VRF (variable refrigerant flow) systems were first introduced in 1982 but have only been utilized in the United States since the early 2000’s. A VRF system varies and controls refrigerant flow through evaporator coils, providing temperature control to single or multiple zones. This type of system is commonly used in office buildings, schools, hotels, etc. and are perfect for existing buildings where there is not ceiling space for ductwork.
By their nature, VRF systems are not purposely designed for ventilation, so they are often paired with a DOAS (Dedicated Outdoor Air System) in a decoupled design. The VRF system will handle the sensible load (heating/cooling) while the DOAS unit will provide the proper ventilation rates required per ASHRAE 62.1 and handle the latent load (moisture removal).
When designing VRF Systems, Brucker offers the perfect pair through GREE and Greenheck products. GREE provides the outdoor unit, indoor unit, and controls while Greenheck provides the DOAS unit.
For more information, see this PDF.