The VAV system cost, assuming a water-to-air system, is usually higher than comparable unitary air systems (air-to-air) due to water loop piping, pumps, chiller (compressor), and possibly cooling tower, first cost. These costs are partially offset by construction (less space needed for a water pipe versus an air duct) and fan energy (less duct work needed to move air). The economics for these systems is complex, even for VAV air-to-air (i.e., no water loops). Read available literature for more insight.