Question Changing Light (or Light Layer) Intensity with a Volume or similar possible?

Okay, this might be a quite unique problem:

I am using 2 Backlights which are only affecting my character to add some more style to them. My problem is as soon as they enter a building the backlights are way too strong and would need to be lowered in their intensity by quite a lot. Is there an easy way to get this effect with a script or anything, maybe even so that I can tie it to my interior volumes?