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# Is Slab compatible with Energyplus?

I am trying to calculate the entries for the Site:GroundTemperature:BuildingSurface object. However, Slab only generates in_slab.ger which appears to have an error for every object in the idf file. The first few errors are:

Program Version,GroundTempCalc - Slab, Version .75
** Severe  ** IP: IDF line~10 Did not find "Version" in list of Objects
** Severe  ** IP: IDF line~16 Did not find "SimulationControl" in list of Objects
** Severe  ** IP: IDF line~26 Did not find "Building" in list of Objects
** Severe  ** IP: IDF line~39 Did not find "ShadowCalculation" in list of Objects
** Severe  ** IP: IDF line~47 Did not find "SurfaceConvectionAlgorithm:Inside" in list of Objects
** Severe  ** IP: IDF line~53 Did not find "SurfaceConvectionAlgorithm:Outside" in list of Objects
** Severe  ** IP: IDF line~59 Did not find "HeatBalanceAlgorithm" in list of Objects
** Severe  ** IP: IDF line~66 Did not find "ZoneAirHeatBalanceAlgorithm" in list of Objects
** Severe  ** IP: IDF line~72 Did not find "ZoneAirContaminantBalance" in list of Objects
** Severe  ** IP: IDF line~78 Did not find "ZoneCapacitanceMultiplier:ResearchSpecial" in list of Objects
** Severe  ** IP: IDF line~89 Did not find "Timestep" in list of Objects
** Severe  ** IP: IDF line~95 Did not find "ConvergenceLimits" in list of Objects
** Severe  ** IP: IDF line~105 Did not find "Site:Location" in list of Objects


Does Slab still work with the current version of Energyplus? There seems to be a few UnmetHours posts on how to do without Slab. Just "yes" or "no" would be great! Just want to know if I should move on to something else.

POST SCRIPT:

Slab ran fine with 5ZoneAirCooledWithSlab.idf example file.

After a little experimenting, I was able to get my idf file to run slab by adding the following objects:

GroundHeatTransfer:Control
GroundHeatTransfer:Slab:Materials
GroundHeatTransfer:Slab:MatlProps
GroundHeatTransfer:Slab:BoundConds
GroundHeatTransfer:Slab:BldgProps
GroundHeatTransfer:Slab:Insulation
GroundHeatTransfer:Slab:EquivalentSlab


I also changed all the Outside Boundary Condition fields of Ground for my BuildingSurface:Detailed objects to

GroundSlabPreprocessorPerimeter,  !- Outside Boundary Condition


Currently I just copied-pasted the objects from the example idf file to my idf file and will have to read up on the objects to fill the fields appropriately for my model. But where is that documentation?

@JasonGlazer
I went through your links for using slab, but I couldn't find much description of the objects related to Slab. Then I looked in the Input Output Reference for Energyplus 8.9 and found this page,

but I couldn't find the GroundHeatTransfer:Slab:Materials object (I didn't search for any of the other objects in the list) anywhere else in the Input Output Reference using Cntl+f to search the pdf. I was able to find descriptions of the fields in the IDF editor, which seem good enough to use the objects.

However, I don't really know if all these objects are necessary for Slab to run, or how they interact, or what Slab does in the absence of one of these objects ...

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Yes.

The easiest way is to use Slab is with EP-Launch or RunEPlus.bat on Windows. Try running the 5ZoneAirCooledWithSlab.idf example file and you will see that it runs. I just tested it with EnergyPlus 8.9.0.

Slab is a preprocessor which, by itself, is tricky to use so it has been integrated with ExpandObjects (another preprocessor that is usually known for working with HVACTemplate objects). The objects used are documents here in the InputOutputReference and in the Auxiliary Programs documentation here [Note, you will have to use the "Next >>" button to see the rest of the pages].

It can also be run directly although a bit more complicated (see the .\PreProcess\GrndTempCalc subdirectory). The special IDF can be run using the RunSlab.bat file in that location and the pieces that it produces copied into a normal IDF file and then that IDF file run with EnergyPlus. It is easier to just use EP-Launch.

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@JasonGlazer Please see my edited post. In particular, is there more thorough documentation of Slab and its associated objects?

( 2018-06-19 16:42:21 -0500 )edit
1

More Slab documentation is in the Auxiliary Programs document.

( 2018-06-19 17:22:30 -0500 )edit

Does Slab still work with the current version of Energyplus?

Yes. The error messages indicate that you were running an EnergyPlus idf file with the Slab program. Running Slab alone requires a different input file with just Slab objects. In the EnergyPlus install folder, see PreProcess\GrndTempCalc\SlabExample.idf.

Just want to know if I should move on to something else.

Yes. Slab is useful, but it gives you static monthly temperatures as the outside boundary condition for the floor slab based on the specified monthly average indoor air temperatures in the slab input. If the EnergyPlus model results in significantly different indoor air temperatures, then the floor heat transfer will be wrong.

There are two newer integrated foundation heat transfer models available directly in EnergyPlus, each with their own strengths and limitations. See Site:GroundDomain:Slab and Foundation:Kiva.

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