Choosing between double or triple glazing is one of the most common questions homeowners ask when researching new windows and doors.
With energy prices rising and modern aluminium systems offering higher performance than ever before, it is sensible to understand the real differences before you commit. Double glazing in quality windows and doors will meet U-Values for New Build or Replacement Window and Door projects. Triple glazing will enhace your windows but might not always be the best option, because of extra cost, extra weight and other factors.
Our guide gives you a clear and honest explanation of how both options perform, where each is best used, and how the choice affects Aluco’s steel-inspired windows and doors.
What Double Glazing Actually Is
Double glazing is the standard for UK homes. Two panes of glass are separated by a warm-edge spacer bar and filled with insulating gas (typically argon). although Krypton gas is now widely available as are Vacuum Sealed Units for thinner sealed units in heritage windows.
A good double glazed unit today already offers excellent thermal insulation, low-emissivity coatings, and very good solar control options. It is also available as acoustic or laminated glass for enhanced security. Typical centre pane U-Values on a 28mm glass unit with this specification is around 1.0 to 1.1 Wm2K or less
Best for:
- Most replacement window projects
- Extensions that need a balanced temperature
- Planning Constraints where triple glazing may not be necessary
- Customers wanting lower cost without sacrificing performance
What Triple Glazing Offers
Triple glazing uses three panes of glass with two insulating cavities. This improves thermal performance and can noticeably reduce external noise in certain situations.
Triple glass units are often found in windows that can’t meet Buidling Regulations with double glazing, frequently as standard in hybrid windows (wood inside, aluminium outside) as well as windows specifically designed for acoustics, advanced insulation or stringent security requirements, using laminated and toughened glass.
What triple glazing improves:
- Even Lower U-values
- Better heat retention during winter
- Reduced cold spots around windows
- Improved comfort in highly exposed or coastal locations
Where triple glazing matters:
- New builds targeting high energy performance
- Homes near busy urban roads, although acoustic glass is best
- Properties in cold or exposed areas
- Large aluminium door sets where heat retention is important
Thermal Efficiency: Double vs Triple Glazing
U-values measure how well a window retains heat. The lower the number, the better the insulation.
Typical UK centre pane figures when deciding between double or triple glazing are:
Glazing Approx U-Value
Double glazing 1.2–1.4 W/m²K
Triple glazing 0.7–1.0 W/m²K
While triple glazing performs better on paper, modern double glazing—when paired with insulated aluminium frames—already surpasses UK Building Regulations with ease. For many homes, the difference in real-world heating bills is minimal unless the property is extremely airtight or built to Passivhaus-style standards.
It is also worth noting that taking brand X or some windows and adding triple glazing doesn’t automatically make the window more thermally efficient. This is because U-Values are calcultated with the frame and the glass in mind. This is why the overall product U-Value matters more than the centre pane U-Value of the glass only
Noise Reduction: Does Triple Glazing Make a Difference?
Yes, but one must not assume it is an instant improvement because there are many factors that make a difference to the acoustic performance of your new wiindows and doors. Triple glazing can reduce noise, but not always dramatically. The biggest improvement comes from glass thickness variation, not simply adding more panes.
For example, you can get improved acoustics by using laminated glass (used in acoustic glass already). Alternatively you could have a standard double glazed unit with thicker glass inside than outside. This can also help improve acoustics.
Triple glazing should improve the acoustics and create a quieter room, but it is always best to seek specialist advice from us or your Aluco Approved Installer. Here is why.
- The brand of glass and its make up matters
- You need to take into consideration the window frame as part of acoustic results
- The age and insulation of your home is a factor as well.
- Acoustic glass will make a difference, but your mileage may vary depending on where you live and how busy your road is.
In many Aluco installations, a good acoustic double glazed unit might even outperform standard triple glazing because it uses different thicknesses to interrupt sound waves.
You’ll notice the most benefit from triple glazing if:
• You live on a main road
• You live under a flight path
• You live beside a railway
Cost Differences: Is Triple Glazing Worth It?
