Double glazed uPVC windows vs triple
Double glazed uPVC windows are two panes with a sealed argon gap; triple adds a third pane. Triple is warmer and a little quieter; A-rated double is cheaper, lighter, and the right buy for most mainland Britain homes.
At a glance
| Item | A-rated double (standard) | Triple (option) |
|---|---|---|
| Glass unit | 28mm: 4mm low-E, 20mm argon cavity, 4mm clear | 36mm toughened, two cavities |
| Heat loss | Around 1.2-1.4 W/m²K, whole window | Lower, with a third pane |
| Noise | Good. Laminated is the better noise upgrade | A little quieter than double |
| Glass weight | Standard | Heavier, with a third pane |
| Condensation | Normal | Warmer inner pane, less internal condensation |
| Best for | Most homes | Cold-facing rooms, bedrooms, exposed sites |
What triple glazing costs
Triple glazing is priced by the square metre of glass, so the difference grows with the window. At today's prices (2 November 2026), choosing Triple glazed toughened (36mm) instead of the standard double glazing adds £50.24 on a 600 × 900mm Full Side Opener (£148.02 to £198.26) and £95.26 on a 1200 × 1200mm Classic Combination (£337.52 to £432.78), inc VAT. Only the glass changes; everything else is as the designer starts it.
As standard, each window is: Full Side Opener, an opening window, 600 × 900mm overall, white inside and out, double glazed (28mm), clear glass, 150mm cill, trickle vents: 2000 (300mm), white handles, standard key-locking espag lock; and Classic Combination, an opening window, 1200 × 1200mm overall, white inside and out, double glazed (28mm), clear glass, 150mm cill, trickle vents: 2000 (300mm), white handles, standard key-locking espag lock. Each price opens the designer at that window, so you can check it there and then try your own sizes. More options are priced in our window cost guide.
Prices include VAT at 20%. Delivery is extra: priced by straight-line distance from our factory (M28 2LY) to your postcode district, from £30, to mainland Britain addresses within 300 miles, not Northern Ireland, the Scottish Highlands or islands reached by ferry. Or collect free from the factory. Delivery and collection.
What comes as standard
Our standard unit is a 28mm double: 4mm low-emissivity glass, a 20mm argon-filled cavity with a warm-edge spacer, and 4mm clear glass. That specification achieves an A window energy rating in the Eurologik system (BFRC licence 3220). The triple option is a 36mm toughened unit with two cavities, for lower U-values and a touch more sound damping.
Warmth: the numbers that matter
The measure to compare is the U-value: heat lost per square metre, lower is better. A modern A-rated double glazed window sits around 1.2-1.4 W/m²K whole-window; triple glazing lowers the heat lost through the glass further. That's a real improvement, but on a typical replacement project the double-to-triple saving on your heating bill is modest, because an A-rated double unit has already eliminated most of the loss single glazing or a 1990s unit was costing you.
Where triple earns its keep: north-facing rooms, bedrooms where you want warmer internal glass on winter nights, new-build projects chasing a specific whole-dwelling target, and homes in exposed or upland spots.
Noise, weight and practicalities
- Noise: triple's extra pane and asymmetric cavities damp mid-frequency noise a little better; for serious traffic noise, our 28mm laminated acoustic-leaning unit is often the smarter upgrade than triple
- Weight: a third pane makes the glass unit heavier, fine in our frames, but worth knowing if you're handling large sashes on site
- Condensation: triple's warmer inner pane reduces internal condensation risk; external morning dew on very efficient glass is normal and harmless
- Cost: triple prices per square metre of glass, so the uplift grows with the window. The prices above show it on two sizes, and the designer shows it for yours in two clicks
Our recommendation
Buy A-rated double by default. Upgrade to triple where a room is cold-facing, a bedroom, or the project has a regulatory target to hit. Spend the difference on laminated glass where security or noise is the real concern. It's usually the better-directed pound.
Frequently asked questions
- Is triple glazing worth it in the UK?
- For most replacements, an A-rated double unit delivers nearly all the comfort gain at lower cost and weight. Triple is worth it for cold-facing rooms, bedrooms, exposed sites and projects with specific U-value targets.
- What is a warm-edge spacer?
- The spacer is the strip separating the panes at the unit's edge. Warm-edge spacers are low-conductivity composites rather than aluminium, cutting heat loss and cold-bridging at the glass perimeter. Ours are standard on every unit.
- Why argon gas?
- Argon is denser and less conductive than air, so the sealed cavity insulates better. It's standard in every unit we make.
- Can I mix double and triple in one order?
- Yes, glazing is chosen per window in the designer, so you can put triple in the north-facing bedroom and double everywhere else.
- Does triple glazing stop condensation?
- It reduces condensation on the room side because the internal pane stays warmer. Occasional external condensation on cold clear mornings is a sign the unit is keeping heat in, not a fault.
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