That room is a mansion compared to what I rock, but nonetheless you need to answer a few questions for yourself:
1. How much do you want/need to grow? A room that size is commercial. I use 250W for 6 square feet you have over 20 times that.
2. Can you do construction where this room is (rented or owned), i.e.- to run a perpetual cycle in that room you will need separate spaces with no light leak if you are doing veg and flower in the same room there will be light leak unless there are walls or barriers.
3. Can you handle the responsibility of never letting anyone in that room and fielding questions about why it is always locked and sounds like a fan store behind the door, lol.
If you are down with those questions I would say that a 12x12 room could sustain a great amount of flowering clones under a few 1000+watt HID lights and some serious ventilation and scrubbing systems. In the end that is a large space and will suck a lot of power to use it correctly. You would also need dedicated circuits if you were going to go big in that room. If you are a noob it might be a lot to get involved with at the start. You can always start small with a 400 or 600 system hanging in the room directly over the plants and then build a little veg/mother chamber with CFL's and then get bigger as your skill and wallet grow.
Just my 2 cents,
Best of luck!!