Vacuum glazing vs single, double and triple glazing
Vacuum glazing is fast becoming the smart choice for homeowners who want efficiency without spoiling the look of their windows. It matches or beats triple glazing on performance while staying thin and light enough to fit inside existing frames. That combination makes it particularly attractive for heritage homes and listed buildings.
The quick take
U-values of 0.3–0.5 W/m²K, better than standard double and equal to high-end triple
Noise reduction in the mid to high 30s dB, more with laminated panes
G-values around 0.4–0.7 depending on coatings, with UV control options
Slim profile that looks like single glazing and keeps original sightlines
Light weight, so it can be fitted into old sashes without heavy alterations
| Feature | Single Glazing | Double Glazing | Triple Glazing | Vacuum Glazing |
|---|---|---|---|---|
| U-value (W/m²K) | 4.8–5.8 | 1.2–3.0 | 0.7–0.9 | 0.3–0.5 |
| Noise reduction (dB) | 20–25 | 30–40 | 40–50 | 35–45+ |
| G-value / UV | High unless treated | 0.4–0.7 | Lower with coatings | 0.4–0.7, adjustable |
| Thickness | 3–4 mm | 20–28 mm | 36–44 mm | 6–9 mm |
| Weight | Very low | Moderate | High | Light |
| Retrofit into frames | Yes | Sometimes | Rarely | Yes |
| Heritage friendly | Original only | Mixed | Rarely | Very strong |
| Cost | Low | Low to medium | High | Premium |
Why heritage officers like vacuum glazing
Vacuum glazing preserves the look of traditional windows. Its slim depth means original frames and sightlines remain intact. Instead of replacing sashes or widening rebates, installers can often carry out glass-only replacement.
Vacuum glazing preserves the look of traditional windows. Its slim depth means original frames and sightlines remain intact. Instead of replacing sashes or widening rebates, installers can often carry out glass-only replacement.
That minimal intervention fits conservation principles. Officers and planners appreciate that it improves efficiency and noise control without altering the character of the building. For listed properties it can often be the only acceptable way to meet energy performance targets.
Practical notes
Micro-spacers are visible on close inspection but not from normal viewing distance
Maximum pane sizes are improving but still more limited than standard double units
Cost is higher than triple glazing per square metre, but it avoids full frame replacement and pays back through energy savings and planning approval
Bottom line
Vacuum glazing delivers triple glazing performance in the body of a single pane. It is slim, light, heritage-friendly and effective. For listed buildings or period homes it is one of the most practical upgrades available today.