Hi all
I have noticed a discrepancy with Ecotect and its handling of Radiance Glass materials. You need to check your material in the relevant Radiance mat file before accepting analysis.
Essentially, if you set your transmittance to say 0.8 in Ecotect, the relvent transmissivity is not reflected in the rad material file. For example, when I export from Ecotect a glass transmittance of 80% 0.8 i get this material file description:
void glass SingleGlazed_TimberFrame
0
0
3 0.5460 0.5460 0.5460
I think this is wrong. According to the radiance website http://radsite.lbl.gov/radiance/refer/ray.html the transmissivity is calculated from the transmittance via this formula: tn = (sqrt(.8402528435+.0072522239*Tn*Tn)-.9166530661)/.0036261119/Tn
where Tn=Transmittance in this case 0.8 and Tn is transmissivity. Following that, my transmissivity for this example should be 0.87 and the material description thus:
void glass SingleGlazed_TimberFrame
0
0
3 0.870 0.870 0.870
Can someone at "Ecotect Control" confirm this?
Thanks
hello danatgia I think
hello danatgia
I think only the setup in reflectance can influence the radiance parameters,i guess the color of window in reflectance expresses the Red transmissivity,Green transmissivity and Blue transmissivity in radiance.
Another problem i don`t understand: The specularity in ecotect is 4 times than the specularity in the exported radiance files.
Your are right on
danatgia,
This has been a problem with ECOTECT for a while and seems to be still broken in version 5.5.
There is a work around, however. Select the "Check for Material.rad files" and then include simple text files that have the correct glass description. Each description needs to have the same file name as the you have named the material. For example, if you create a glass in the ECOTECT material definition file named "VE 1-2M" then create a text file named "VE 1-2M.rad"
Hope this helps...
KB
has this been fixed in v5.6
Hello,
I would like to know if these transmittance to transmissivity issues have been fixes on version 5.6?
When exporting the ecotect model to run Daysim, a window with transmittance value of 68% appears in the Daysim material file as:
void glass DoubleGlazed_AlumFrame_68_
0
0
3 0.7200 0.7200 0.7200
which doesn't fit the results for the formula mentioned in the first post.
Thanks for the reply,
Timo