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weather file vs design day file in openstudio

asked 2015-11-13 10:41:33 -0500

SVVitale gravatar image

updated 2017-05-29 17:49:03 -0500

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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answered 2015-11-13 11:29:17 -0500

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!

SVVitale gravatar image SVVitale  ( 2015-11-13 13:41:58 -0500 )edit

So is it possible that I only import a DDY file for system sizing but import no EPW file?

W. Chiang gravatar image W. Chiang  ( 2017-04-16 08:36:43 -0500 )edit

@W. Chiang, Yes. You can import DDY file for system sizing without the EPW file. You need to modify the SimulationControl object as follow:


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

Yixing Chen gravatar image Yixing Chen  ( 2017-04-17 19:51:39 -0500 )edit

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.

W. Chiang gravatar image W. Chiang  ( 2017-04-18 22:44:37 -0500 )edit

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Asked: 2015-11-13 10:41:33 -0500

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Last updated: Nov 13 '15