DCN October 2016 - Page 33

cooling most effective way to cut energy consumption in a data centre without affecting its main operations. Free cooling or economy mode is a common technique for using cold air coming from outside the data centre to cool the interior directly so that chillers can be temporarily switched off or run down. There are two distinct options to consider, namely direct and indirect air economisation. Direct (or fresh) air economisation draws a certain amount of cold outside fresh air through filters and then directly into the data centre when the outside air conditions are within specified conditions or set points. This system uses dampers to control the amount of hot exhaust air that is exhausted to the outdoors and mixed back into t