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How to run EnergyPlus measure with user input in OpenStudio?

asked 2021-05-04 13:11:37 -0500

eva's avatar

updated 2021-07-09 17:47:35 -0500

Hi, I have a problem with running an EnergyPlus measure in OpenStudio. (I'm trying to run the FanMotorEfficiencyFault measure from the online BCL library.) I obtain the following error:

Initializing workflow. Processing OpenStudio Measures. Translating the OpenStudio Model to EnergyPlus. Processing EnergyPlus Measures. Applying FanMotorEfficiencyFault Result: Fail Initial Condition: Imposing airflow restriction on Fan:VariableVolume. Error: Measure FanMotorDegradation cannot find Fan:VariableVolume. Skipping...... Failed.

I'm working with an OSM file generated from an IDF file. This IDF file contains only one fan:

Fan:VariableVolume, Supply Fan 1, !- Name Always On Discrete, !- Availability Schedule Name 0.7, !- Fan Total Efficiency 600.0, !- Pressure Rise {Pa} autosize, !- Maximum Flow Rate {m3/s} Fraction, !- Fan Power Minimum Flow Rate Input Method 0.25, !- Fan Power Minimum Flow Fraction , !- Fan Power Minimum Air Flow Rate {m3/s} 0.9, !- Motor Efficiency 1.0, !- Motor In Airstream Fraction 0.35071223, !- Fan Power Coefficient 1 0.30850535, !- Fan Power Coefficient 2 -0.54137364, !- Fan Power Coefficient 3 0.87198823, !- Fan Power Coefficient 4 0.000, !- Fan Power Coefficient 5 Main Heating Coil 1 Outlet Node, !- Air Inlet Node Name VAV Sys 1 Outlet Node; !- Air Outlet Node Name

I'm entering the input arguments via the 'Edit' pane on the right hand side of the 'Measures' tab in OpenStudio. I've tried multiple things including the name of the fan (i.e. 'Supply Fan 1') and '* ALL Fan objects *' as indicated the displayed info for the given argument. (Info: "Enter the name of the faulted Fan:ConstantVolume, Fan:OnOff object or Fan:VariableVolume. If you want to impose the fault on all fan objects in the building, enter * ALL Fan objects *.")

I assume that there is no fault with the measure downloaded from BCL and that I'm doing something wrong... Please, can you advise me how to reference the EnergyPlus fan object to be used as input argument of the E+ measure?

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answered 2021-05-05 07:39:32 -0500

Craig Simmons's avatar

OpenStudio definitely does not recognize HVAC components when you import an IDF. Primarily it only imports the geometry and loads. If you haven't edited the model after importing the IDF you will not have HVAC systems. The error is simply telling you it did not find any Fan:VariableVolume objects.

There are measures that can insert a generic HVAC system for you, but if you intend to keep working in OpenStudio I would recommend reviewing the imported model in OS before throwing more measures at it. Alternatively there are ways to script changes directly onto an IDF file, but I'll admit that's not my expertise.

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answered 2021-05-05 06:41:31 -0500

mattkoch's avatar

I believe this might have to do with how OpenStudio converts (or reverse translates) IDF to OSM, namely with moderate success, especially anything HVAC. The fan may not have “materialized” in OS at all. Check the HVAC tab and see what systems, if any, show up. If you can’t find your fan there, then the measure is bound to fail.

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Asked: 2021-05-04 13:11:37 -0500

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Last updated: May 05 '21