Dalite Rooflights

Thermal Performance

The Dalite range can be specified to exceed the thermal performance required by Part L of the Building Regulations. This will provide a more thermally efficient building, therefore lowering carbon emissions, and running costs. It will also create a positive contribution to BREEAM ratings, especially when combined with artificial lighting controls.

In order to meet Part L 2A of the Building Regulations, the rooflight unit will be usually required to have a U-Value of 2.2 W/m²K. Therefore Icopal recommend units which are at least triple skin glazed to achieve this value.

Triple skin polycarbonate units achieve a centre pane U-value¹ of 1.8 W/m²K and a Ud-value², which ranges from 1.25W/m²K for a 600x600mm dome to 1.51W/m²K for a 1200x2400mm dome.

Higher performance glazing options can further reduce the Ud-value to as low as 0.95W/m²K contributing to a more energy efficient building and BREEAM credits.  

Centre Pane  

Centre Pane
U-Value¹ (W/m²K)

Ud-Value² (W/m²K)



Double Skin Polycarbonate 2.7 1.54 2.09
Triple Skin Polycarbonate 1.8 1.25 1.51
Quad Skin Polycarbonate 1.4 1.12 1.25
Structured Polycarbonate Inner Glazing 1.2 1.06  1.13
Standard Glass Inner Glazing 1.21 1.06 1.13
Argon filled Glass Inner Glazing 0.9 0.96  

1 Centre Pane U-value is a measure of thermal efficiency of the glazing type.
2 Ud-Value is thermal efficiency of the developed rooflight unit.

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