Before I built the fish house I had enclosed my garage but I found it too small for me...LOL. I would suggest against a central system. I had drilled all of my tanks so it really made wc's easy. Make sure you get a really good dehumidifier. Also Figure out how many electrical outlets that you think you will need and then double it. I had 1/2 of my outlets out 5 or so feet up on the wall to serve the upper tanks.
-john