Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Technically, you can specify as many "receiver" objects as you like in one run of rfluxmtx, in this case windows. You need to specify the output file ahead of each window polygon using the "#@rfluxmtx o=output.mtx" variable as described in the man page at https://radiance-online.org/learning/documentation/manual-pages/pdfs/rfluxmtx.pdf
The calculation will also be more efficient if you don't need to run it separately for each window. However, it is generally necessary to run rfluxmtx separately to calculate the external "daylight" matrix connecting each window exterior to the sky. The exception to this is when there are few nearby obstructions outside the building, and the windows all lie in a plane that you can assemble as a single "source," even though they may be physically separated by mullions or wall sections. Again, it will be more efficient to combine calculations when possible, but it is not required b the method.
The tutorial recommended by JChen remains the authoritative source.
Best, -Greg
| | 2 | No.2 Revision |
Technically, While it is true that you can only have one sender object per rfluxmtx calculation, you can specify as many "receiver" objects as you like in one run like; in this case, all of rfluxmtx, the windows in a given room. The sender in this case windows. You is replaced by your selection of points, as is normal for a view matrix calculation. To include multiple receivers, you need to specify the output file ahead of each window window's polygon using the "#@rfluxmtx o=output.mtx" the
#@rfluxmtx o=output.mtx
variable as described in the man page at https://radiance-online.org/learning/documentation/manual-pages/pdfs/rfluxmtx.pdf
The view matrix calculation will also be more efficient if you don't need to run can avoid running it separately for each window. However, it is generally necessary window in this way.
While you did not ask, you do need to run rfluxmtx separately once per elevation (i.e., direction) to calculate the external "daylight" matrix matrices connecting each window the building exterior to the sky. The exception to this is sky, since the sky (+ground) is in this case the only receiver. Normally, this means running rfluxmtx once per window. A shortcut is possible when there are few nearby obstructions outside the building, and the windows all lie in a plane that you can assemble as a single "source," "source" for that elevation, even though they may be physically separated by mullions or wall sections. Again, it will be more efficient to combine calculations when possible, in this way, but it is not required b by the method.
The tutorial recommended by JChen remains the authoritative source.
Best, -Greg
