Although at one point I was thinking about making a Maxwell's Demon SCP, this incarnation wasn't it (One idea was literally a cave in which an imp literally let air pass based on relative speeds). If Maxwell's Demon was used, there would have to be two areas, one for hot to be on, and one for cold. What actually inspired this was SCP-004, SCP-682, SCP-914, and a few others. Over the past few months, it has had massive mental revisions.
004 - I always thought it would be better if the green monster was not depicted, and instead that info was always just missing. 004 is good IMO, but a hole would have made it more interesting to me.
682 - Specifically, that it is neither organic nor inorganic, and infinitely adaptable. I'm not making a 682 killer in any way shape or form, but the idea of it being either, both, and neither all at the same time made me think of how scp's that interact with both organic, and inorganic matter simultaneously, would interact with something that is both and neither at will.
914 - I tend to like impersonal SCP's best. Ones that do something to an input, but cant be observed until opened. I have always thought of 914 as Schrödinger's SCP on crack. Until the output is observed, you have a quantum event inside where the object follows conservation of matter and energy, but is reconfigured in crazy ways. As such, I thought of something that is the other end of the spectrum…
Also I wanted a room sized SCP to not have a facility built around it, and instead be movable.
What if an SCP drops objects to Absolute Zero? More importantly, what if an SCP can drop objects to true absolute zero? Absolute Zero is a state in which matter has no movement, but Heisenberg's principal basically says that the electrons cannot stop, as when observed, we cannot know where they are, or a mess of physics breaks down. So what if the SCP prevents true observation at 0K?
To answer your big questions, everything in the room is cooled in a "uniform" fashion. If I could find a good way to build on the idea, think of no cooling ever happening at all in this freezer. Instead it slows everything on a sub molecular level. A person, an ice cube, and plasma would reach the same temperature in the exact same amount of time.
Mass loss is not directly related to the cooling effect, but in all but the last case. The last case, it is related to the fact that an observer can't be in the room. Other questions that are dangerous to answer is, what if a sapient inorganic is in the room? What if a clairvoyant observes the room from outside? Those are dangerous experiments, and yes I know what would happen, but I don't think SCPF would be inclined to necessarily test.
As I said, I would need help writing up experiments, if those would help, as that is not my forte'.
PS. Imp statue, in cave, only allows "cold" air past. When you walk past, all your warm air is forcibly ripped out of you.