Thanks Fred, that is exactly what I did and it looks that there is no builtin component for split units. The alternative is to build a custom air loop by using the following objects:

AirLoopHVAC:UnitaryHeatPump:AirToAir:MultiSpeed

Coil:Cooling:DX:Multispeed

Coil:Heating:DX:Multispeed

Fan:OnOff

No split unit available in Open studio and EnergyPlus, and it's very hard to make your own model

Thanks Ahmed, So how do think I could do it?

Hi Samah, I found the following for you :

"EnergyPlus HVACTemplate:System:Unitary and HVACTemplate:System:UnitarySystem both can be used to model a split system or a rooftop system. HVACTemplate:Zone:PTAC is intended for a non-split through-the-wall type of system, but it can also be used. All three of these systems model essentially the same set of components and can apply to split systems or rooftop systems given appropriate efficiency and fan pressure inputs"

and another solution I found was

" use one of the zone HVAC systems (like PTAC) or use an AirLoopHVAC based system with a AirLoopHVACUnitary component inside of it to manage the cycling. OpenStudio does not support reconfiguring zone equipment graphically in the application, therefore you cannot graphically replace the water coil with an electric heating coil. Certainly this is possible with a measure but I'm going to assume that you would rather use the UI. So go the AirLoopHVAC route following these steps to build up a system from components."

Create a new empty AirLoopHVAC system.

Add an oa system

Add an AirLoopHVACUnitarySystem. You want the one with DX cooling, cycling, and electric "reheat", which will really just be heat in this case.

Attach your zone.

Add an uncontrolled terminal.

Edit the unitary system and make sure that the attached zone is specified as the Controlling Zone.

Check the following:

http://www.worldscientific.com/doi/abs/10.1142/S2010132514500060?journalCode=ijacr

or try another package like DesignBuilder Software (not free)

How to model a split unit air conditioner in Open Studio?

How to model a split unit air conditioner in Open Studio?