If you live in a chilly British home with rattling sash windows and eye watering heating bills, vacuum glazing probably sounds like magic. Ultra slim glass that keeps in as much heat as thick triple glazing and still fits in your existing frames feels almost too good to be true.
In this guide I will walk you through what vacuum insulated glass (VIG) actually is, how it compares with double and triple glazing, what it really costs, how long it lasts and when it is genuinely worth the investment. We will keep the language simple and practical, but the details are based on current data from manufacturers, building regulations and independent reviewers.
By the end you should feel confident deciding whether vacuum glazing belongs on your wish list or whether high quality double or triple glazing is a better fit for your home and budget.
Quick answer: when vacuum glazing is worth it
Let us start with a straight, non salesy answer.
Vacuum glazing is usually worth considering if:
You live in a cold, windy part of the UK and spend a lot on heating.
Your home has slim timber frames, period sash windows or a conservation area restriction that makes standard triple glazing impossible.
You want the warmth of triple glazing without thick chunky frames.
You plan to stay in the property long enough to benefit from lower energy bills and improved comfort.
It may not be worth the extra cost if:
You already have good quality modern double glazing in decent condition.
You live in a mild part of the UK with low heating demand.
You plan to move in a few years and will not see the long term payback.
Your budget is tight and you could first tackle cheaper wins like loft insulation and draught proofing.
The rest of this article explains why, with real numbers on performance, price and lifespan.
What is vacuum glazing or VIG glass?
Vacuum glazing, often called VIG glass or VIG windows, is a type of insulating glass unit where the space between two panes of glass is almost completely emptied of air. That space becomes a vacuum, which is a very poor conductor of heat. This is the same idea that keeps drinks hot or cold in a vacuum insulated glass bottle or a vacuum glass cup.How vacuum insulated glass is built
Two panes of glass, often 4 mm each, sometimes toughened for extra safety.
A very narrow gap between them, roughly 0.1 to 0.3 mm, that is evacuated to form a vacuum.
Tiny almost invisible support pillars (micro pillars) that stop the panes touching when air pressure pushes them together.
A special edge seal that can hold the vacuum for decades.
Low emissivity coatings to reflect heat back into the room.
Brands on the market use variations of this design. Many units are about 8.3 mm thick with centre pane U values around 0.4 W/m²K and life expectancy above 25 years.
Newer generations from companies working on products such as LuxWall VIG or VacuMax glass are pushing R values up to levels similar to insulated walls. That means the glass itself can insulate almost as well as parts of the building envelope.
How many types of glazing are there for UK homes?
When you start researching windows you meet a whole alphabet: IGUs, VIG, low E and more. Here is a quick breakdown of the main glazing types you will hear about as a UK homeowner:Single glazing – one pane of glass, very poor insulation, common in original Victorian sash windows.
Secondary glazing – an extra pane added on the inside, can help sound and heat without changing the outside appearance.
Standard double glazing – two panes of glass with an air or argon filled gap. Modern UK regulations expect whole window U values around 1.4 W/m²K or better.
Triple glazing – three panes with two gas filled gaps, thicker and heavier but more insulating. Typical centre pane U values are roughly 0.8 to 1.0 W/m²K.
Vacuum glazing or VIG – two panes with a vacuum gap, centre pane U values typically around 0.3 to 0.5 W/m²K in only 8 to 10 mm of glass.
Vacuum glazing vs double and triple glazing
Thermal performance and U values
The key number here is the vacuum insulated glass U value. Lower is better because it means less heat is leaking through the glass.R values of VIG glass
Many international manufacturers advertise the R value of VIG, which is the inverse of U value. R and U are just different ways of measuring the same thing. R is more common in North America and U in the UK and Europe. By definition R = 1 ÷ U.U of 0.4 W/m²K gives an R value of 2.5 m²K/W in metric terms.
High performance vacuum glass can reach R values comparable with very well insulated building components.
Noise, condensation and comfort
Comfort is not only about heat. Vacuum glazing can also improve day to day life in other ways:Noise reduction – many systems offer sound reductions around 36 to 40 dB, which makes busy streets feel more like a quiet library inside.
Less condensation – the inner pane stays much warmer, so you are less likely to wake up to streaming windows every winter morning.
More even room temperatures – you can sit closer to windows without feeling a cold draft or radiant chill.
Thickness and weight
Because the vacuum layer is so thin, VIG units are much slimmer than triple glazing.Many VIG products are around 8 to 10 mm thick for the glass unit.
Triple glazing units for similar performance typically need 36 to 44 mm of glass and spacers.
How much does VIG glass cost in the UK?
Here comes the uncomfortable part. The big downside of vacuum glazing at the moment is cost.Specialist UK fitters quote prices for vacuum glass of roughly £340 to £390 per square metre for larger units, before VAT, delivery and installation.
International ranges of about 100 to 400 US dollars per square metre line up with those UK figures once you factor in exchange rates and specification.
Industry comparisons suggest vacuum glazing can cost around 35 percent more than triple glazing and up to about 50 to 60 percent more than standard double glazing for similar window sizes.
On a full window replacement the glass is only part of the cost. Frames, manufacturing and fitting can dominate the bill, especially for complex bay windows or bespoke timber work. In those cases, upgrading the glass from double to vacuum glazing may add a smaller percentage to the final price than the raw glass figures suggest.
If you are just reglazing existing sash frames with VIG units, the cost difference becomes more obvious, because the glass is a larger share of the total.
Is there a simple payback period?
Unfortunately there is no single payback number that fits every home. It depends on:Your current glazing type and U values.
How exposed and windy your location is.
Energy prices in your area and how you heat the home.
Whether you can reglaze existing frames or need full new windows.
