What is the definition of a VAV heating and cooling system? VAV stands for Variable Air Volume, which refers to the ability of the system to adjust the air volume that is entering the space. It is a type of heating and cooling system used in commercial and industrial buildings that is designed to optimize energy efficiency. It works by controlling the amount of conditioned air entering the space and adjusting the temperature and humidity of the air depending on the current needs. The VAV system is usually composed of two main components: a supply fan, which pulls in outdoor air, and a reheat coil, which adds heat to the air. Additionally, a VAV system will often include an air-handling unit, which is the main component that controls the air flow, temperature, and humidity. The VAV system is designed to reduce energy costs by adjusting the air flow and temperature as needed. The system can be programmed to provide the most efficient heating and cooling possible while still maintaining comfortable temperatures and acceptable air