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[EnergyPlus_Support] Re: Question to Slab program

Hello Jean,
do you consider that heat flows from the internal environment towards the external air passing through the ground? That happens in particular along the perimeter. 
I know that the subject is dealt with by Annex D (Application to dynamic simulation programmes) of the European technical standard EN ISO 13370:2008 "Thermal performance of buildings - Heat transfer via the ground - Calculation methods", but I have never used it? 
Has someone got more experience?
Best Regards
Francesco Passerini


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Kruis, Neal" <neal.kruis@...> wrote:
>
> Jean,
> 
> The deep ground boundary condition is a user input. You may specify either a constant temperature or a zero heat flux condition. Best practice is to specify a constant temperature equal to the average annual air temperature at the depth of either the water table, or 30 meters...whichever is closer to the slab.
> 
> Regarding the slab thickness, the input SLABDEPTH shouldn't have any restriction. In fact, often times, depending on the material properties of the slab, the finite difference program will have to increase the thickness of the slab to ensure a computationally stable solution. I have seen some pretty thick slabs in the program much thicker than 25 inches.
> 
> Hope that helps.
> 
> Neal Kruis
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jean marais
> Sent: Friday, April 20, 2012 3:57 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Question to Slab program
> 
> 
> 
> Where does it take its deep ground temperatures from? the weather file?
>



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