[dylan604]

Closed loop water systems is a common form of cooling in large/commercial buildings. Typically, a large chiller unit on the roof with the cold water piped throughout the building connected to individual blowers. I've been told it is much more cost efficient.

If that's not how they are using the water, then what are they using it for? Swamp coolers?

[quickthrowman]

Adding an evaporative cooling tower to a chilled water loop can up the COP to 7ish, an air-cooled chiller by itself maxes out around 4. It’s almost twice as effective at removing heat.

Air cooled chillers are fine for a commercial office building or tip-up warehouse, but data centers need to remove an enormous amount of heat.