Mesh lightning with directional light


I use a 3D Model as a building. You can go inside. There is a directional light to simulate the moonshine outside. Cast and recieve shadows are both activated.
it seems, that the lightning from outside affects the interior lightning, too.

Here an example:

This is how a enterable mesh looks from inside without lightning. (There is a ceiling)

This how it looks with lightning turned on.

Why is the floor not dark?

The walls behind the camera (not visible here) are brighter then the
walls in front of me. Is there a trick to tell unity, that a material
should not be affected by a directional light?
I dont want to use layers, because the outside of the building should be affected.

Why is there a black circle on the floor? It vanishs when u are far enugh away.

I am a bit confused and hope someone can enlighten me.


Thanks Snake for the tipp.
I solved the rest of the problem by myself. The mistake was to set the shadow intensity not to the maximum. If you dont use the max geometry lightning will become strange.