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Hello everyone,

i am working on complex fenestration systems (CFS) with strong angular dependent transmittance. I wrote a raytracing tool (which i validated) to compute transmittance for various angles.

I later added interfacing to Radiance for daylight computations.

i also added a Perez sky model (diffuse and Direct) to obtain hourly solar gains based on the transmittance. I included a small nodal RC model for a rough estimate of thermal loads in a room.

I would like to validate it against an other tool. it seems like e+ could do the trick. So far i am considering using Construction:ComplexFenestrationState and the 4 matrices (T and R, front and back) and 2 vectors (abs front and back). I am slightly familiar with the XML format used in WINDOW 7 and in Radiance to describe CFSs based on these same matrices. I understand the Basis "LBNLWindow" refers to this representation.

A year ago, when i added the xml representation to my tool for the Radiance part, i did not find a description of this representation and implemented it by studying examples, by trial and error and using the BSDFViewer to "validate" the results. I did it only for the Front transmittance. I need to extend it to Back transmittance and to reflectances. I would like to avoid this uncertain and cumbersome approach. Is there a detailed description available?

I found the relative section in the engineers documentation of Energy plus (pp 170 and on). This helps a little but is still don't know where the patches stop and end...

So the main question here is: Where do patches start and end? Given the matrixbasis from the InpoutOutput documentation:

Matrix:TwoDimension, !- matrix for basis definition
CFS_Glz_1_Basis, !- basis matrix name
9, !- number of rows
2, !- number of colums
0.00000, 1.00000,
10.00000, 8.00000,
20.00000, 16.00000,
30.00000, 20.00000,
40.00000, 24.00000,
50.00000, 24.00000,
60.00000, 24.00000,
70.00000, 16.00000,
82.50000, 12.00000;

I would guess:

• The zenith cone is 20 degrees wide (10° half angle).
• the next band is from 10 to 20 degrees with the normal.

• The said band has 8 x 45° patches

• The first patch in this band is from 0 to 45° azimuth (azimuth origin being defined as in the horizontal plane, on the west side if the normal is south) : p 24 in http://gaia.lbl.gov/btech/papers/3699...

• ....

• Last band is from 82.5° to 90° with 12 x 30° patches

Can anyone confirm?

Also, in what unit are these values in the 2d matrix of e+?

Finally, in case any experts are around or people who used this extensively, here are some more questions :)

Are there any other things i should consider using this approach?

How large can the matrix be to get reasonable runtime? (the study focuses on the window, everything around is rather minimalist: single room, adiabatic boundaries....)

Is it possible to have asymmetric matrices? (resolution on the sky side ... (more)