Yes, VAV systems can be used in conjunction with other HVAC systems, such as radiant floor heating or chilled beams. In these hybrid systems, the VAV system provides the primary air supply, while the secondary system provides additional heating or cooling capacity. For example, a radiant floor heating system can provide supplemental heat to a zone during extreme cold weather, while the VAV system maintains a consistent air temperature. These hybrid systems can provide improved comfort, energy efficiency, and flexibility in commercial buildings.