Vacuum double glazing is one of the most efficient ways to reduce heat loss in your home. With more effective windows, you retain more warmth indoors, which is especially important given rising energy prices and the recent surge in heating costs.
In this article, we explain what vacuum glazing is, why a flexible edge seal is essential, and why vacuum double glazing might be the best choice when replacing your old windows.
What is vacuum double glazing?
Vacuum glazing is an innovative window technology developed in Japan to reduce the weight of windows in earthquake-prone areas while maintaining exceptional thermal efficiency. Since then, it has evolved to offer outstanding energy performance, longevity, and acoustic insulation.
Like standard double glazing, it uses two panes of glass. Traditional units rely on a gas like Argon to fill the cavity, which slows the transfer of heat and sound. Vacuum glazing, however, contains no gas at all — just a vacuum. This makes it even more efficient and allows the cavity between the panes to be much slimmer.
Why is vacuum glazing more efficient than standard double glazing?
A vacuum provides better insulation because heat and sound cannot travel through it. Whether the cavity is 0.2mm wide or as vast as outer space, its insulating properties remain the same. Despite being ultra-thin, vacuum glazing outperforms gas-filled units, offering both superior energy savings and soundproofing.
This efficiency makes it ideal for both modern homes and traditional buildings — including those where single glazing is required for planning reasons. Our blog on 10 years of pioneering vacuum glazing in heritage windows dives deeper into how Gowercroft helped lead the way with this innovation.
Why does vacuum glazing look better?
Vacuum glazing is much slimmer than standard double glazing, with a cavity of less than 2mm. In contrast, conventional double glazing typically has a gap of 16–25mm, making units bulky and visually intrusive.
This subtle design is a huge advantage for heritage windows in listed buildings and conservation areas, where planning authorities require minimal visual change. Units like LandVac — the highest-performing vacuum glass currently available — are often approved where conventional double glazing would not be.
How is vacuum double glazing made?
Vacuum glazing is more complex to manufacture than standard sealed units. It involves several unique processes:
- Micro spacers: To prevent the panes from collapsing under pressure, tiny spacers (just 0.15mm thick) are placed in a grid pattern between the panes. These are barely visible once the window is installed.
- Vacuum seal: One pane has a small hole used to create the vacuum inside the cavity. The unit is placed in a vacuum oven, where air and moisture are extracted before the hole is sealed with a discreet plug, usually in one corner.
- Getter material: A getter is placed inside the unit to absorb any residual gas or moisture, helping maintain the vacuum over the window’s service life. Read more about this in our guide to vacuum glazing.
Why is flexible edge sealing important?
The vacuum between panes creates pressure that can strain the edges of the glass. Early vacuum glazing used rigid sealing techniques like:
- Solder glass: Fused powdered glass creates a hard seal but puts the glass under extreme stress during heating and cooling.
- Indium alloy: A softer metal alloy seal developed at Ulster University. Less stress on the glass but prone to micro-leaks and very expensive.
Flexible edge sealing, often made from ultrasonically bonded stainless steel foil, is now considered the best method. It creates a long-lasting vacuum without placing stress on the glass, greatly reducing the chance of cracking or unit failure.
What are the benefits of flexible edge sealing?
- No heat treatment required: Reduces stress on the glass during manufacturing.
- Better durability: More tolerant of thermal expansion and movement in service.
- Improved performance: Helps maintain a consistent vacuum over the unit’s lifetime.
Flexible sealing has become the gold standard for high-performance vacuum glass, including the units used in groundbreaking projects like this South Derbyshire Grade II listed farm.
Looking for beautiful, energy-efficient windows for a listed building, conservation property, or new build?
Explore Gowercroft’s award-winning range of vacuum glazing solutions or get in touch to discuss how flexible-edge vacuum glass could transform your project.
