An insulated glass unit is no longer a simple barrier against the wind. It is a complex thermodynamic machine, capable of selecting the wavelengths of the electromagnetic spectrum to let light in, repel summer heat and retain winter heat.
A single pane disperses enormous amounts of energy (Ug = 5.8 W/m2K). The sealed cavity of an insulated unit creates a first insulating barrier, but the air inside undergoes convective motion. Replacing it with heavier noble gases such as Argon or Krypton halves heat transmission. The real leap is the Low-Emissivity (Low-E) coating: a magnetron-sputtered deposit of silver oxides a few nanometres thick. This invisible film works as a selective mirror: it lets visible light through but bounces back infrared waves, preventing the heat from radiators from escaping outwards.
Contemporary regulations prohibit the use of fragile glass at risk of cutting. At least one pane must be laminated: two sheets of glass joined by a PVB film. The use of acoustic PVB, combined with asymmetric thicknesses, exploits the mass-spring-mass principle to prevent glass resonance, blocking external traffic noise.
Standards
European and international references applicable.
Physical properties
Usage environment
External architectural envelopes, curtain walls and windows. Always verify Ug + Uf + Psi_g for the complete window Uw calculation.