VAV stands for Variable Air Volume, which is a type of heating, ventilating, and air conditioning (HVAC) system. VAV systems supply air at varying levels or volumes to meet the heating and cooling loads as well as the ventilation rates required by the space. The primary goal of VAV systems is to provide comfort to building occupants and maintain healthy and safe air quality and space temperatures. VAV systems are more energy-efficient than constant air volume (CAV) systems because they vary the airflow at a constant or varying temperature, which reduces compressor wear, lowers energy consumption by system fans, and produces less fan noise.

A VAV system consists of an air handling unit (AHU) and VAV boxes, typically with one VAV box per zone. Each VAV box can open or close an integral damper to modulate airflow to satisfy each zone’s temperature setpoints. VAV boxes are pressure independent, meaning they use controls to deliver a constant flow rate regardless of variations in system pressures experienced at the VAV inlet. The VAV terminal unit, also known as a VAV box, is the zone-level flow control device that is connected to either a local or a central control system.

In summary, VAV in HVAC stands for Variable Air Volume, which is a type of HVAC system that supplies air at varying levels or volumes to meet the heating and cooling loads as well as the ventilation rates required by the space. VAV systems are more energy-efficient than CAV systems and consist of an AHU and VAV boxes, typically with one VAV box per zone. Each VAV box can open or close an integral damper to modulate airflow to satisfy each zone’s temperature setpoints, and VAV boxes are pressure independent.