Most people choose windows based on how they look or how many panes they have. But did you know that one of the most important parts is actually hidden between the glass? We’re talking about a warm edge spacer – a small but mighty element that can seriously boost your window’s performance. It helps improve insulation, reduce condensation and lower your energy bills.
In this article, we’ll explain what warm edge spacer bars are, how they work, and why every energy efficient window in the UK and Ireland should include one, just like the ones offered by Fenbro.
What is a warm edge spacer?
A warm edge spacer is a thin, non-metallic bar placed between panes of glass in double or triple glazing units. It runs around the edges of the glazing and maintains a precise, airtight gap filled with insulating gas, usually argon or krypton. This gap helps reduce heat transfer between the inside and outside of your home. Instead of metal, it’s made from low-conductivity materials such as rigid foam, fibreglass-reinforced plastic, or advanced thermoplastics, sometimes with a thin foil coating.
Do all windows have warm edge spacers?
Not necessarily. While warm edge spacer bars are now standard in most high-performance glazing, some budget windows still use outdated aluminium spacers.
Warm edge spacer bar vs aluminium – what’s the difference?
Aluminium spacer bars are cheaper to produce, which is why they’re often used in budget window systems. But it’s also a metal with high thermal conductivity, meaning it transfers heat very easily. In practice, this causes warmth to escape quickly through the edges of the glazing unit. The result is more energy loss, cold spots near the glass and a higher chance of condensation forming in colder months. In contrast, warm edge spacers are made from low-conductivity materials like thermoplastics or composite foams, which is the reason for their energy-saving benefits.
Benefits of warm edge spacer bars
Warm edge spacer bars make your windows work better and your home feel warmer, while also helping to lower heating costs. Here’s why more and more homeowners are paying attention to this feature:
Improved insulation and year-round comfort
As we highlighted above, these insulating elements reduce heat loss around the glass, improving energy efficiency and helping maintain a stable indoor temperature – warmer in winter, cooler in summer.
Lower energy bills
By keeping more warmth inside your home, your heating system doesn’t need to work as hard. Over time, this translates into noticeable savings on your energy costs.
Less condensation
The edge of the glass stays warmer, which helps prevent condensation build-up – especially during the colder months. This not only protects your windows but alsohelps reduce mould risk in your home.
Longer lifespan and better durability
This small detail helps reduce stress between the glass panes caused by temperature fluctuations. That means fewer seal failures and better long-term durability.
Warm edge spacer bar colours
It may be surprising, but this subtle element also affects how your windows look. While it’s placed between the panes, it’s still visible and can influence the overall appearance of the glazing. Modern warm edge spacer bar colours are designed to match different window styles and finishes. Here are the most common colours available:
- Black – a popular choice for minimalist or contemporary frames. A black warm edge spacer bar creates a shadow-line effect between the panes, making the glass appear deeper and more elegant.
- White – clean and discreet. While it’s a classic match for white frames, it also works well with various shades of grey
- Grey – a subtle, modern shade that blends well with light grey, silver or aluminium-look frames. Great for neutral, balanced designs.
- Bronze or brown – ideal for wooden-effect or rustic-style frames, offering a natural and traditional look.
Double glazing and warm edge spacers – a perfect match (but triple is even better!)
Most people are familiar with double glazing – two panes of glass separated by a spacer bar and a layer of insulating gas. If the divider between the panes is made of insulating material, the whole system becomes more efficient. Combining double glazing with this technology offers:
- Better thermal insulation around the glass edges
- Reduced risk of condensation
- Higher Window Energy Ratings compared to standard aluminium spacers
That said, if you’re aiming for top-level window performance, triple glazing with a warm edge spacer bar is the smarter long-term investment. The extra pane adds another insulating layer and when paired with this feature, the result is:
- Lower U-values
- Maximum comfort in all seasons
- Superior noise reduction
So while double glazing warm edge spacer bars remain a solid choice, most of our customers now opt for triple glazed warm edge units to future-proof their homes and reduce energy use even further.
A tiny feature, a big impact on your windows
Most people don’t think about what comes between the panes and that’s fair. It’s hidden, easy to overlook. However, it’s the part that helps keep the cold out, the warmth in, and the glass clear, even on the frostiest mornings.
Fenbro regularly offers deals on warm edge spacers. Right now, our Summer Promo includes a free warm edge spacer with every window – making it the perfect time to upgrade and save even more. Just one more reason your home will feel better, every day of the year. And that’s just one piece of the energy efficiency puzzle. To see how all the elements come together, check out our article that breaks down key window specifications and glazing types.
Frequently Asked Questions (FAQ)
What is a warm edge spacer bar?
A warm edge spacer bar is a non-metal strip that separates panes of glass in double or triple glazing. Made from low-conductivity materials, it improves insulation and reduces condensation, making windows more energy efficient.
How much does a warm edge spacer cost?
The cost of this feature varies depending on the window type and size, but it’s generally a small part of the overall glazing price.
What colours do warm edge spacer bars come in?
Most popular warm edge spacer bar colours include black, grey, white and brown.
What are the benefits of a warm edge spacer bar?
It improves insulation, reduces condensation and helps lower heating costs – all while extending the lifespan of your glazing.
