Sub-Zero window

"Sub-zero" is a CE approved inward opening aluminium clad triple glazed timber window system with whole window U value of 0.8 W/m2K (or 0.7 with Purenit frame insulation), making it suitable for use in passive dwellings. The sub-zero system includes inward opening bi-fold and sliding doors. 88mm timber frame depth + 18mm aluminium cladding = 106 mm total frame depth.

Performance ratings

  • CE approved 
  • Suitable for passive buildings 
  • Triple glazed 
  • Multiple gaskets 
  • Laminated knot free timber 
  • Window U value as low as 0.7


Air permeability 600Pa Class 4

Watertightness class E1950


Triple gaskets protect against air and water leakage.


Roto NT locking fittings with micro-ventilation and anti-burglary catch.


48mm triple glazing with Argon and warm edge technology gives centre pane U value of 0.5.


Sigma microporous water based coating system.

Opaque paints according to RAL and NCS colour charts.

4 layer coating system, impregnation, primer, undercoat, topcoat.

10 year guarantee against rot and fungal infection.


Summary sheet Download