Glazing Mullion: How do I model?

Created by Vicki Marshall, Modified on Mon, 7 Nov, 2022 at 12:09 PM by Vicki Marshall

Region: All States

Assessor Question:

Can the team please advise what is the appropriate way to model the glazing mullion behind a concrete column? See below for extract of the window and plan detail of the section

TechLink Response:

The standard assumption for window system performance values is that the perimeter frame is fully exposed to the interior of the dwelling with respect to heat flows through the frame.
If the frame is fully embedded into the wall assembly fabric there is still a frame fraction but the window is effectively just the glass with respect to U-value and SHGC.
Where the mullions are fully embedded as indicated here the window width should be measured to include the aluminium mullion.
This will ensure correct inclusion of the frame fraction to arrive at accurate size of the glass area.
The window system U-value performance values can be extrapolated at an appropriate value between an equivalent window system values and the glass values.

frame fraction.
The other detail with the exposed glazing adaptor could be measured to the face of the fin if window system performance values can be determined for that window system which consists of glass installed in a thin glazing adaptor.