It’s usually open loop - closed loop, so closed loop goes through CRACs or liquid cooled equipment manifolds. That heated water circulates through an heat exchanger on the roof that uses open loop cooling to shed the heat to the surrounding environment.

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bozhark 5 hours ago | parent [-]

How inefficient

	▲	cl0ckt0wer 5 hours ago \| parent \| next [-]
		Way more efficient, that's why they do it. Evaporating water carries an enormous amount of energy.
	▲	quickthrowman 4 hours ago \| parent \| prev [-]
		It uses almost half as much electricity, it’s way more efficient than air cooled chillers by themselves. East of the 100 degree W line of longitude, there is more than enough water to use evaporative cooling if needed.