During the day I took a couple of shots of one of the lecture theatres I look after.
The lights were down and the only sources were at the the rear of the room and the occasional spot light in the ceiling. I used the 14-42mm Panasonic lens shooting at around 4 seconds per shot at f5.6 using 200 ISO.
I took a couple using 30 second exposures but they were too freakin’ bright and clear. I wanted some darkness ergo the slightly quicker exposure. I might take a few more and set a smaller aperture to see if I can get a better depth of field, if in deed that is how it works of course!