Nature Optimo XL

Window NATURE OPTIMO XL is made entirely of wood and combines optimal combination of high energy efficiency, attractive appearance and affordable price. It is the most thermally efficient window of Nature Optimo family, which can be upgraded into passive window with the use of thermally modified spruce instead of normal spruce – NATURE OPTIMO XLT which was awarded as world most cost effective PHI certified passive timber window. Window has very nice outlook due to aligned frame and casement which is represented by letters L (Line) and X (Xclusive).


  • aligned casement and frame on both inner and outer window faces
  • thickness of both window casement and frame is 110 mm
  • hidden hinges
  • produced with the newest computer controlled technology implemented in 2014


  • contemporary design
  • suitable for low-energy and passive buildings
  • warm feeling
  • excellent water- and airtightness
  • long lifespan


  • Wind resistance (EN 12210): Class 5 (single casement) / C3 (double casement)
  • Watertightness (EN 12208): Class E1200 (single and double casement)
  • Air permeability (EN 12207): Class 4 (single and double casement)
Profile dimensions installation depth 110 mm
visible width 116 mm
Instalation options rectangular
arched, semicircular
Opening options fixed
combined (tilt and turn window)
folding walls
tilt-slide walls
lift-slide walls
opening outwards
two-sided handle
Thermal insulation of the window (Uw) Ug = 1,1  
Ug = 1,0  
Ug = 0,7 0,89 W/m²K
Ug = 0,6 0,81 W/m²K
Ug = 0,5 0,73 W/m²K