Computer room air conditioners (CRACs) are similar to other air conditioning equipment but are intended to cool places such as computer rooms, server rooms, and data centers. CRACs are often referred to as “precision cooling” equipment. While most air conditioners are designed to remove both heat and humidity, CRACs are designed to primarily lower the temperature of the room (i.e. they have high sensible heat ratios). Some computer rooms and data centers utilize separate equipment for controlling humidity. CRACs can be air-cooled, water-cooled, or glycol-cooled.
The 2010 version of ASHRAE 90.1, which is a commercial building energy code, established a new equipment class for “air conditioners and condensing units serving computer rooms.” This action triggered DOE to set standards for CRACs. In 2012, DOE adopted the ASHRAE 90.1 efficiency levels as national standards, and they took effect in 2012 or 2013, depending on the specific type of equipment.
The standards for CRACs are based on a metric called sensible coefficient of performance (SCOP), which is the net sensible cooling capacity (in kW) divided by the power input (in kW).
Technology options for improving the efficiency of CRACs include higher-efficiency compressors, fan motors, and expansion valves and improved heat exchangers.