Here is what I consider when deciding on a place for anything big and heavy: (not in any particular order)
1. continuity of concrete slab
2. blockage of doors or pathways (for moving future equipment)
3. proximity to electrical panel
4. heat/cooling sources near machine (AC vents, sunlight, etc)
5. convenience to operate
6. fire code
As for noise/electricity consumption, that depends on the machine and what you're doing with it.
Our machines are quite loud when roughing, but the roughing cycles don't typically last very long. I believe most of our electricity is being used for air conditioning and not the operation of the two machining centers.
I would say the size of your room is going to be advantageous with a single machine.