Typically used adjectivally to describe equipment for performing heating, ventilation and air conditioning tasks, or the rooms which house such equipment, or the technicians who service such equipment, etc.
hvac - Computer Definition
(Heating Ventilation Air Conditioning) In the home or small office with a handful of computers, HVAC is more for human comfort than the machines. In large datacenters, a humidity-free room with a steady, cool temperature is essential for the trouble-free operation of hundreds or thousands of servers. See server farm.