Glass comparison
Compare two to four supported constructions. Published ratings belong to the stated product and build; planning examples provide construction arithmetic without invented performance.
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4 of 4Side-by-side
Sourced / derived / unavailable| Property | Saint-Gobain XTREME 61/29 — 6 / 16Ar / 4 | Saint-Gobain COOL-LITE SKN 165 — 6 / 16 / 4 | Pilkington Optitherm S3 — 4 / 16Ar / 4 / 16Ar / 4 | Pilkington Optitherm S1A — 4 / 16Ar / 4 |
|---|---|---|---|---|
| Ordered construction | 6mm clear annealed (Saint-Gobain COOL-LITE XTREME 61/29 PLANICLEAR) (XTREME 61/29, face 2) / 16mm argon cavity (90% fill) / 4mm clear annealed (Saint-Gobain PLANICLEAR) | 6mm clear annealed (Saint-Gobain COOL-LITE SKN 165) (COOL-LITE SKN 165, face 2) / 16mm air cavity (100% fill) / 4mm clear annealed (Saint-Gobain PLANICLEAR) | 4mm clear annealed (Pilkington Optitherm S3) (Optitherm S3, face 2) / 16mm argon cavity (90% fill) / 4mm clear annealed (Pilkington Optifloat Clear) / 16mm argon cavity (90% fill) / 4mm clear annealed (Pilkington Optitherm S3) (Optitherm S3, face 5) | 4mm clear annealed (Pilkington Optifloat Clear) / 16mm argon cavity (90% fill) / 4mm clear annealed (Pilkington Optitherm S1A) (Optitherm S1A, face 3) |
| Nominal total thickness | 26mm including cavities | 26mm including cavities | 44mm including cavities | 24mm including cavities |
| Estimated mass per m² | 25.00 kg/m² (glass density estimate) | 25.00 kg/m² (glass density estimate) | 30.00 kg/m² (glass density estimate) | 20.00 kg/m² (glass density estimate) |
| Glazing Ug (W/m²K) | 1 W/m²K | Unavailable for this build | 0.6 W/m²K | 1 W/m²K |
| Light transmission (%) | 61% | 61% | 74% | 76% |
| Solar factor g (0–1) | 0.29 | 0.34 | 0.53 | 0.55 |
| Laboratory Rw (dB) | Unavailable for this build | Unavailable for this build | Unavailable for this build | Unavailable for this build |
| Spectrum adaptation C (dB) | Unavailable for this build | Unavailable for this build | Unavailable for this build | Unavailable for this build |
| Spectrum adaptation Ctr (dB) | Unavailable for this build | Unavailable for this build | Unavailable for this build | Unavailable for this build |
| UV metric (%) — source basis required | Unavailable for this build | Unavailable for this build | Unavailable for this build | Unavailable for this build |
| Impact / security classification | Not established by this reference — request evidence for the product and system. | Not established by this reference — request evidence for the product and system. | Not established by this reference — request evidence for the product and system. | Not established by this reference — request evidence for the product and system. |
| Source and limits | September 2026 manufacturer DGU reference; vertical glazing-only Ug, not whole-window performance. Confirm current UK product/processing evidence. Sources and scope | Manufacturer EN410 reference, 6/16/4, face 2. Gas not specified by optical source; air is a planning placeholder. Ug/UV unavailable. Sources and scope
| March 2020 exact vertical triple assembly; 90% argon in both cavities, faces 2 and 5; current DoP to confirm. Sources and scope | March 2020 manufacturer assembly; vertical, 90% argon, face 3; current DoP to confirm. Sources and scope |
Heat treatment alone does not improve acoustic performance. Low-iron glass reduces iron-related tint; it is not a promise of zero colour. Missing ratings cannot be inferred from another build. Mass excludes cavity gas and uses separately estimated interlayer mass.