# Re: [EnergyPlus_Support] Slab Programme

```Can the Slab Program be used with crawl spaces and a
combination of a crawl space and slab on the ground
floor?

--- "Michael J. Witte" <mjwitte@xxxxxxxx> wrote:
> Answers regarding questions about inputs to the slab
> program
> (\EnergyPlus\PreProcess\GrndTempCalc\slab.exe):
>
> > Surface Albedo: NO Snow/Snow?
>
> This will change the ground surface temperature by
> reflecting solar
> energy.  The Albedo is more commonly recorded than
> the absorptivity.
> The albedo can range from as low as 0.05 for
> blacktop surfaces to
> 0.95 for fresh snow.  Representative average values
> for North America
> are 0.16 in the summer and 0.40 in the winter.
> Ref:  Sellers,
> Physical Climatology, Univ of Chicago Press, 1965(
> from W. P.
> Bahnfleth, Ph.D. Thesis, University of Illinois,
> Mech Eng Dept,
> Urbana, IL, 1989)
>
>
>
> > Under slab insulation: What does such a insulation
> look like as
> > the next field in the object depicts the width of
> strip of
> > insulation.
>
> This is a layer of horizontal insulation of the
> width and thermal
> resistance specified underneath the slab all around
> the perimeter.
>
>
> > The area to perimeter ratio for this slab: this
> term is
> > self-explaining, but in the example idf-File
> > (Slab2x2VertInsMplsAP10) this ratio is 10- the
> specified dimension
> > of this slab is 12x12.
>
> The example uses the EquivSlab and EquivAutoGrid
> options.  Thus the
> input in the AutoGrid object is not used.  The A/P
> ratio of 10 is
> used.
>
>
> > Thickness of slab on grade?
>
> This specifies the floor slab thickness.  It is used
> in conjunction
> with the "Slab k" field to determine the thermal
> resistance of the
> slab.  This and the specified temperatures and heat
> transfer
> coefficients can be used to estimate the monthly
> heat flux through
> the slab.
>
>
> > Distance from edge of slab to domain edge?
>
> This value is what is used to set up the grid for
> the
> multidimensional calculation.  It should be far
> enough from the slab
> to be in an undisturbed ground temperature.   15
> meters is quite
> reasonable.
>
>
>
>
>
>
> On 4 Oct 2002, at 13:32,
> alexander.beisteiner@fh-pinka wrote:
>
> > Dear Sir/Madam
> > Using the programme Slab for calculating the
> ground temperature I
> > would need some help creating the IDF. Some fields
> in the various
> > objects are unclear to me:
> >
> > Surface Albedo: NO Snow/Snow?
> >
> > Under slab insulation: What does such a insulation
> look like as the
> > next field in the object depicts the width of
> strip of insulation.
> >
> > The area to perimeter ratio for this slab: this
> term is
> > self-explaining, but in the example idf-File
> (Slab2x2VertInsMplsAP10)
> > this ratio is 10- the specified dimension of this
> slab is 12x12.
> >
> > Thickness of slab on grade?
> >
> > Distance from edge of slab to domain edge?
> >
> > I am looking forward to your help.
> > Kind Regards
> >
> >
> > ----------------------------------------------
> > Alexander Beisteiner
> > Forschungs- und Technologietransfer
> > Pinkafeld GmbH
> > Steinamangerstrasse 21
> > 7423 Pinkafeld
> >
> > Tel.: 0043/3357/45370-1324
> > alexander.beisteiner@xxxxxxxxxxxxxxxxxx
> > http://www.fh-pinkafeld.ac.at
> >
>
>
>
>
========================================================
> EnergyPlus Testing and Support
> EnergyPlus-Support@xxxxxxxx
>
>

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