Question-and-Answer Resource for the Building Energy Modeling Community
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For EnergyPlus, the ZoneHVAC:LowTemperatureRadiant:VariableFlow object and ZoneHVAC:LowTemperatureRadiant:ConstantFlow object would the closest thing to BEKA capillary tube mats (no model objects match this scenario exactly). These can be assigned to any type of surface (floor, wall, ceiling), and can have a connection to both hot water and chilled water. You can search for energyplus radiant to review other posts on this topic.
Your comment about cooling via convection (cooled air drops from the ceiling) is accurate in reality, but EnergyPlus is an energy simulation engine -- not a computational fluid dynamics (CFD) simulation engine. Understanding those airflow details would require using a tool like Ansys to perform such a simulation. If you are willing to do that, you could then use the CFD results for air temperature within the zone as an input to EnergyPlus using the Room Air Model that defines non-uniform temperature distribution of air in a zone. Without the room air model, EnergyPlus assumes that each zone is "well-mixed" and it's entire air volume is homogenous (at the same temperature & humidity).
For the air flow rate caused by convection cooling, that could be defined as a velocity schedule and applied to the People object assigned to that zone. This allows EnergyPlus to update the detailed thermal comfort outputs (PMV, PPD, etc.) for those occupants accordingly.
Other than that, EnergyPlus can also alter the calculation approach for convection coefficients on the interior side of surfaces. This can be done with one of the options of the SurfaceConvectionAlgorithm:Inside object or by applying your own convection coefficients using the SurfaceProperty:ConvectionCoefficients object. It sounds like you want to use the algorithm approach with the AdaptiveConvectionAlgorithm option, which should use the Karadag algorithm for in-ceiling cooling by default (see below from the Engineering Reference).
You can also customize what algorithm is applied to different surface types using the SurfaceConvectionAlgorithm:Inside:AdaptiveModelSelections object.
