InsulatedGlassUnit(IGU)
The definitive transparent element of the building envelope. An engineered composite system of glass panes separated by sealed cavities filled with noble gases and enhanced with molecular-level low-emissivity coatings.
The low-emissivity (Low-E) coating on Face 3 prevents interior heat from escaping outward, while still allowing full transmission of visible solar light.
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.
Documented applications
TAV. DResidential Windows
Double or triple glazed windows integrated in timber, PVC or thermally broken aluminium frames.
Curtain Wall Facades
Structural glass bonded with silicone where the frame disappears leaving a fully glazed external surface.
Glazed Roofs (Skylights)
Mandatory laminated internal glass and toughened external glass for hail and snow load resistance.
Dynamic Glass (Electrochromic)
IGU units equipped with active films that switch from transparent to tinted by applying a low electrical current.
Thermal Transmittance Ug (W/m2K) — shorter bar = better insulation
TAV. EThe Ug value refers only to the glazed area. To calculate the complete window (Uw), add the frame performance (Uf) and the spacer thermal bridge (Psi_g). Lower Ug = less heat loss in winter.
Used in these systems
TAV. SReference regulations
2 norms- D.Lgs. 192/2005Implementation of Directive 2002/91/EC on the energy performance of buildingsIn force
- Dir. (UE) 2024/1275Energy Performance of Buildings - recast (EPBD)In force
Informational links to the regulatory framework. Always verify the current text on the official source.
Operational documents from this sheet
Specification clauses, site checklists and compliance dossiers generated from the graph — and kept in sync when a cited norm changes. Join the waiting list.
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