weather file vs design day file in openstudio
What are the purposes for EPW files and DDY files in energy plus and Openstudio? When to I choose to use one or the other or both?
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The DDY file is used for zone/system/plant sizing (design day simulation), while the EPW file (typically including hourly data for a year) is used for annual (a period) energy simulation.
The DDY file is in IDF format. You can copy and paste the objects in DDY file to IDF file.
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Thank you very much!
So is it possible that I only import a DDY file for system sizing but import no EPW file?
@W. Chiang, Yes. You can import DDY file for system sizing without the EPW file. You need to modify the SimulationControl object as follow:
SimulationControl,
Yes, !- Do Zone Sizing Calculation
Yes, !- Do System Sizing Calculation
Yes, !- Do Plant Sizing Calculation
No, !- Run Simulation for Sizing Periods
No; !- Run Simulation for Weather File Run Periods
Thank you. I have another question, what's the difference between zone sizing and system sizing? I created a building with a single zone, and the design sensible cooling load in System Sizing I've got is roughly two times the size of the design sensible cooling load in Zone Sizing.
This probably means you have a system serving multiple zones.
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