[Radiance-general] clear sky-calculated indoor illuminance is too lower than that of cloudy sky???

[Lars O. Grobe]

So you get an mkillum-modifier for the window pane usinf esp-r. This
brings up another idea - are you sure that the surface normal of your
window points to the inside of the room? If there is an illum used for
the window, actually a 0-illuminance is strange even with very low
ab-settings.

CU Lars.