Cooling load not sized correctly
I am a graduate student doing a research project comparing the energy use between standard DX/Gas units and ground source heat pumps for a low rise residential building. I have set up a three story, 18 unit, apartment building in open studio. Each apartment is created on its own thermal zone and is being served by the cycling PTAC DX Clg Gas Htg object. I need the total load for this building to size my geothermal well field, however, the outputs for the cooling equipment size are around 1/3 of a similar model ran in Trace 700.
I am wondering what I can do to more closely match the cooling load from open studio model to the realistic values or Trace 700 outputs to correctly size my geothermal field. I have read other posts similar to this one and I have tried their suggestions. Instead of using the cycling PTAC DX Clg Gas Htg, I have defined an air loop with a OS:AIRLoopHVAC:Unitary System and yielded the same results. I have also changed my windows from simple glazing to a BCL component with no success.
Any suggestions on this matter would be greatly appreciated.
@MEP Engineer you might want to start with ideal load to estimate the load. Would also make sure you used the right weather data file and the riight DDY data.