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OS Energyplus Processes Configuration

asked 2016-01-07 09:46:08 -0500

updated 2016-01-07 10:32:27 -0500


If using an IDF file with EP-Launch, there is the option to set the Number 0f Simultaneous Processes. When using OS to EnergyPlus, how is this value set/determined? Are the last settings from EP-launch used or are these overwritten in some fashion? Does anyone know where EP-launch saves this setting [some ini or cfg file location]?

The reason behind the question is that I am working on a very large CBECCcom file, which uses OS and EnergyPlus as part of its make up - and the simulation times are measured in days. This is not conducive to runs to test energy efficiency options or addressing warning/errors in the model. We experimenting with online cloud computing options [ie: AWS] and want to be able to 'unlock' the software to use the computing resource available. Any guidance on how best to configure and control something of this nature is greatly appreciated.

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answered 2016-01-07 10:26:52 -0500

updated 2016-01-07 10:30:37 -0500

That "Number of Simulation Processes" option you see in EP-Launch is NOT referenced if you run a single EnergyPlus Input Data file (#.idf). It is ONLY referenced if you run an EnergyPlus Group file (#.epg), which is really one large file that is a combination of multiple #.idf files. If you read more about these group files in the Auxiliary Programs documentation, you can create a #.epg file using a wizard that allows you to select multiple #.idf files to combine. This wizard also allows you to choose multiple weather files to use, in case your analysis requires different locations.

OpenStudio DOES NOT reference this "Number of Simulation Processes" option, since it doesn't have the capability of running simultaneous simulations. That's what it's "sister" program Parametric Analysis Tool (PAT) is for. Using PAT requires the application of measures to a baseline OpenStudio model, where you can then combine measures to form different simulation cases to compare to the baseline.

You can read more from a similar Unmet Hours question about parametric EnergyPlus simulations HERE.

When simulation time reaches multiple days, I'd seriously look into simplifying the model. You can reduce envelope heat transfer calculations by combining window surfaces (as long as you're not worried about accurate daylight modeling) and by using an area-weighted average U-value for a large opaque surface that represents combination of multiple opaque surfaces. As long as the overall heat transfer properties are the same (UA, h, absorptance, etc.) EnergyPlus will calculate heat transfer the same. Once the envelope has been simplified, the next place to analyze is the number of zones in the model and if they can be combined in any way.

If you are checking errors, it may help to run the design / sizing period(s), and then use the weather file to run 2-3 weeks around the design day(s) instead of the entire year. This will really shorten simulation time and give you results around times when errors are likely to occur.

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EP-Launch will take advantage of the "Number of SimultaneousProcesses" and run multiple instances of EnergyPlus when using Group files OR when just selecting and simulating a series of individual files from the main "single input file" tab. Either way you are running several different input files simultaneously not making a single input file run faster by using more computer processes.

JasonGlazer gravatar image JasonGlazer  ( 2016-01-07 10:51:23 -0500 )edit

Aaron, Thanks for the info on the simultaneous processes, did not realize it didnt work on single idf. Simplification is part of the issue. The model has already been greatly simplified with combined windows and surfaces as appropriate. Construction have also been simplified/unified as well. The are also no repeating floor plates or adjacent zones that have not been combined already. Area of the model is well over a million sqft conditioned area. I have beaten down on the errors, such that the model will run, but am needing full annual simulation data at this point....[continue below]

dradair gravatar image dradair  ( 2016-01-07 11:01:38 -0500 )edit demonstrate compliance. with all of this said - are there any other configuration settings or other steps that can be taken to make full use of powerful cloud servers? Or, is the bottleneck something inherent to how EnergyPlus operates?

dradair gravatar image dradair  ( 2016-01-07 11:03:46 -0500 )edit

@JasonGlazer, thanks for clarifying on simulating series of individual files as well. @dradair, wow that's a huge model! I would think a model that size will run slow regardless of simulation tool. In PAT, you have an option to run simulations on Amazon EC2, which requires setting up a payment account. If you can't get your final model from CBECC-Com into OpenStudio as a baseline point to use in PAT, you can try Autodesk's EnergyPlus Cloud.

Aaron Boranian gravatar image Aaron Boranian  ( 2016-01-07 11:31:14 -0500 )edit

You might also want to look at

JasonGlazer gravatar image JasonGlazer  ( 2016-01-07 11:35:20 -0500 )edit

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Asked: 2016-01-07 09:46:08 -0500

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Last updated: Jan 07 '16