Numerous decisions must be made in the design of computer air conditioning, each determined by a combination of economics, physical, and esthetic characteristics, and computer requirements. Several computer air conditioning systems are analyzed--(1) underfloor supply and overhead return, (2) underfloor plenum and overhead supply with computer unit having an internal fan to provide upward flow, (3) underfloor plenum and overhead supply with computer having an internal fan to provide downward flow, (4) overhead supply and ceiling return air plenum to serve upflow computer unit, (5) up and downflow computers served by underfloor plenum and overhead supply, and (6) room air conditioners. (RH)