In the same way a room becomes conscious the moment a person walks into it.
So, to use your example, a room with a conscious person in it, considered as one whole, is at the very least partially conscious, since the person in it is conscious. Whether the room itself is conscious we don't quite know.
But this leads to the question: does the notion of "partially conscious" make sense?
1. a room and a person in it are separate
2. nothing is separate from the universe
Therefore, there are two things that are not separate from the universe but separate from each other.
Indeed separation is matter of consciousness. If we believe that the universe is more or less a frothing foam of energetic particles, the only thing that differentiates my teeth from my gums and me from the room is my recognition and identification of them. There is matter with or with out me, but there is no room, no tooth, no me without my consciousness.
"Particles" is plural, implying separation. It that, too, a "matter of consciousness"? Sounds a lot like "consciousness" is being used to do a lot of passing of the proverbial buck.
https://www.youtube.com/watch?v=vA3NLyQNDBQ
Another way to look at it:
https://www.youtube.com/watch?v=JEunth9YCgo (You are the Big Bang)
Why does the presence of a person in a room make a difference, as opposed to any other relationship between the two things?