might also be interested in:

Which double glazed windows are best?

How Much Would Triple Glazing
Cost For Your Home?

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Triple Glazing Cost vs Double Glazing Cost

As you might expect, triple glazed windows are more expensive than double glazed windows. To give you an idea of the difference in price between triple glazing and double glazing, we've put together the table below which shows you the cost of different sized uPVC windows:

Size (mm)
Double Glazing Cost
Triple Glazing Cost
White uPVC
1660 x 992
White uPVC
1880 x 1061
White uPVC
2050 x 1133
Woodgrain uPVC
1660 x 992
Woodgrain uPVC
1880 x 1061
Woodgrain uPVC
2050 x 1133

Although triple glazed windows can save you more money on your energy bills than double glazed windows, the payback period for triple glazing is likely to be as long as for double glazing because of its higher upfront cost.

Click here for more information on double glazing costs

Is Triple Glazing Worth It?

If you already have new double glazing with an energy rating of A or A+, it's not worth installing triple glazing as the additional benefits you'll experience from an extra pane of glass will be very small. In these circumstances, if you are looking to improve the thermal or acoustic insulation of your windows, it's much more cost-effective to a) add secondary glazing onto your existing double glazing, or b) install thick curtains in front of your windows.

Triple glazing does make financial sense, however, if you have old, inefficient double glazing (or even single glazing) and want to maximise your home's energy efficiency. By installing triple glazing, you'll be able to save a lot more on your energy bills.

The image below shows a thermographic survey comparing old double glazing (left) to triple glazing (right). Red spots show where large amounts of heat are leaving the property, and you can see how much worse old double glazing is at retaining heat than triple glazing.

Triple Glazing Comparison Against Double Glazing

If your home is quite old and poorly insulated elsewhere (e.g. in the walls and loft), however, triple glazing won't be worth the cost. Why? If heat can easily escape from other parts of your property, you won't notice the benefits triple glazing has to offer. This is why it's best to install triple glazed windows in properties that are already energy efficient as a whole.

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Triple Glazing Companies

Many homeowners use a well-known nationwide company to install their triple glazed windows, such as Anglian or Everest. The table below provides you with information about the triple glazing offered by the big national installers, including their energy efficiency rating:

Product Name
Energy Rating
Product Guarantee
Triple PVCU
5 to 10 years
Triple Glazed Casement

Many smaller, local window companies also offer triple glazing - you don't need to use a national installer. Whatever company you do use, you must make sure that it's registered with FENSA or the Glass and Glazing Federation (GGF). These Competent Person Schemes (CPS) work with window companies to ensure that they comply with the UK Government's building regulations. Approval from a CPS makes sure you avoid any unauthroized or 'cowboy' installers.

We recently carried out a survey of 395 UK homeowners who've had triple glazed windows installed in their property in the last 2 years. Here's what they had to say about the different triple glazing companies:

% of Customers Who Felt Pressured to Sign a Contract
% of Customers Who Rated Their Installation as Good to Excellent
Local Installer

To get a personalised quote for triple glazing from a quality installer in your local area, simply click on the orange button below to fill in a short form with some basic details about you and your home:

How Much Would Triple Glazing
Cost For Your Home?

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