How to combine two shade layers into a BSDF

answered 2017-02-09 10:56:09 -0600

vidanovic
176 ●1 ●4

updated 2017-04-26 13:28:49 -0600

Determinant
1149 ●2 ●8

You can use WINDOW7.4 for that (no need for OPTICS). As you already mentioned, you would have to put one glass layer that you can create in WINDOW. Just put 1.0 for solar and visible transmittances (it is important to put for both of them). Then create IGU with two shades and perfectly transmitted glass in between. Latest step would be to create Report->Energy Plus BSDF IDF (the only way to get BSDF matrices printed out). Note that if you turn debugging on, WINDOW will create Debug folder with layer by layer BSDF, which would be good way to check if data that WINDOW is using are correct.

Updated: You do have to go into OPTICS, make a 100% transmittance glazing. Import that into WINDOW and use that as the layer for the above procedure.

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This doesn't seem to work. When I Calc just a single layer of this glazing in WINDOW to create the BSDF like I normally do, No Visible data is created in the BSDF, just empty <WavelengthDataBlock>. When I create an IG unit with this glazing I get the following error:

Error in angular dependence calculation. Allowable range for K is given as [1.000e-010, 5.000e-004] and K is calculated to be 2.341e-015.

Error: Specular (UV Band) calculation for ID = 85, Layer = 1, Wavelength = 0.320

Determinant ( 2017-02-09 15:31:55 -0600 )edit

Did you try to create BSDF of single layer with perfect transmittance by itself? You cannot do that by applying single perfect layer (physics in optical routines break). Can you put triple layer right away and see how that performs?

vidanovic ( 2017-02-09 16:15:42 -0600 )edit

I'll do you one better. I copied CLEAR_6.DAT (no changes). Created a triple glazing system with 1/2" air gaps. Added a shading layer: 1/2" Air + Venetian A0. Got same error. I think it has something to do with the lack of spectral data when copying CLEAR_6.DAT. But per above, already tried importing with full spectrum from OPTICS.

Error in angular dependence calculation.  Allowable range for K is given as [1.000e-010, 5.000e-004] and K is calculated to be 7.730e-022.

Error: Specular (Visible Band) calculation for ID = 86, Layer = 1, Wavelength = 0.500

Determinant ( 2017-02-09 16:58:14 -0600 )edit

Can you do that without using OPTICS. Do not copy any DAT file. Just got to glass library and create glass with perfect transmittances. Use that glass and not one copied from OPTICS. It is however interesting that you got the error by just copying data.

vidanovic ( 2017-02-09 17:37:12 -0600 )edit

I think I was misunderstood. In the example above CLEAR_6.DAT was copied in WINDOW, not OPTICS. I mentioned OPTICS because I also tried that.

Determinant ( 2017-02-09 17:56:25 -0600 )edit

I see now that visible optical data are not created. This seems to be a bug in WINDOW. Thanks for catching it. I will send you spectral data file that you can use to create glass layer in OPTICS which then you can import in WINDOW. When creating layer in WINDOW please put that layer to have very big conductivity and front and back emissivities equal to one. In this way you will be able to have thermal analysis of the system (please note that airflow will not be simulated correctly in this case) because "virtual" layer will block it.

vidanovic ( 2017-02-09 18:31:04 -0600 )edit

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