Glazing Options

All Rationel windows are fitted with highly energy efficient glazing, with a warm edge spacer fitted as standard to help reduce cold bridging. Environmentally friendly argon gas is filled between the glass panes to reduce heat loss and a think transparent metal film is applied to the internal pane to help prevent heat from escaping out of your room.

Available in a wide range of options including obscured, acoustic coloured, enhanced security and much more, find out more below.

OBSCURE - Frosted or patterned glass

Rationel OBSCURE is designed to restrict the view into the private areas of your home, perfect for bathrooms. The obscure glazing is placed on the inside of all glazing panels ensuring they are easy to clean.


Different levels of sun protection

The level of sun protection provided by a window is determined by the amount of sunlight and the amount of the sun’s heat that are allowed to pass through the glazing. Sunlight is known as the Light Transmittance (LT-value) and the heat is known as the Solar Heat Gain (g-value). Other factors that may be considered are Energy Absorption (EA) and Energy Reflection (ER), these are the percentages of solar radiation absorbed by the glazing and the solar radiation reflected by the glazing.

  • Sun SKN176:Approximately 64% transmittance*, 35% solar gain**
  • Sun SKN165:Approximately 55% transmittance*, 31% solar gain**
  • Sun SKN154:Approximately 47% transmittance*, 26% solar gain**

*= LT-value    **= g-value

In comparison, a standard non-solar glazing would offer in the region of 74% light transmittance and 53% solar gain.
NOTE: All examples for triple glazed window elements.


Triple glazed

– Best performance: 0.79 W/m2 K U-value
– 42 dB Rw sound reduction

Double glazed

– Best performance: 1.29 W/m2 K U-value
– 40 dB Rw sound reduction