TripleGlazingLow-E
The ultimate evolution of the IGU for nearly zero energy buildings (nZEB). Three panes, two Argon-filled cavities and double Low-E magnetron coating to halve heat losses compared to standard double glazing.
The third pane physically halves gas convection. Two low-emissivity coatings (Faces 3 and 5) lower the thermal transmittance Ug to values approaching 0.5 W/m2K.
In harsh climates or for Passivhaus architecture, double glazing is no longer sufficient. Inserting a third central pane revolutionises the thermodynamics of the window, creating a transparent element that insulates almost as well as a brick wall.
In a double-glazed unit, the optimal space for Argon gas is 16 mm; beyond this measure, the gas triggers vertical convective motion that worsens insulation. The third pane divides a very thick cavity into two separate, sealed chambers, cancelling out convection. Above all, it provides an extra surface to host the magnetron coatings: using two Low-E coatings (Faces 3 and 5), a double trap for thermal infrared is obtained, halving transmittance compared to the standard.
Three layers of normal glass would create a dense visual filter with a greenish light. The central pane in extra-clear (low-iron) glass, free of iron oxides, is therefore mandatory. Structurally, each pane adds 2.5 kg/m2 per millimetre: a large French door can weigh over 100 kg, requiring heavy-duty hardware.
Standards
European and international references applicable.
Physical properties
Usage environment
Cold climates, Passivhaus and nZEB standards. Caution: the central third pane can overheat in hot climates. Use toughened glass (ESG) for the central pane on south-facing facades.
Documented applications
TAV. DPassivhaus (nZEB) Buildings
Mandatory standard for zero-energy houses, exploiting winter solar gain while eliminating thermal losses.
Cold and Mountain Climates
Extreme use at altitude where Face 6 temperature must remain mild even at -10 degrees C outside.
Large Fixed Panoramic Glazing
Non-opening glazed walls for full-glass living spaces without the cold wall sensation.
Maximum Acoustic Comfort
Asymmetric systems where the third pane mass eliminates low-frequency noise (heavy traffic).
Thermal Transmittance Ug (W/m2K) — shorter bar = better insulation
TAV. EEvery millimetre of glass thickness weighs exactly 2.5 kg/m2. Designing large opening triple-glazed panels, the sash weight can easily exceed 250 kg, requiring steel tracks and motorised mechanical carriages.
Reference regulations
3 norms- D.Lgs. 192/2005Implementation of Directive 2002/91/EC on the energy performance of buildingsIn force
- D.M. 26/06/2015Minimum energy-performance requirements for buildings (the 'minimum requirements decree')In 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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