May 9, 2023
The Future Buildings Standard which is looming over the horizon in 2025 is likely to mean a big increase in the use of triple glazing to meet the lower U-values that will be required. However, specifiers are starting to consider vacuum glazing as an alternative, due to its slim profile and comparable performance. With factors like triple glazing cost and the disadvantages of triple glazing coming under scrutiny, many are weighing up whether the higher vacuum glazing cost is worth it. But which is better? Well, it depends.
What does the Future Buildings Standard say about U values?
The Government has outlined its plans to deliver a “zero carbon ready” building strategy through its Future Buildings Standard. It aims to ensure that no new buildings from 2025 will require further retrofitting, with an uplift in energy efficiency standards, improved ventilation and requirements to mitigate overheating in residential buildings. A start was made on this last year with the changes to building regs and parts F, L and O which we have covered in previous blogs .
Following public consultation, a National Building Specification has been developed, setting out more stringent requirements for thermal performance.
Window U-values will need to be reduced from 1.2 W/m²K to 0.8 W/m²K, while doors (where more than 60% glazed) must achieve 1.0 W/m²K, down from the current 1.2 W/m²K.
This is likely to lead to triple glazing becoming the norm in most windows for new buildings or retro fits that want to achieve the highest performance.
What is triple glazing?
Very simply, triple glazing is an extra pane of glass added to the two used in double glazing but the benefits can be great. Up to now, many of our clients have opted for triple glazing in areas where they require high acoustic performance, with this comes much better thermal performance, saving money on fuel bills.
However, it’s important to weigh up the disadvantages of triple glazing, such as the added weight and higher triple glazing cost, particularly when comparing it to more modern alternatives like vacuum glazing. While vacuum glazing cost can also be a consideration, it offers better performance in a slimmer profile, making it ideal for heritage or listed properties.
What are the advantages of triple glazing?
- Excellent thermal performance that meets the new Future Homes Standard, will save you money on heating
- Great acoustic performance – ideal for blocking out noisy roads, aircraft noise etc
- Better security – thicker units are harder to break
- Can help to reduce condensation
What are the disadvantages of triple glazing?
- It costs more than double glazing but usually not as much as vacuum glazing.
- The windows are heavy which means they require chunkier frames and stronger fixings, all of which increase the price further.
- Aesthetically, some people dislike the look of the triple glazed windows because they aren’t as sleek as single or double glazed ones.
- Reduces the amount of heat from the sun limiting thermal gain. Harnessing solar energy is something homeowners have done for centuries and this is harder with triple glazed units.
What is vacuum glazing?
Vacuum glazing takes two pieces of glass with a tiny gap (0.1mm in the case of Fineo) and removes the air to create a vacuum.
This ultraslim profile offers quality thermal performance while maintaining the traditional appearance required for heritage or listed properties. Compared to triple glazing, vacuum glazing can achieve similar insulation without the added bulk, making it ideal where frame depth is limited.
While both options improve efficiency, triple glazing cost has its potential drawbacks, such as added weight and reduced light transmission, which can be a concern for period homes. Vacuum glazing cost may be higher upfront, but for many, the aesthetic and performance benefits outweigh the disadvantages of triple glazing in sensitive restoration projects.
They used to have unsightly plugs where the air was extracted, but the latest technology means this is no longer the case. Ultra-thin from as little as 7.7mm compared to 44mm for triple glazing, it’s great for listed historic properties or new builds looking for a sleek slimmer aesthetic.
What are the benefits of vacuum glazing?
- Ultra-thin profile – Vacuum glazing is 3-4 times thinner than triple glazing, making it ideal for listed and historic properties where traditional aesthetics are important.
- High thermal performance – Delivers insulation comparable to triple glazing. Fineo, for example, offers a U-value of 0.7 W/(m²K), outperforming the Future Homes Standard target.
- Greater durability – No gas between panes means there’s nothing to leak over time, resulting in a longer-lasting solution.
- Improved solar gain – Lets more heat from the sun into the room, helping to reduce energy bills naturally.
- Lightweight – Much lighter than triple glazing, making it easier to handle and install.
- More natural light – Allows up to 15% more daylight into your space compared to triple glazing.
- Environmentally friendly – Its lighter weight means lower transport emissions and less material usage overall. Longer lifespan also reduces the need for replacement.
- Excellent acoustic insulation – Helps keep external noise to a minimum.
- Aesthetic advantage – Slimmer, more elegant profiles work beautifully in both period homes and modern minimalist designs.
- Easier installation – Lightweight and thin design simplifies fitting, especially in existing frames.
What are the disadvantages of vacuum glazing?
- Typically it is the most expensive option compared with double and triple glazing, this is thought to be due to no UK manufacturers making it and the inherent cost of the materials, some use silver for example
- Low impact resistance — where micro pillars are used, it can put high stress on the glass.
How much does vacuum glazing cost?
Vacuum glazing can cost up to 56% as much as double glazing and around 35% times as much as triple glazing*.
*Prices may vary depending on size and spec.
So which should builders and architects choose from 2025?
Inevitably, it will end up coming down to price in most cases. We predict that most people will opt for triple glazing unless something drastic happens to the price of vacuum glazing, which may happen as the product becomes more popular and their production efficiencies improve. However, for anyone looking to balance the new regulations with heritage detailing, vacuum glass is the option that makes this possible.
We are getting more and more enquiries about vacuum glass from architects and specifiers who like it for its performance and great aesthetic qualities, but often value engineering means they have to fall back on triple glazing.
Tom Wright, MD, George Barnsdale
Contact George Barnsdale Today
If you’re considering upgrading your current windows to make sure that your glazing delivers the perfect balance of performance, aesthetics, and sustainability, our team is here to help. Whether you’re working on a heritage restoration or a contemporary build, we have a range of glazing options, including double and triple glazing, to ensure that you’re getting the best from your windows.
If you’d like to learn more about how we manufacture bespoke timber windows and speak to a member of our team, simply submit an enquiry via our contact page, and we’ll be in touch shortly to discuss your project.
