| Basic double glazing | Two clear panes with an air-filled cavity | Uninsulated or basic frame | About 2.4–3.0 W/m²K | Usually less efficient than low-emissivity (low-E) glass with an insulated cavity. | Budget replacements where high thermal performance is not the main priority. |
| Low-E double glazing | Low-E coating on a pane; air-filled cavity | Well-sealed, insulated frame | About 1.4–1.9 W/m²K | The coating reduces heat transfer through radiation; compare the specified coating and whole-window test data. | Many homes seeking a practical balance of cost and thermal performance. |
| Low-E with argon fill | Low-E glass with argon gas in a sealed cavity | Insulated uPVC, timber, or thermally improved metal frame | About 1.2–1.6 W/m²K | Argon can improve cavity insulation compared with air; correct cavity width and durable edge seals matter. | Homeowners prioritising lower heat loss without moving to triple glazing. |
| Acoustic-focused double glazing | Different pane thicknesses and, where specified, a wider cavity or acoustic laminated pane | Well-sealed frame with suitable opening design | Varies; request tested Uw and sound-reduction data | Sound performance depends on the full assembly, seals, installation, and noise frequency—not glass thickness alone. | Homes near roads, rail lines, or other persistent noise sources. |
| Solar-control double glazing | Solar-control coating; configuration selected for the building and orientation | Frame with good weather seals and appropriate ventilation provisions | Varies by glass and frame; compare certified Uw | Check the solar heat-gain value as well as Uw; reducing summer heat gain can also reduce useful winter sunlight. | Strongly sun-exposed rooms or homes that overheat in summer. |
| High-performance triple glazing | Three panes, typically with low-E coatings and gas-filled cavities | Deep, well-insulated frame designed to support the heavier unit | About 0.8–1.3 W/m²K | Can reduce heat loss further, but adds weight and cost; check frame compatibility and whether the home benefits from the upgrade. | Cold climates, exposed locations, or projects with demanding energy targets. |