There are many ways to cool data centers. The choice you make depends on the size, computer capacity that must be cooled, regional energy costs, and data load and density. Options for cooling data centers include:
Data center operators weigh the options and look for systems that reduce operating costs and environmental impact. They pay close attention to power use effectiveness (PUE), which is defined as the ratio of the total amount of energy used by a data center to the energy delivered to the computing equipment. A PUE of 1 means the heat rejection power equals the power used for the computing equipment. Data center operators are also concerned about water use effectiveness (WUE). Cooling towers evaporate water, but the impact depends on location.