A LIF Light Guide of only 0.25 m² changes the illuminance throughout the room radically:

With an exterior illuminance of 40 klx the interior illuminance will be:
600 lx on the workplace near the window, 300 lx in the center of the room and 140 lx near the rear wall.

Without LIF the direct sunlight hits at a small area of the room and leads to an extremely high illuminance of about 27 klx which would cause strong glare on the work area.

The uniform illlumination of the room by LIF is the prerequisite for the optimal use of artificial lighting control dependent on the daylight level.