Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Assuming this switch corresponds to the "-u" option in Radiance, it rarely makes a big difference. If you are generating images (i.e., using rpict), then the default is "off", and if you are calculating illuminance quantities and the like (i.e., using rtrace), then the default is "on". I would generally stick with those defaults.
