
Return air temperature control aims to achieve a constant ambient temperature within the room by varying the temperature of the air being supplied by the individual cooling units. This often results in a significant variation of the temperature of the air being supplied to the IT equipment, a variation which is out of the hands of the facility or IT manager. Controlling the temperature at the supply side of the air handler, rather than the return, gives control back to the facility manager and makes the temperatures being supplied to servers much more predictable. This predictability leads to the potential for raising water temperatures and reducing running costs as well as savings in capital costs during the construction of new facilities.
This paper uses a Virtual Facility to demonstrate the differences between the two control strategies and quantify the benefits of switching to supply side control.







