Wall radiation fluxes in LEONARDO and .nc file

All around LEONARDO 4 (and previous 2014)
Wanlu
Posts: 15
Joined: Wed May 02, 2018 1:24 pm

Wall radiation fluxes in LEONARDO and .nc file

Postby Wanlu » Mon May 18, 2020 1:37 pm

Dear ENVImet team,

I have a question about different variable items in LEONARDO and .nc file.
Regarding emitted (or reflected) longwave radiations by the wall, there is only one item in LEONARDO called "Wall: Longwave radiation emitted by facade (W/m2)". But in .nc file, there are three items called "XFac_WallLWEmitted", "YFac_WallLWEmitted", "ZFac_WallLWEmitted" respectively.

Could you please explain the difference between them? And what do the XYZ factors mean in .nc file?

Thank you for your time!

Best,
Wanlu

Tim
Posts: 1401
Joined: Mon May 15, 2017 3:46 pm

Re: Wall radiation fluxes in LEONARDO and .nc file

Postby Tim » Tue May 19, 2020 5:59 am

Hi Wanlu,

For all wall parameters there are 3 output variables in NetCDF instead of one in Leonardo. Those values are saved for each facade direction individually (facades in X, Y, and Z direction).

Best regards,
Tim

Wanlu
Posts: 15
Joined: Wed May 02, 2018 1:24 pm

Re: Wall radiation fluxes in LEONARDO and .nc file

Postby Wanlu » Tue May 19, 2020 8:22 am

Dear Tim,

Thank you for your reply.
Whether the value in LEONARDO is a combination of values of three directions in NetCDF?
I checked in NetCDF file, one point has value in Xfactor, but is null in Yfactor and Zfactor. So I assume it picks one direction value only?

What is the definition of this direction? Does it measure the direction of the facade or the radiation (perpendicular to the facade)?

How to determine which direction a facade at an angle? i.e., when a facade is 45degree with respect to x-axis baseline? How about 30degree to x-axis.

Sorry for so many questions, as I am quite confused.

Thanks,
Wanlu

Tim wrote:Hi Wanlu,

For all wall parameters there are 3 output variables in NetCDF instead of one in Leonardo. Those values are saved for each facade direction individually (facades in X, Y, and Z direction).

Best regards,
Tim

Tim
Posts: 1401
Joined: Mon May 15, 2017 3:46 pm

Re: Wall radiation fluxes in LEONARDO and .nc file

Postby Tim » Tue May 19, 2020 10:13 am

Hi Wanlu,

Well, as we designed EDT output files for visualization in Leonardo, we could simply add the data for X, Y, and Z facades behind each other as binary data. Leonardo reads them like that because we designed that software and the reading procedures as well. So, one file holds X, Y, and Z data of each cell even if there is only a wall in Y direction for example. The only way we found for saving that in NetCDF is by creating an individual variable for each facade side. So every grid cell now has 3 representations as X, Y, and Z variable depending on the view direction of the facades that are available in a cell. If you think of a top corner of a building, data is available for all 3 facade directions: X, Y, and Z.

ENVI-met is based on rectangular grid cells. There are no 45° angles in facades. A facade is either perpendicular to X, Y, or Z.

Best regards,
Tim


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