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Ground temperature warning in the simulation of EnergyPlus

asked 2015-12-02 02:26:49 -0500

tech91's avatar

updated 2015-12-02 07:49:22 -0500

How can I solve this problem in EnergyPlus when I do the simulation?

Program Version,EnergyPlus, Version 8.4.0-832e4bb9cb, YMD=2015.12.02 09:25,IDD_Version 8.4.0
   ** Warning ** GetHTSurfaceData: Surfaces with interface to Ground found but no "Ground Temperatures" were input.
   **   ~~~   ** Found first in surface=A84D86
   **   ~~~   ** Defaults, constant throughout the year of (18.0) will be used.
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answered 2015-12-02 03:08:25 -0500

The warning is pretty clear: you have surfaces in contact with ground, but you haven't specified ground temperatures in your model.

If you don't want to see this warning, you need to put some ground temperatures. Check out the Input/Output reference, starting at Site:GroundTemperature:BuildingSurface.

As stated:

Caution: The “undisturbed” ground temperatures calculated by the weather converter should not be used in building losses but are appropriate to be used in the Site:GroundTemperature:Shallow and Site:GroundTemperature:Deep objects. The reasoning (for building losses) is that these values are too extreme for the soil under a conditioned building. For best results, use the Slab or Basement program described in this document to calculate custom monthly average ground temperatures (see the Ground Heat Transfer section). This is especially important for residential applications and very small buildings. If one of these ground temperature preprocessors is not used, for typical commercial buildings in the USA, a reasonable default value is 2C less than the average indoor space temperature.

Documentation on how to use the Detailed Ground Heat transfer with the preprocessors Slab or Basement is here.

There's also the option of using @Neal Kruis's Kiva

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Thanks for the support. Could you explain better temperatures assigned to the ground of a office building (thermal zone)? Amsterdam location. There is a table of the average monthly temperatures?

Thank you so much

tech91's avatar tech91  ( 2015-12-02 03:35:28 -0500 )edit

If you want to have accurate temperature, you need to use a preprocessor (slab, basement, or kiva) and calculate them based on your actual constructions in contact with the ground and the weather file for your location. If you want to know how to do that, post another question and I'm sure some experts will help you (I'm definitely not one of them).

Otherwise, as stated in the I/O reference guide bit that I posted above, you can put 2C below your indoor temperature.

Julien Marrec's avatar Julien Marrec  ( 2015-12-02 06:50:37 -0500 )edit
1

More info here

Jamie Bull's avatar Jamie Bull  ( 2015-12-02 07:54:32 -0500 )edit

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Asked: 2015-12-02 02:26:49 -0500

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Last updated: Dec 02 '15