Re: [EnergyPlus_Support] More on Core/Perimeter Temperatures

["Jeff Haberl" <jeffhaberl@xxxxxxxxxxxxxx>]

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
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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

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-----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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