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Does OS 2.2.0 write the ideal load air system object to IDF file after E+ measures are executed?

asked 2017-09-27 07:06:43 -0500

Avi's avatar

updated 2017-09-27 19:18:26 -0500

I am trying to use mdahlhausen's E+ Ideal Loads Options Measure. Trying to do so I had found out that the measure can't find any ideal load air object. When I look in the in.idf file I can find the ideal loads air objects at the end of the file under a comment saying "New objects created from ExpandObjects".

Is that true? Is there a way to get around that?

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Did you actually check the box under the thermal Zones tab to enable the Ideal Loads?

Julien Marrec's avatar Julien Marrec  ( 2017-09-27 08:53:14 -0500 )edit

Yes I did check that box

Avi's avatar Avi  ( 2017-09-28 15:57:30 -0500 )edit

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answered 2017-09-27 16:12:26 -0500

updated 2018-03-02 20:01:37 -0500

[Update March 2nd, 2018]:

The Ideal Loads Options measure is now available on BCL and on the Unmet Hours openstudio-measures Github.

If you want to run it for OpenStudio version <=1.14, there is a toggle in the measure.rb file to set it to edit ZoneHVAC:IdealLoadsAirSystem objects instead of HVACTemplate:Zone:IdealLoadsAirSystem objects.

The GitHub issue is closed, and the OpenStudio team will stay with the OS v2 series order of operations: EnergyPlus Measures -> Expand Objects -> Pre-Process

[Update October 5th, 2017]:

In OS v1 series, the order of operations is: Expand Objects -> EnergyPlus Measures -> Pre-Process

In OS v2 series, the order of operations is: EnergyPlus Measures -> Expand Objects -> Pre-Process

HVACTemplate objects, including HVACTemplate:Zone:IdealLoadsAirSystem objects, are translated into EnergyPlus objects (ZoneHVAC:IdealLoadsAirSystem objects) in the Expand Objects step.

This means EnergyPlus measures in OS v2.+ can't include any get calls to an object formed from expanding an HVACTemplate object because they don't exist yet.

The issue is that the workspace.getObjectsByType("ZoneHVAC:IdealLoadsAirSystem".to_IddObjectType) call in the measure script correctly returns ZoneHVAC:IdealLoadsAirSystem objects in OS v1.14, but returns an empty array in OS v2.2. The measure was written with OS v1.14.

I've submitted this as an issue. I'll update once I know more.

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As a side note, I'll rewrite my measure as a model measure and post it to BCL.

mdahlhausen's avatar mdahlhausen  ( 2017-10-05 12:40:55 -0500 )edit

answered 2017-10-05 04:39:18 -0500

Avi's avatar

It turns out that OS 2.2.0 implements Ideal load air system by creating a HVACTemplate:Zone:IdealLoadsAirSystem which in turn, using the ExpandObjects preprocessor program, translated into Ideal load air system object. That step is done AFTER the E+ measures are applied. More info can be found in the input/output reference of e+ page 2297.

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Thanks for the clarification. I've updated my answer above.

mdahlhausen's avatar mdahlhausen  ( 2017-10-05 12:39:03 -0500 )edit

answered 2017-09-27 09:42:11 -0500

EnergyPlus Measures are executed after any OpenStudio Measures are applied to the Model and the Model has been forward translated to IDF. If you checked the Ideal Air Loads boxes for Thermal Zones then they should be in the IDF that the EnergyPlus Measure is working on.

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Would that be the in.idf or pre-expand.idf or maybe the pre-preprocess.idf? Where can I find info about that process?

Avi's avatar Avi  ( 2017-09-27 12:27:44 -0500 )edit

Using workspace.getObjectsByType I can only find objects that are within pre-preprocess.idf which as far as I understand is the shortest of the three files.

Avi's avatar Avi  ( 2017-09-27 13:38:27 -0500 )edit

They are in the .idf. I just can't access them with the .getObjectsByType method in OS v2.+. This call does return the objects in v 1.14. Did the order of when EnergyPlus measures change in OS v2.+?

mdahlhausen's avatar mdahlhausen  ( 2017-10-05 11:58:16 -0500 )edit

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Asked: 2017-09-27 07:06:43 -0500

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Last updated: Mar 02 '18