Window U-Values: How Uw 0.67 Sets a New Standard
Our quadruple-glazed wooden windows achieve Uw 0.67 W/m2K on the ECO 92 profile. That is 40% better than premium triple glazing and meets passive house thermal requirements.
The U-value (Uw for whole window) measures how much heat passes through a window per square metre per degree of temperature difference. It is expressed in W/m2K. A lower number means less heat escapes through the window.
A single-pane window from the 1970s has a U-value around 5.0 W/m2K. Modern double glazing brought that down to approximately 2.8. Triple glazing, now standard in Scandinavia, reaches around 1.0. Our quadruple-glazed system achieves Uw 0.67. That is 88% less heat loss than single glazing.
In Nordic and Northern European climates where heating accounts for 50-70% of energy costs, the difference between Uw 1.0 and Uw 0.67 translates to thousands of euros in savings over a window lifetime of 60 years.
Building regulations across Europe set minimum U-value requirements. Here is how our windows compare:
| Standard / Region | Max Uw Required | Our Performance |
|---|---|---|
| UK Building Regs (Part L) | 1.4 W/m2K | 0.67 - exceeds by 52% |
| Germany (EnEV) | 1.3 W/m2K | 0.67 - exceeds by 48% |
| Sweden (BBR) | 1.2 W/m2K | 0.67 - exceeds by 44% |
| Norway (TEK17) | 0.8 W/m2K | 0.67 - exceeds by 16% |
| Passive House (PHI) Our target | 0.80 W/m2K | 0.67 - certified |
Our windows exceed the strictest building regulations in every European market we serve. See our full certification portfolio for independent test reports.
How does quadruple glazing compare to previous generations?
| Glazing Type | Typical Uw | Layers | Heat Loss Reduction |
|---|---|---|---|
| Single Glazing | 5.0 - 5.8 | 1 | Baseline |
| Double Glazing | 2.6 - 2.8 | 2 | ~48% |
| Triple Glazing | 0.8 - 1.0 | 3 | ~82% |
| Quadruple Glazing Windows Latvia | 0.67 | 4 | ~88% |
The jump from triple to quadruple is smaller in absolute numbers but significant in real-world performance. Each additional pane with Low-E coating and argon gas fill creates another thermal barrier. Learn more about our glazing options including specialist glass types.
Four glass layers is only part of the equation. The frame profile matters just as much.
Our ECO 92 profile (92mm depth) is engineered specifically to house four panes with optimal spacing between each layer. The engineered laminated timber frame is kiln-dried and bonded in layers to prevent warping, providing consistent insulation across the entire perimeter.
Each glass surface carries a microscopically thin Low-E metallic coating that reflects infrared radiation back into the room. With four coated surfaces, radiant heat transfer drops to near-negligible levels. Argon gas between the panes slows conductive and convective heat movement further.
ECO 92: Triple and Quadruple Glazing
Premium 115mm: Maximum Performance
Compare all three profile systems on our Window Profiles page: ECO 68, ECO 92, and Premium 115mm.
The Passive House Institute (PHI) sets a maximum whole-window U-value of 0.80 W/m2K for certified components. Our quadruple-glazed windows on both the ECO 92 and Premium 115mm profiles meet this requirement.
Architects and developers specifying passive house projects need windows that meet these requirements without compromising on aesthetics. Our tilt and turn and Scandinavian-type windows are both available with quadruple glazing.
For projects requiring fire safety alongside thermal performance, our fire-resistant windows (EI-30 certified) can be specified with triple glazing while meeting fire code requirements.
Certified to the highest EU energy class. Meets or exceeds building regulations in all EU member states.
Verified by accredited European laboratories. 41 test reports from TUV EESTI and Kiwa Inspecta.
Up to 40 dB sound reduction. EI-30, EI-45 and EI-60 fire ratings available (certified by TUV EESTI).
Upgrading from standard double glazing to our quadruple system reduces heat loss through windows by approximately 78%.
With a 60-year lifespan, cumulative savings substantially offset the upfront premium over triple glazing. Better thermal performance also removes cold drafts, lowers condensation risk and lets you specify a smaller heating system.
Latvian production means our quadruple-glazed windows sit 30-40% below Scandinavian prices for the same spec. We handle the full process through our full-cycle service.
Quick guide by region and local building regs. For an exact savings number, use the homeowner calculator below.
| Region | Climate | Recommended profile | Uw |
|---|---|---|---|
| Scandinavia (NO/SE/FI/IS) | Cold, long winter | Premium 115 + quadruple glazing | 0.6 |
| Germany / Austria / Switzerland | Cool temperate | ECO 92 + quadruple glazing | 0.67 |
| UK (Part L) | Mild, damp | ECO 92 + triple glazing | 0.78 |
| Baltics (LV / LT / EE) | Continental temperate | ECO 92 + triple or quadruple | 0.67-0.78 |
| Southern Europe (FR / IT / ES) | Warm | ECO 68 + triple glazing | 1.0-1.3 |
Need an exact figure - how much you save on heating with our windows at Uw down to 0.6? Enter window area, current Uw and climate zone, get euros per year.
Open calculatorUK Building Regulations (Part L) require a maximum Uw of 1.4 W/m2K for replacement windows. Our quadruple-glazed windows achieve Uw 0.67, exceeding UK requirements by 52%. For new builds, regulations are even stricter, making our windows an excellent specification choice.
For buildings in cold climates (Scandinavia, Northern Europe, UK), quadruple glazing delivers measurable energy savings. The upgrade from triple to quadruple reduces heat loss by an additional 30-40%. With a 60-year lifespan, the energy savings offset the price premium. See our quadruple glazed windows for full specifications.
Ug measures the thermal performance of the glass unit alone. Uw measures the whole window including frame, glass, and spacer bars. Uw is always higher (worse) than Ug because frames conduct more heat than glass. Always compare Uw values when choosing windows.
Yes. The Passive House Institute requires Uw below 0.80 W/m2K. Our quadruple-glazed windows on both ECO 92 and Premium 115mm profiles achieve Uw 0.67, well within the requirement. View our certifications for test reports.
For maximum thermal performance, the Premium 115mm profile with quadruple glazing delivers the lowest U-values. The ECO 92 with quadruple glazing is an excellent balance of performance and cost. The ECO 68 accommodates triple glazing for standard applications. Compare all options on our Window Profiles page.
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