Re: [EnergyPlus_Support] More on Core/Perimeter Temperatures

["Michael J. Witte" <mjwitte@xxxxxxxx>]

> 2. Is there any way to consider a slab whose area is fully insulated?
> 
> 3. How can I consider a slab made up o several material layers?

The EnergyPlus slab preprocessor only allows one material layer for the slab.  
To model a fully insulated slab would required entering average thermal 
properties for the actual slab+insulation as the slab properties.  This might 
not be a bad approximation, but it has some serious limitations.

Mike


On 21 Apr 2006 at 8:25, Jeff Haberl wrote:

> Insulation is normally used around the perimeter because that is where the
> largest Delta-T is experienced by the slab. A detailed analysis is complex,
> involving soil properties, weather conditions, zone temps, surrounding
> structures, and 2 or 3 dimensional heat transfer. There have been many studies
> on this, two recent studies of note include the work by Moncef Krarti and Bill
> Bahnfleth, both are documented in the ASHRAE literature. LBNL has also
> published several simplified, yet accurate, reports on this as well by Joe
> Huang and Fred Winklemann. 
> 
> We've watched soil temps under a habitat house for 5 years, and are still
> learning more each time we look at the data. The center sensor follows the
> thermostat, the sensor under the south side is influenced by solar radiation
> on the exposed slab, the sensor on the north side behaves more like expected,
> following the OA temp with a lag of 2 to 3 weeks. 
> 
> Jeff
> BB 8=!  8=)  :=)  8=)  ;=)  8=)  8=(  8=)  :=')  8=)  8=)  8=? BB
> 
> Jeff S. Haberl, Ph.D., P.E.............................jhaberl@xxxxxxxxxxxx
> 
> Professor......................................................Office Ph:
> 979-845-6507
> 
> Department of Architecture.......................Lab Ph: 979-845-6065 
> 
> Energy Systems Laboratory.......................FAX: 979-862-2457 
> 
> Texas A&M University..............................77843-3581
> 
> College Station, Texas, USA.......................URL: www-esl.tamu.edu
> 
> BB 8=/  8=)  :=)  8=)  ;=)  8=)  8=()  8=) 8=?  8=)  8=)  8= BB
>  
> 
> -----Original Message-----
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Sent: Thu Apr 20 17:42:31 2006
> Subject: [EnergyPlus_Support] More on Core/Perimeter Temperatures
> 
> Hi,
> 
> 1. Could anyone explain to me why the physical model employed by the 
> slab calculation has insulation under the perimeter region, but not 
> under its core region? (At least this is what looks like from the 
> figure that comes along the guide).
> 
> 2. Is there any way to consider a slab whose area is fully insulated?
> 
> 3. How can I consider a slab made up o several material layers?
> 
> Thanks a lot for your help,
> jose
> 
> 
> 
> 
> 
> 
> 
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>  
> Yahoo! Groups Links
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> 
> 
>  
> 
> 
> 
> 
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
> Attachments are not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
> 
> EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf and press the
> "search" button.
>  
> Yahoo! Groups Links
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> 
>  
> 
> 
> 
> 
> 


========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx





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