Lifespan and reliability of vacuum glazing
Standard insulated glass units usually last somewhere between 10 and 25 years before the seals fail and misting appears.High quality vacuum glazing is designed to last at least as long and often longer:
Many units come with a 15 year warranty and an expected lifespan above 25 years.
Laboratory ageing tests are designed to simulate decades of use without serious performance loss.
In practical terms, if you choose a reputable brand and installer, you can expect vacuum glazing to last at least as long as modern double glazing and probably longer, especially in the milder but damp British climate.
Pros and cons of vacuum glazing
Main advantages
Very high thermal performance for such a slim unit, with centre pane U values typically around 0.3 to 0.5 W/m²K.
Fits in slim frames including many heritage sash windows, avoiding the chunky look of triple glazing.
Excellent noise reduction which is ideal for busy streets and near main roads.
Less condensation thanks to much warmer inner panes.
Long life expectancy with 25 years and more commonly quoted by manufacturers.
Lower carbon footprint over time because better insulation cuts heating demand, especially in cold climates
Main disadvantages and risks
Higher upfront cost than even good triple glazing.
Technology is newer than standard double glazing, so fewer installers have long term experience and there are fewer brands in the UK.
Visible micro pillars and evacuation points may bother some people up close, although newer designs reduce or hide these features.
Not ideal for every frame because very old or damaged windows may still need full replacement, not just reglazing.
Embodied energy and manufacturing are more complex than standard double glazing, so you want to keep the windows in place for a long time to get the environmental benefit.
How to decide: a simple checklist for your home
List your problem rooms. Which rooms feel cold or noisy because of the windows? Bedrooms, living room, north facing rooms, stairwells?
Check your current glazing. Is it single, old double, or fairly modern double glazing? Are any units blown or misted?
Think about your frames. Do you have slim timber sash windows, chunky PVC frames, aluminium systems or a mixture?
Look up your energy use. How much are you spending on gas, oil or electricity for heating each year?
Decide how long you plan to stay. Five years, ten years, longer? The longer you stay, the more sense high performance glazing makes.
Get at least three quotes. Ask for prices for high quality double glazing, triple glazing and vacuum glazing where possible so you can compare like for like.
Ask specifically about VIG options. Use the term vacuum glazing or VIG and ask which brands the installer can supply.
How to choose a VIG glazing installer
1. Proven experience with vacuum glazing
Ask how many vacuum glazing projects they have completed in the past year.
Check whether they are approved or trained by specific VIG manufacturers.
Look for case studies or photos of homes similar to yours, especially if you have sash windows or a listed building.
2. Understanding of British regulations and heritage rules
They should know current UK Building Regulations for window U values and how their systems comply.
If you are in a conservation area or have a listed building, they should be familiar with your local planning authority’s approach to vacuum glazing.
3. Transparent quotes and specifications
Ask for the exact glass product name, quoted U values and any acoustic ratings.
Make sure the quote explains whether you are getting reglazing only or full new frames.
Check warranty terms for both glass and installation.
4. Aftercare and support
Good companies will explain how to spot early signs of failure and what is covered under warranty.
They should also talk honestly about lead times and any risks of delays for specialist products.
FAQs about vacuum glazing and VIG windows
What is VIG glass?
VIG glass means vacuum insulated glass. It is a sealed unit with two panes of glass and a vacuum gap between them, which gives very high insulation in a slim profile. You will also see it sold as vacuum glazing, vacuum insulated glazing or VIG windows.How many types of glazing are there?
For most UK homeowners, the main types are single glazing, secondary glazing, double glazing, triple glazing and vacuum glazing. Within those you can choose extras like laminated, acoustic, solar control or decorative glass depending on your needs.What is the R value of VIG?
It depends on the product, but high performance vacuum glass can reach R values that correspond to U values of about 0.3 to 0.5 W/m²K. That is similar to or better than many triple glazed units and far better than standard double glazing.How much does VIG glass cost?
In the UK, specialist suppliers quote vacuum insulated glass for sale at roughly £340 to £390 per square metre for common sizes, before VAT, delivery and fitting. The total cost for a window will also include frames and labour, so it is always worth getting a full installed quote, not just glass prices.Is vacuum glazing better than double glazing?
In pure thermal performance, yes. A good VIG unit loses much less heat than standard double glazing and can reduce noise and condensation more effectively. The trade off is a higher upfront cost and fewer installer options. For cold, exposed or heritage homes it can be a game changer. For an already well insulated semi with modern double glazing, the gains may be more modest.How long does vacuum glazing last?
Manufacturers expect their vacuum glazing to last over 25 years, with warranties typically around 15 years. That is at least as good as modern double glazing and in many cases better, especially where seals are protected from harsh climates.How much more expensive is vacuum glazing?
Estimates vary, but current figures suggest vacuum glazing units are roughly a third more expensive than triple glazing and up to about 50 to 60 percent more expensive than good double glazing. On full window projects the percentage uplift may be smaller because frames and labour dominate the cost.Can I just buy vacuum insulated glass online and fit it myself?
You will see listings for vacuum insulated glass for sale, but in most cases it is better to work with an experienced installer. VIG units are more delicate to handle than standard double glazing, and correct rebates, packers, sealants and tolerances are important for long life. For period sash windows this is especially true, so use an installer who regularly works with vacuum glazing.What about everyday vacuum glass cup products, are they the same thing?
No. Household items such as a vacuum glass cup or a vacuum insulated glass bottle use the same basic physics, but they are designed for drinks rather than windows. Building grade vacuum glazing must meet safety standards, resist weather, carry structural loads and stay clear for decades, which is why it needs specialist manufacturing and installation.
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