About Variable Air Volume Systems

Variable Air Volume (VAV) systems are one of the most common HVAC systems used in large commercial buildings. One reason is that VAV systems can easily accommodate high demand in one area and low demand in another, delivering comfort for everyone.

VAV systems work by providing a variable amount of airflow throughout a series of ductwork to service the needs of multiple diverse spaces. At the end of the ductwork, the conditioned air passes through a VAV box. As the air reaches the VAV box, a damper modulates the airflow necessary for each space to satisfy the zone cooling setpoint. VAV boxes serving spaces requiring mechanical heating are equipped with a reheat coil that uses hot water to warm the air supplied to the space and satisfy the zone heating setpoint. Chilled water is often produced by a chiller. In a typical VAV system, hot water is provided by a central gas boiler or air-source or ground-source heat pumps.

Advantages of VAV Systems

• Precise temperature control

• Can handle large amounts of ventilation air

• Quiet operation

• Easy to design and install in a new facility

• Long system life and simple to maintain

Disadvantages of VAV Systems

• Expensive to retrofit into an existing building

• More complex to control and operate properly

• A large amount of ductwork is necessary, which increases the first-cost significantly