Triple glazing typically costs more due to the additional glass, spacers and manufacturing time.
It is worth it when:
• You are building a new home with very high insulation targets
• You want the absolute best thermal performance
• Internal comfort in winter is a priority
It may not be worth it when:
• You are replacing windows in a standard home
• The building loses more heat through walls and floors than glazing
• You prefer slimmer sightlines (triple glazing can increase frame size with some products)
There are also two other considerations when comparing double or triple glazing for your windows and doors.
First is the added weight. Whilst our window and door hardware across our Elite Exterior Collection can comfortably take triple glazing, the windows and doors will invariably be heavier the larger they are. The other consideration is a small amount of visual; distortion as you are looking through three panes of glass instead of two.
Heat Gain in South-Facing Extensions
A surprisingly common concern is overheating in south or west-facing rooms.
Triple glazing can reduce unwanted solar gain because the extra pane reduces how much warmth enters the room. This is useful in:
• Large glass extensions
• Rooms with high afternoon sun
• Kitchens and open-plan spaces that already run warm
However, double glazing with the correct solar-control coating will also manage heat extremely effectively.
Glazing choice should match how your home behaves, not just the energy rating label. And there are also Part O of Building Regulations that is specifcally designed to prevent overheating in homes
A surprisingly common concern is overheating in south or west-facing rooms. Triple glazing can reduce unwanted solar gain because the extra pane reduces how much warmth enters the room. This is useful in:
• Large glass extensions also including a glass roof
• Rooms with high afternoon sun
• Kitchens and open-plan spaces that already run warm
However, double glazing with the correct solar-control coating will also manage heat extremely effectively.
Glazing choice should match how your home behaves, not just the energy rating label.
How Your Frame Quality Changes Everything (The Aluco Difference)
Whether you choose double or triple glazing, the performance of the frame matters just as much.
Aluco windows and doors use:
• Thermally broken, insulated aluminium
• High-performance warm edge spacer bars
• Low-emissivity safety glass
• Precision-engineered sealing systems
This means:
• An Aluco double glazed window often performs better than a cheaper aluminium triple glazed window
• The design integrity and airtightness of the system are more influential than the pane count
• Both double and triple glazing remain true to the slim, iconic steel-inspired aesthetic
We engineer the system around the glass, ensuring no compromise to the visual proportions Aluco is known for.
Double or Triple Glazing for Aluco Windows and Doors? Our Recommendation
Most Aluco customers choose double glazing.
It delivers excellent thermal efficiency, fits perfectly with our slim steel-inspired sightlines and provides outstanding year-round comfort.
Triple glazing is the right choice when:
• You want the highest possible U-value
• You live in a colder or exposed area
• You require increased noise reduction
• You’re building a new home with a high insulation standard
We support both options across the Aluco range.
Most Aluco customers choose double glazing. Our windows and doors come with 28mm units as standard having a soft-coat low-emissivity coating, warm edge spacer bars and argon gas fill. All glass is toughened in low level glazing and throughout every door set. Aluco Windows and doors promise excellent thermal efficiency, fits perfectly with our slim steel-inspired sightlines and provides outstanding year-round comfort.
Project Examples – What to Choose
Extensions:
Double glazing for balanced temperature. Triple glazing for sun-exposed rooms.
Replacements in traditional homes:
Double glazing recommended. Slimmer sightlines, lighter frames, superb performance.
New builds:
Triple glazing often ideal, but depends on SAP calculations and overall insulation strategy.
Urban locations:
Consider acoustic double glazing or triple glazing depending on noise levels.
Expert Help Choosing Your New Aluco Windows and Doors
Double glazing and triple glazing both deliver excellent performance when paired with high-quality aluminium frames. For most UK homes, premium double glazing in an Aluco system is more than sufficient. Triple glazing is beneficial in colder climates, acoustically challenging areas, or high-performance new builds.
If you are unsure, we recommend speaking to your Aluco installer, who can assess your home, your room layout and your energy priorities to help you make the right choice. Contact us for more information and details of your nearest showroom.
