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Re: [EnergyPlus_Support] Re: Ground tempe rature of Singapore




If you don't enter the indoor temperature, you will likely have unrealistic results.

You have not given your problem to the helpdesk == this is a user=user forum.

Rule of thumb - make your ground temperature -2C from your indoor temperature. I believe this is stated in the aux programs document if you choose not to believe the calculations from the slab program.


On 2013-01-18 19:32, academicryan wrote:
Hi Linda I have read that section at least 4 time trying to
understand it. I still don't really understand it very well but I'm
pretty sure its simply telling me to use the Slab program in the
EnergyPlus Utilities.

I've mentioned that the Slab program gives unrealistic results. What
I particularly don't understand about the Slab is why there is an
input for monthly averaged indoor temperature. This means I need the
indoor temperature to calculate the ground temperature. But to
simulate the indoor temperature, I need the ground temperature. This
seems like an impossible chicken/egg scenario of which one comes
first. I've even read somewhere I'm supposed to start with an
arbitrary indoor temperature and keep doing this chicken/egg cycle
until both ground and indoor temperatures converge and stabilise. This
seems really silly and tedious but maybe that really is what I'm
supposed to do?


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Linda Lawrie  wrote:

Read the auxiliary programs document on Ground heat transfer with
EnergyPlus. Look at the EPW file ground temperatures as well (which are
not suggested for the Site:groundTemperatures values)

On 2013-01-18 18:49, 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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>





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