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OpenStudio simulation fails when adding HVAC system

asked 2018-07-10 09:21:05 -0500

mdewey gravatar image


When I try to use the premade HVAC systems (or any type of premade system), and apply thermal zones to it, it always causes my simulation to fail.

I have set up HVAC systems to mimic what other people have successfully run, so I have no clue to what is causing the failure exactly.

I am guessing the solution is simple since I am new to Openstudio/EnergyPlus/Sketchup.

Thanks, for any help,


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Have you checked the error file for the simulation? If you click the 'Show Simulation' button on the top-right corner of the Run simulation tab, you will open the folder that contains the error file. It should be eplusout.err

Saroop gravatar imageSaroop ( 2018-07-10 19:56:06 -0500 )edit

Here is part of the text. Seems to be something to do with sizing?

* ~~~ * For explicit details on each unused construction, use Output:Diagnostics,DisplayExtraWarnings; * Severe * For autosizing of AirTerminal:SingleDuct:Uncontrolled AIR TERMINAL SINGLE DUCT UNCONTROLLED 1, a zone sizing run must be done. * ~~~ * No "Sizing:Zone" objects were entered. * ~~~ * The "SimulationControl" object did not have the field "Do Zone Sizing Calculation" set to Yes. * Fatal * Program terminates due to previously shown condition(s).

mdewey gravatar imagemdewey ( 2018-07-11 07:21:56 -0500 )edit

Did you add design days to your simulation? You are asking EnergyPlus to size equipment for you, but not giving it the information it needs to perform the sizing.

mdahlhausen gravatar imagemdahlhausen ( 2018-07-11 14:28:38 -0500 )edit

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answered 2018-07-11 10:47:09 -0500

Saroop gravatar image

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You can change the zone sizing option there.

Maybe this link will help?

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Got it! I turned on the sizing, and then also uploaded a design day file.

Would you be able to explain what a Design Day is? I just used one of the samples...

mdewey gravatar imagemdewey ( 2018-07-11 13:51:46 -0500 )edit

design days are days when you are expected to hit heating or cooling extremes. These are meant to be the 0.4% or 99.6% hours for outdoor weather variables, usually dry bulb temperature. EnergyPlus will do a sizing run to set equipment sizes based on the weather extremes in the design days.

mdahlhausen gravatar imagemdahlhausen ( 2018-07-11 14:30:15 -0500 )edit

If you did not use design days, shouldnt it just take the most extreme weather from the weather file to size the equipment?

Or is it not capable of doing this?

mdewey gravatar imagemdewey ( 2018-07-12 10:46:21 -0500 )edit

no, you have to specify design days

mdahlhausen gravatar imagemdahlhausen ( 2018-07-12 13:55:33 -0500 )edit

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Asked: 2018-07-10 09:21:05 -0500

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Last updated: Jul 11