[TRNSYS-users] Cooling demand - QCOOL

[David BRADLEY]

Miriam,

  In addition to the things that Toni mentioned, also check to make sure 
that you did not leave the ground boundary temperature set to its 
default constant value of 0C. Leaving it set to the default provides 
rather a lot of free cooling to a building.

kind regards,

  David


On 05/26/2021 06:03, miriam di matteo via TRNSYS-users wrote:
>
> Dear all,
>
> I have some questions about the cooling energy demand and the output 
> "QCOOL" NType 31 and 33. I'm studying a residential building, and i 
> need to know its Cooling demand. My problem is that the QCOOL value is 
> very low. It is about 30kW, but the manually estimated value is more 
> than double (>60kW). I don't understand if I did something wrong in 
> the modelling or "QCOOL" isn't the Output that i need.
>
> I followed this steps to realized TRNSYS model :
>
>   * I did a geometrical model with TRNSYS 3D (Google SketchUp plugin),
>     with its 13 apartments and whit the internal walls, windows and
>     external shading devices (as walls, balconies etc...).
>   * In TRNBuild i characterized Wall and Windows levers, and insert
>     the Infiltrations and internal gain from people and light.
>   * I know the characteristic of the boiler and radiators installed;
>     The GAS bill about 2018 and 2019; Moreover I measured the trend of
>     temperatures inside an apartment for 4 days. I calibrated my
>     TRNSYS model with this data.
>   * So I inserted in my Thermal zones a ideal Cooling: Temperature set
>     point 26°C, unlimited, humidity off.
>
> I followed a similar way for Heating demand, I used an Ideal Heating 
> with a set point temperature of 20°C, unlimited, radiation part 20% 
> and without humidification. I didn't observed any problem with Heating 
> simulations.
>
> Can you confirm me that "QCOOL" (NType 31 and 33) represent my cooling 
> energy demand? In this case, if my TRNSYS model is correct the Value 
> of QCOOL it is necessary correct, right? It means that I have to look 
> for the error in the Trnsys model, is it true? Honesty i have no idea 
> where the error might be, It seems to me that everything is correct. 
> But it is the first time that i use Trnsys, so is easy that i insert a 
> wrong parameters or forget something, i think. Anyone have any advice 
> about it?
>
> I hope someone can help me, it is very important. Thank all in advance
>
> Miriam
>
>
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA

P:+1.608.274.2577
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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