A Variable Air Volume (VAV) system controls the temperature in space by varying the quantity of supply air rather than varying the supply air temperature. A VAV terminal unit at the zone varies the quantity of supply air to the space. The supply air temperature is held relatively constant. Although supply air temperature can be moderately reset depending on the season, it must always be low enough to meet the cooling load in the most demanding zone and to maintain appropriate relative humidity. VAV systems can be applied to interior or perimeter zones, with common or separate fans with common or separate air temperature control, and with or without auxiliary heating devices. The greatest energy saving associated with VAV occurs in perimeter zones, where variations in solar load and outdoor temperature allow the supply air quantity to be reduced.

The VAV system uses outside air mixed with the return air at a central air handling unit and the air is heated or cooled depending on the needs of the space using chilled or heated water. The VAV system is typically very economical, especially on a large scale.

VAV systems are widely used for various types of buildings. Typically those buildings are large in volume that require individual temperature control. Few examples would be Arenas, Exhibition Halls, Theaters, Medium to large public office buildings and residential complexes.

For further control a VAV system is often paired with reheat coils or radiant units in a space. This enables fine temperature control and energy savings for projects.

Key strengths of VAV systems are:
a. The system is able to meet cooling loads without over or under sizing.
b. Variable air volume allows for smaller fan sizing producing energy savings.
c. Individual temperature control for different occupancy zones.

Cove.tool supports the following VAV systems:

Find out more about Variable Air Volume systems here.
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