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[EnergyPlus_Support] Re: Ground temperature of Singapore

Heat transfer across a surface like the slab is related to the temperatures above and below. For indoors that are conditioned to a certain temperature, the ground temperature at the bottom surface is then changed significantly. The Slab preprocessor needs an assumed temperature at the bottom surface, the ground temperature, to start with. That is why you may need to use it iteratively.

For indoors that are not conditioned, the ground temperature, can, for most purposes, be assumed to be the Undisturbed Ground Temperature given in the .stat file, though it is not perfectly true to say that the ground temperature is not undisturbed. 

There are two sine waves. One for the daily and one for yearly temperature fluctuation. i have answered your question by email. If you like, i can email you my paper "EnergyPlus Building Simulation Program: Which Ground Temperature to use?" International Conference on Civil and Environmental Engineering for Sustainability. 3-5 April 2012, Johore Baru, Malaysia.


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "academicryan"  wrote:
> Update: *EnergyPlus developer please respond*
> OK I now know how to calculate soil temperature as a function of depth from Hillel, 1982.
> Essentially his equation says that at 0 m depth, monthly average soil temperature is the monthly average air temperature plus 1°C. This is basically a sine wave. With increasing depth, the soil temperature gets closer to the annual mean air temperature plus 1°C. 
> NEW QUESTION: Is this what 'Site:GroundTemperature:BuildingSurface' wants? i.e. 0 m depth soil temperature. Or some other depth? Or some other 'ground temperature' altogether?
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "academicryan"  wrote:
> >
> > Can somebody please help me do a very simple task.
> > 
> > Calculate/find the monthly ground temperature for Singapore. To clarify, this is the input for the 'Site:GroundTemperature:BuildingSurface'.
> > 
> > ------
> > 
> > Extra info - I've already tried the Slab utility, it comes up with very unbelievable results. Calculating some months below 17°C when Singapore air temperatures never drops below 21°C.
> >


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