Double Glazing vs Triple Glazing: Which Is Better?

✔ Triple-glazed windows have three panes of glass

✔ Triple glazing is around 50% more insulating than double glazing

✔ It’s also 10% to 20% more expensive than double glazing

Double glazing costs less than triple glazing, so you might be wondering if triple glazing is worth the extra expense.

We’ll explain all the differences in this article, by comparing the costs, benefits, lifespan, and more of double glazing and triple glazing. And we’ll tell you which is better depending on your situation.

Want to skip all the details and just find a double glazing installer? Then fill in our short form, and we’ll pass them on to qualified installers, who’ll be in touch.

What’s the difference between double glazing and triple glazing?

The difference between double glazing and triple glazing is that double-glazed windows have two panes of glass, whilst triple-glazed windows have three panes.

In both cases, the space between the panes of glass is quite thin – only about 16 millimetres or so – and filled with air or an inert gas like argon, krypton, or xenon.

For both double and triple glazing, the main purpose of having multiple panes instead of one is to reduce drafts and increase heat retention.

Should you get double glazing or triple glazing?

If you can afford the higher cost, you should get triple glazing. It has all the same benefits of double glazing, but it’s around 50% more insulating.

It’s for these reasons that triple glazing is a popular choice in countries that experience very cold winters, such as Sweden and Canada. It can help a home stay warm, and you’ll use even less energy doing so than you would with double glazing –  and less energy means lower energy bills.

That being said, not everyone can afford the extra cost of triple glazing. And if that’s the case, double glazing is definitely more than up to the task of insulating a home, since UK winters are relatively mild.

The table below sums up the similarities and differences between double glazing and triple glazing.

Double glazing vs triple glazing: cost

Triple glazing costs 10% to 20% more than double glazing, according to Everest, one of the UK’s largest double glazing companies.

On average, triple glazing costs between £660 and £4,320 per window, whilst double glazing costs between £600 and £3,600 per window.

Installation costs around £250 for a day’s work, so more windows means more time to install, which increases the overall costs of both double and triple glazing.

To give you an example, it costs around £13,120 to replace all the windows in an average three-bedroom house with triple-glazed ones, and £11,050 to replace them with double-glazed ones.

If you want to see whether you can get double glazing grants to help subsidise the costs, check out our guide.

The table below shows the average cost of buying and installing double or triple glazing, based on the number of windows in a property.

And remember, these numbers are just estimates. The cost of double and triple glazing will vary greatly depending not only on the number of windows a property has, but also the size and design of the windows, the material they are made of, and the time it takes to install them.

For example, the cheapest type of windows are made with uPVC frames. The price increases as you go from wood, to aluminium, to steel frames.

In terms of design, casement windows are the cheapest, with sash and tilt-and-turn windows costing more. Bay windows are the most expensive type of design.

Double glazing vs triple glazing: return on investment

Homeowners are likely to see a return on investment if they sell their property after installing double or triple glazing.

This is because installing either type of windows will increase the property’s value, by improving its Energy Performance Certificate (EPC). Properties with good EPC ratings can sell for up to 14% more, if they go from the lowest rating to the highest, according to a study by moneysupermarket.com.

In terms of savings from energy bills, most homeowners won’t see a return on their investment. It takes 55 to 60 years to break even on double or triple glazing through energy savings, but the windows will need to be replaced before then.

For context, replacing all your single-glazed windows with double glazing that has an A- energy rating (the fourth-highest) can save you around £195 a year on your energy bills according to the Energy Saving Trust. Triple glazing on the other hand, which usually has a rating of A++ (the highest rating), could save you around £235 a year.

But because triple glazing costs more than double glazing, the breakeven point without having to replace windows is relatively similar, despite extra energy bill savings.

Double glazing vs triple glazing: insulation

Triple glazing provides better insulation than double glazing. And it’s easy to understand why.

Triple glazing has three panes of glass and two air gaps, whilst double glazing only has two panes and one air gap. This means triple glazing provides more of a barrier against cold outside air.

This can be seen in the U-value of both double and triple glazing. The U-value of a window measures how good it is at stopping heat transmission – both from inside to outside, and outside to inside. The lower the U-value, the better the insulation.

On average, triple glazing has a U-value of 0.8, whereas double glazing has a U-value of 1.6. That’s an increase of 50% in heat retention for triple glazing when compared to double glazing.

Double glazing vs triple glazing: noise reduction

Triple glazing might reduce outside noise levels slightly more than double glazing, but the difference is minimal.

In general, both double glazing and triple glazing provide a 35 to 40 decibels (dB) reduction in noise, essentially reducing outside noise to the same levels as a quiet conversation. That’s around a 50% noise reduction when compared to single-paned windows.

More panes don’t necessarily equal less noise. What matters more is the spacing between the panes, their thickness, and the type of glass they’re made of.

Some glass, such as laminated glass – where a thin layer of polyvinyl butyral resin (PVB) is placed between two panes of glass – is specifically designed for soundproofing. Both double and triple glazing that’s made of this type of glass can reduce outside noise by over 50 dB.

Double glazing vs triple glazing: lifespan

Both double glazing and triple glazing have an average lifespan of at least 20 years. But this can vary between as little as 10 years, and as much as 35 years.

One factor that can affect how long double or triple glazing lasts is how exposed they are to the elements – frequent exposure to rain or sea air can accelerate degradation.

Poorly installed double or triple glazing will also last less than 20 years. And certain frame materials, such as uPVC, won’t last as long as other materials such as aluminium or wood.

Check out our guide to find out more about window lifespans.

Double glazing vs triple glazing: speed of installation

Both double glazing and triple glazing can take anywhere from four hours to three days to install, when replacing existing windows.

The speed of installation isn’t really affected by how many panes of glass are in a window frame. Instead, installation time depends on how many windows are being installed, how large they are, and their design.

To give you a better idea of what this means, one large window, or bay window, can take up to half a day to install. A regular-sized casement window, on the other hand, will usually only take 30 minutes to an hour to install.

Double glazing vs triple glazing: ease of maintenance

Double-glazed windows and triple-glazed windows are both very easy to maintain. The windows just need to be cleaned at least twice a year – more often if you live near the coast or in a dusty area.

Window cleaning can either be carried out by a professional, for around £50 to £150, or you can clean the windows yourself, with a soft cloth and either soapy water or window cleaning solution.

Of course, there’s always a risk of double and triple-glazed windows breaking or malfunctioning over time. Common issues include difficulties with opening or closing windows, locks breaking, condensation problems, or glass breaking or cracking.

If any of these occur, it’s best to contact your installer to have the windows checked and fixed. Repairs cost anywhere from £80 to £300, depending on the severity of the damage.

Next steps

Triple glazing provides a property with better insulation than double glazing. That means you’ll use less energy to heat your home, and receive lower energy bills.

So if you can afford triple glazing, there’s no real reason not to get it. But, if you can’t afford the higher costs, don’t worry. Double glazing provides enough insulation for a home to cope with the UK’s winters.

If you think double glazing is a better option for you, and you want a quote, we can help. Just put a few details into our short form, and our network of professional window installers will be in touch.

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