US Patent 8636565 Data center air circulation

A method for cooling electronic equipment can include flowing cooling air across a plurality of computer units and into a common warm air plenum located at a first end of the computer units; flowing air from the warm air plenum through one or more cooling units, and into an area located at a second end of the computer units; and controlling a flow rate of air out of the warm air plenum to maintain a predetermined pressure differential between the second end of the computer units and the first end of the computer units.