I have a 24' x 32' shop with white walls, floor and ceiling (15.5' height). I have (5) 400 watt low bay metal-halide lights with separate switches so I can light only as much as I need. With the doors (also white) closed, I normally use 1 light and at most I use 3 lights. With the doors open at night, I normally use 2 lights and once in a great while all 5. It is so bright that the people across the street have asked me not to turn them all on unless I close the doors.

It does take more effort to keep it clean though, especially the floor. I normally hose it down for about 15 minutes once a week; it stays pretty good the rest of the time.
