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How to integrate Energyplus slab pre-processor into Openstudio?

asked 2014-10-14 10:22:34 -0500

Xandrika gravatar image

updated 2015-07-11 18:54:32 -0500

As I have learnt from other source, using the slab preprocessor of Energplus is essential to get the correct ground coupling. I am modeling with Openstudio and would like to know if I can automate that functionality (e.g. by writing a measure) in order to use it within Openstudio and its Parametric Analysis Tool. Maybe someone has already written such a measure and could share with me. I am new to Openstudio and Energy+ and understood the logic of the slab program. But I am not an experienced energy+ programmer. So I am not sure how to implement it. Thanks a lot. Regards, Susanne

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answered 2014-10-14 10:37:11 -0500

@Susanne/Xandrika. The just released EnergyPlus 8.2.0 integrates the slab pre-processor. If you cannot use this capability in OpenStudio 1.5.0, it should hopefully be accessible in an interim release.

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Thanks. Any idea when the next interim OpenStudio release will be out?

Xandrika gravatar imageXandrika ( 2014-10-14 11:52:43 -0500 )edit

Every two weeks

__AmirRoth__ gravatar image__AmirRoth__ ( 2014-10-14 11:55:01 -0500 )edit

You mean the pre-release here. How do I know what new feature/fixes/bugs have been implemented? I cannot find any release note.

Xandrika gravatar imageXandrika ( 2014-10-14 12:03:50 -0500 )edit

@Xandrika, the so-called pre-release versions--also referred to as "iteration releases"--are essentially snapshot builds of the OpenStudio source code, prepared bi-weekly, and as such the team does not prepare release notes for these. See this link for a chronologically-sorted list of closed issues. Also FWIW, the entire release notes history can be viewed here

rpg777 gravatar imagerpg777 ( 2014-10-14 15:58:06 -0500 )edit

In the meanfile, planned openstudio features and roadmap can be found here.

Xandrika gravatar imageXandrika ( 2014-11-24 06:28:11 -0500 )edit

answered 2014-10-15 13:35:58 -0500

OpenStudio 1.5.0 does not have support for EnergyPlus 8.2. I don't have a timeframe for when we will add support for 8.2, but in the mean time if you want to use slab and basement calculations in OpenStudio I did just push a few new measures to the Building Component Library. They are EnergyPlus measures that uses the slab and basement pre-processor to calculate ground temperatures. While not the exact same functionality you get in EnergyPlus 8.2 it will give you much of that functionality. Below is a link to the measures. If you search BCL from the OpenStudio application you will find this under "Envelope/Opaque" in the tree.

Slab and Basement Search on BCL

While most of the AEDG measures only require OpenStudio 1.3 or later, this one does require 1.5. Here is a screenshot. The two that currently exist are for school and office and have hard coded inputs for soil conditions, and use the AEDG guidance for slab conditions. You could adapt it to be a more generic slab or basement measure with all inputs exposed.

image description

Another approach if you want to use EnergyPlus 8.2 today is to export to an IDF from the file menu in the OpenStudio application and then use tools that ship with EnergyPlus to upgrade it to an 8.2 file to add features unique to 8.2. This is of course not an ideal workflow but may still be useful.


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I run further tests and found out that another model with a square form slab is running when I put the slab area to perimetre ratio in SI units (m2/m). I guess as the model is created in SI units, the ratio should be also in SI unit. Is this right? However, my original model (see above) is not working yet, even if I put the ratio in SI units?

Xandrika gravatar imageXandrika ( 2014-11-16 00:07:06 -0500 )edit

Another question came up: My model location is Pokhara (Nepal) which is not categorized in ASHRAE climate zoning. So, I calculated HDD18 and CDD 10 and found out that the location falls in ASHRAE climate zone 2. However, I do not understand why climate zone is important for ground temperature?

Xandrika gravatar imageXandrika ( 2014-11-16 00:18:52 -0500 )edit

Thanks a lot David, for the answer. However, the AEDG measure is not working properly with my model. Simulation is failing with the following problem: My input are: and my model looks like that ..and uses der OS SmallHotel Template.

Without applying the AEDG measure the simulation was running fine.

Xandrika gravatar imageXandrika ( 2014-11-21 11:17:36 -0500 )edit

Look at the eplusout.err file. This Link shows you where to find it.

David Goldwasser gravatar imageDavid Goldwasser ( 2014-11-21 14:59:43 -0500 )edit

@David Goldwasser I found the the log file you mentioned but don't really understand: Can you give me any advice? Thanks. There are 3 SEVERE errors: * Severe * BuildingSurface:Detailed="SURFACE 1", invalid Outside Boundary Condition Object="". * ~~~ *no OtherSideCoefficients of that name. SURFACE 1,8, and 15 have ground contact: I did another try with a rectangular building typ 10x10m base on small office template and there the meaure is running fine. I compared both OSM but cannot see any difference.

Xandrika gravatar imageXandrika ( 2014-11-23 09:24:36 -0500 )edit

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Asked: 2014-10-14 10:22:34 -0500

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Last updated: Oct 15 '14