Free cooling is a feasible economic method which utilizes outside, ambient air temperatures to cool the IT equipment. Free cooling can result in significant electrical cost savings, which results in a more favorable PUE (Power Usage Effectiveness). Because of this need for constant cooling, enterprise users as well as colocation providers consider free cooling as a metric for site selection.
There are three types of free cooling technologies depending on the mechanical infrastructure used to cool a data center. The most prominent is Air Side Free Cooling, which is where outside air is brought into the data center directly through the filters or indirectly through heat exchangers. Another is Adiabatic Free Cooling, where outside air is added with water evaporation to cool the air. The last is Water Side Free Cooling, where water circulates directly through cooling towers as opposed to chillers or compressors.