Glass and Frame in a Curtain Wall

grasshopper honeybee[+]
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1

Hi,
I would like to model a facade with spandrels and vision glass but I don’t know how to assign the constructions for a correct thermal calculation.
I modeled the frame as a surface separate from the glass part.

Screenshot (2015)
Screenshot (2015)1366×768 135 KB

I saw that there is the EPWindowMaterial component that requires an overall U-value of the frame and glass, but I would like to be able to separate the frame and glass to attribute a U-value to the frame and a U-value to the glass.
I would like to use the same U value for the spandrel frame. Spandrel is composed of glass and insulation.
The transmittance of the node is important to my work.
Thanks for your help

2

If you use a tool like LBNL window, you’ll be able to calculate U-Value of glass with a frame. And that is how the thermal transmittance of a glazing assembly is represented in an energy model.

Is there’s a specific reason to do that?

3

Hi Devang,
thanks for your reply. The reason is that the facade is made up of window elements (vision) and opaque elements (spandrel) that have an aluminum frame in common.
If I assigned a U value of glass with a frame to the glazing assembly I wouldn’t know how to characterize the frame of the opaque element
Thanks for your help

4

The question is why do you wish to characterize frame separately?

5

Hi Devang, thanks for your replay.
I wish to characterize frame separately because the European standard UNI EN ISO 10077 allows to calculate the transmittance of the window in this way:
Uw=(Ag Ug+Af Uf+Ig *ψg)/(Ag+Af )
However, I realized that Honeybee uses an American standard for thermal calculation. So I followed your advice and tried to use the LBLN window tool but I don’t know how to add an insulating layer made of rock wool in my glazing system. Some advice?
Thanks in advance

6

Hi,
in the LBNL window it is not possible to insert an opaque material such as an insulating layer in the description of the glazing system. If you have already modeled the separate surfaces for glass, frames and spandrel, simply assign a windowsmaterial to the glass and build a construction as a set of materials on multiple layers: one construction for the frame and one for the spandrel, where a outside layer of the spandrel will be an opaque material with the characteristics of thickness, conductivity, density, etc. of your glass.Use well the three characteristics of absorbace that you find in the material to simulate the reflections that your spandrel will have.