Lighting properties of an enclosed room?

[Rapsheba555]

So we all know that a room will be lit differently than a non-enclosed space, especially during night. In an actual room, this has to do with the ambient lighting settings. What I would like to know, if anyone cares to guess, what would the ambient light of an enclosed room at night be equal to in emissiveness? Put another way: If I wanted to make something appear as if it were in an enclosed room at night with no lights on, what emissiveness level should I use to simulate the slightly brighter lighting of the room? (as opposed to the standard night lighting of "outside")

Hopefully that makes sense. :) Thanks in advance.