Hi Alllesss,
There isn’t any bounds for the directional light so that wouldn’t work.
If you need different lighting for each window the only solution I can think that may work would be to test something with making each section it’s own level with the base level being your persistent. You can build lighting independently on these different levels and then have them combined to create your final result. When you do this you only the lighting available in that level that is visible will be baked.
This is a sample project I did using level streaming, but without the level streaming and just making both visible at the same time you can get something maybe. [TUTORIALS] Photons Be Free: Mini-tutorials and other curiosities - Community & Industry Discussion - Epic Developer Community Forums
I’m not sure if it’ll fully work depending on the situation, but it’s a place to start. Unfortunately, Lighting channels are not possible with UE4 like their were in UE3/UDK due to deferred rendering vs forward rendering.