I'm assuming you're looking for what is often called a Mini-Split Heat Pump which are typically ductless but can also be installed as ducted systems. As Julien mentioned, OpenStudio doesn't model ducts or duct losses so no need to explicitly model this feature of the system. Here are some suggestions based on building type:

Commercial Buildings

These types of systems are commonly found in secondary spaces, for example stairways and electrical rooms. Unless a large part of the building is conditioned by these systems you could use the ZoneHVAC:PackagedTerminalHeatPump as a simplification.

Residential Buildings

For this building type you could build custom air loops for them. For example, BEopt uses the following objects to model MSHPs:

• AirLoopHVAC:UnitaryHeatPump:AirToAir:MultiSpeed
• Coil:Cooling:DX:Multispeed
• Coil:Heating:DX:Multispeed
• Fan:OnOff

I'm assuming you're looking for what is often called a Mini-Split Heat Pump which are typically ductless but can also be installed as ducted systems. As Julien mentioned, OpenStudio doesn't model ducts or duct losses so no need to explicitly model this feature of the system. Here are some suggestions based on building type:systems.

Commercial Buildings

These types of systems are commonly found in secondary spaces, for example stairways and electrical rooms. Unless a large part of the building is conditioned by these systems you could use the ZoneHVAC:PackagedTerminalHeatPump as a simplification.

Residential Buildings

For this building type you could build custom air loops for them. For example, BEopt uses the following objects to model MSHPs:

• AirLoopHVAC:UnitaryHeatPump:AirToAir:MultiSpeed
• Coil:Cooling:DX:Multispeed
• Coil:Heating:DX:Multispeed
• Fan:OnOff

I'm assuming you're looking for what is often called a Mini-Split Heat Pump which are typically ductless but can also be installed as ducted systems.

Commercial Buildings