In general, there is no specific place to locate the machine room. But it is most logical to place it as close to the jack as possible. Reasons? If there is a leak in the oil line, less oil to drain, reduces number of 90's, less friction, run cooler. Electrical run shorter, not so much on the second floor but other remote, yes. Cheaper to install when next to hoistway. And in general Elevator mechanics prefer it next to it on the lowest level. My opinion only.
