Owner: Both
To make buildings and units - you need money.
To repair buildings and units - you need money.
This whole game is based on money (well, some of).
Your Ore Miner brings all the money it collects into here.
If a spy will infiltrate into your ore refinery, he will steal money from it.
If your ore refinery will get destroied, you'll lose all the money in it.

The following video provides you with the correct English pronunciation of the word "Ore Refinery", to help you become a better English speaker.