US Patent RE42195 Energy efficient crac unit operation using heat transfer levels

A method for controlling one or more computer room air conditioning (CRAC) units for energy efficient operation, in which, the temperature of the air returned (Trat) into the one or more CRAC units and the temperature of the air supplied (Tsat) by the one or more CRAC units is detected. The caloric heat transfer level (Q) is calculated based upon the Trat and the Tsat and it is determined whether the Q is within a predetermined setpoint caloric heat transfer range. In addition, at least one operation of the one or more CRAC units is reduced in response to the Q being within the predetermined setpoint caloric heat transfer range to thereby increase the efficiencies of the one or more CRAC units.