How Direct Expansion Air-Conditioning Achieves Performance Goals For most of the A / C market, refrigeration-based ( DX ) cooling is the standard, and provides a point of comparison for new technologies. To describe the benefits and improvements of DEVap A / C technology, we must discuss standard A / C. Standard A / C reacts to SHR by cooling the air sensibly and, if dehumidification is required, by cooling the air below the dew point.