Cavity Models

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Mauro Mini

Jan 14, 2024, 7:30:30 PMJan 14
I'm a new user of therm and I have some troubles with the model.
In fact, I don't know exactly how to model some parts of my component.

At first, the green part represent a simplified frame composed by alluminion alloy and internal cavities. How can I model an equivalent conductivity?
I saw that there is a material called "Frame cavity - CEN simplified". Is it correct to use it? What kind of material of the frame it considers for the calculation? (alluminion alloy or other?)

The second problem is about the area in yellow. It is a cavity filled with argon&air. Is it correct to model it as a solid with an equivalent conductivity?

Thank you all for the support,

Zugur Rakhmanov

Jan 15, 2024, 2:42:12 AMJan 15
to Mauro Mini, THERM
Could you provide the dxf/dwg section of your model?



пн, 15 янв. 2024 г., 03:30 Mauro Mini <>:
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Angus Collins

Jan 15, 2024, 5:58:42 PMJan 15
Hi Mauro,

It sounds like you're trying to over simplify your model to the point any data would not be particularly useful.

You should probably be able to access a DXF/DWG file for any aluminium framing system you have, which can be imported as an underlay and traced over, keeping in mind that you cannot draw a enclosed cavity as one piece (but you can draw it as two pieces, I.e. a RHS could be drawn as two channels)
If this is in a DWG file open it in autocad and export it as a earlier DXF file.

It also sounds like you're importing the glazing incorrectly, The entire DGU should be modeled in Window, then imported to therm.

Also keep in mind that the DGU spacer will have a large impact so an approximation of the spacer will also be required.

If you've been in the facade industry for a while you should already have access to some therm reports to give you a good idea on how to model your system.
If you haven't, you should probably wait until you've completed a few jobs and have a few reports others have completed so that you have at least some idea if the results you are getting are reasonable.

I've attached an example of the model complexity that would be expected if you're planning to use your models to justify ESD performance.

Finally read the therm manual which clearly states that the glass should be orientated up and down the page (Not across), you define the section as a sill/jamb/head etc, and change the gravity vector to account for real life orientation.



Mauro Mini

Jan 17, 2024, 7:40:52 AMJan 17
Thanks for your answer.
In fact, I don't have enough informations about the window.
So, I'm trying to simplify the model.
Now I modelled the frame with a solid with conductivity calculated from the trasmittance of the frame and did the same for the glass.
Unfortunatly when I try to find the linear trasmittance of the thermal bridge the value is always negative.
How is it possible?
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