Vacuum glazing – sometimes referred to as vacuum double glazing – uses a sealed vacuum between two panes of glass instead of the argon or other inert gases found in standard double glazing. With no air or gas molecules to transfer heat, a vacuum is an exceptionally effective insulator, much like the principle behind a vacuum flask.
The result is a window that excels at retaining warmth in winter and keeping interiors cooler during hot spells. Another benefit is its slim profile: because the vacuum does the insulating work, vacuum glazing can be noticeably thinner than conventional double glazing while still offering high thermal performance.
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But with a vacuum, you don’t need that much of a gap. So where space is a premium, perhaps with an older building, this can be a plus.
How long does vacuum glazing last?
Like double glazing, vacuum glazing typically lasts between 10 and 25 years, depending on the quality of the unit and how well it’s maintained.
What is the difference between vacuum glazing and double glazing?
The key difference lies in what sits between the two panes of glass. Traditional double glazing uses a sealed gap filled with an inert gas such as argon to slow the transfer of heat. Vacuum glazing, by contrast, removes the gas entirely, creating a vacuum between the panes. Because a vacuum contains no particles to conduct heat, it offers significantly better thermal insulation in a much slimmer profile.
There are structural differences, too. Vacuum-glazed units typically use tiny support pillars between the panes to prevent the glass from collapsing under atmospheric pressure. These are engineered to be barely visible once installed. Double-glazed units, meanwhile, rely on a wider cavity to achieve their insulating performance, making them thicker overall.
In practice, this means vacuum glazing can deliver similar – or better – thermal efficiency than standard double glazing while allowing for thinner, lighter window units. This can be particularly useful in homes with narrow frames, period properties that need discreet upgrades, or where maintaining the appearance of original windows is a priority.
Is vacuum glazing more expensive?
You may well have guessed the major downside – cost. It’s harder to create a vacuum, especially in a bespoke window with a unique size, than it is to fill it with gas.
But in some circumstances, perhaps where the choice might be single glazing or vacuumed double glazing, it may be the only sensible choice if you have the money, because of how much heat single glazing can lose.
Vacuum glazing is a popular choice for sash windows because of its relative expense, no matter which glass you choose.
How much does vacuum glazing cost?
A new bay window can cost £1,000 to £3,000 or even more. If you are paying that much, the cost of the glass itself can be dwarfed by the cost of making the frames and fitting them.
Vacuum glazing costs between £340 and £390 per square metre, excluding VAT and delivery, according to specialist fitter Six Over Six. Their units are made in the EU and can attract an extra fee if energy prices are particularly high.
Meanwhile, regular double glazing with a low-e coating to reduce heat loss costs from £30 to £70 per square metre, according to Eco Happy, a fitter.
So you can see there’s a big difference. But this figure isn’t much use without knowing how much the frames and labour costs are, and those depend heavily on your choices from the cheapest uPVC options to handmade timber frames.
A uPVC double-glazed window including VAT, fitting, frames and everything else can cost under £600, by comparison. So going for a vacuum unit could easily add 50 per cent to the cost, and that would be for the cheapest frames.
Is vacuum glazing better than double glazing?
The two types of glazing last from 10-25 years, depending on how they are looked after and the warranty the manufacturer applies.
The expense today of vacuum double glazing means that it is unlikely to be a popular choice outside of specialist applications because of its cost.
It is technically superior, but it is also a lot more expensive, and it is likely that most buyers will get similar performance from triple glazing, which is only about 15 per cent more expensive than double glazing.
In a door, it is likely you will have more room to play with to install cheaper glass.
Is vacuum glazing worth it?
So, is vacuum glazing worth it? That depends on several factors. Whether vacuum glazing is a good investment depends on a number of factors. For it to make sense, you will need to recoup the extra cost – the cost beyond regular double or triple glazing – in reduced heating bills.
This will depend on the size of the windows, the size of your home and other energy efficiency measures you have already put in place.
It won’t be much use having super-efficient windows if you have a draughty home with no loft insulation, for instance. The heat will simply escape elsewhere.
