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RE: [EnergyPlus_Support] Re: Ground Temperature: Building Surface

What could be a probable default ground temperature for Indian climates, say New Delhi or Jaipur?
It does not matter where you are, the deep earth temperature is maintained by the ice at the poles and the sea water current.  It will be in the range between 18 to 22°C.  If you go deeper, the earth  temperature would increase. 
The surface ground temperature below the building is a value between this deep ground and the undisturned surface grouond temperature, which varies with the daily outdoor air temperature and the solar radiation on the surface. 
If you have a small building with no shade outside, the ground surface temperature under the building will follow the surface ground temperature not covered by the building via horizontal conduction.  The slab and basement program will help you to make this calculation.
When the building is air-conditioned to say 27°C, you assume 27 - 2 = 25 as the temperature below the building.  This is reasonable. 
For an un-conditioned ground floor zone in the middle of a building, the ground cools the zone in Summer and heats the zone in Winter.
To keep the basement temperature above zero in Winter, the basement wall  need to be insulated to a depth of  1 meter below the ground surface and part of the ceiling up to one meter from the external wall. (The frost line)
New Delhi is not near the sea, so you may need a higher value.  The general guide is two degree less than the monthly average of the daily available.  Without looking at the .stat file, my guess is 22 to 24 degree as the suitable under building ground temperature for your location.. 
I am using 25°C for Singapore.    20 to 22 degree C (Monthly average) for Toronto, Canada.
What you need to do is to measure a few basement floor temperature at night (3 to 5 am) to confirm that the number chosen is reasonable.
If you are doing detailed daily experiment on the building, you would need the exact value, and some observation on the soil moisture condition (diffusivity).  For the annual energy usage calculation, a monthly average value is good enough.
Dr. Li


To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jippnojunk@xxxxxxxxx
Date: Sat, 12 Feb 2011 20:39:03 +0000
Subject: [EnergyPlus_Support] Re: Ground Temperature: Building Surface

Why don't you just use the technique described in the documentation?

OK. I have reread the section in I/O manual.
The GroundHeatTransfer:Control object determines if the Slab and Basement preprocessors are going to be executed. When a Slab or Basement run is performed the results are saved in files with extensions .SLAB or .BSMT so that they do not need to be rerun if no input changes are made to the GroundHeatTransfer:Slab or GroundHeatTransfer:Basement objects."

I have never done it but here is my understanding.
add a GroundHeatTransfer:Control object to run the preprocessor. It will calculate the ground temperatures to use from the climate file you spécified. Get the results in the .SLAB or .BSMT file and enter those results in the relevent ground temp objects.

Let me know it that does it.
I am learning as well.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Tony David <tony.energie@...> wrote:
> Hi everyone
> �
> The Energy plus documentation specifies that for typical commercial buildings in the USA, a reasonable default value for ground temperature: building surface�is 2C less than the average indoor space temperature.
> What could be a probable default ground temperature�for Indian climates, say New Delhi or Jaipur?
> �
> Thanks
> Tony
> �
> �


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