our building is 60 x 120 - 7200 sq.ft.
our humidifier is a Fogco. Basically a big mister thas shoots "atomized"' water out of nozzles.
we dont run it at night. in the morning we come in, the humidity is around 10-15%. It runs about 10 minutes and the humidity goes up to what we set it, around 50 or 60%. Once it hits the mark, it runs about 3-4 minutes 2 or 3 times an hour to keep it there.
got it about 5 years ago. was around $5,000 plus another $1,000 to get a purified water system installed.