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Re: [TRNSYS-users] Cooling demand - QCOOL

Hi Miriam, (if you speak italian please let me know ;))

Did you have a look to the SUMMARY balance that is automatically printed by trnsys? Are the values coincidents?

It is hard to say something without checking the model, but I can assume that the problem could be in the cooling itself, but it could be also in a wrong implementation of the boundary conditions. For example:

1.      Did you check the solar gains (are also included in the SUMMARY balance)? Are realistic?

2.      Did you check the internal gains? Are the outputs of internal gains equal to what did you expect?

 

Please send me in case the trnsys model and the bui file in order that I can help you in details.

 

Toni Calabrese, MSc.

Wissenschaftlicher Projektleiter

toni.calabrese@spf.ch | toni.calabrese@ost.ch

 

T +41 58 257 4827

 

SPF Institut für Solartechnik

OST – Ostschweizer Fachhochschule

Oberseestr. 10 | CH-8640 Rapperswil | Switzerland | www.spf.ch | www.ost.ch

 

OST – Ostschweizer Fachhochschule ist der Zusammenschluss aus FHS St.Gallen, HSR Rapperswil und NTB Buchs.

 

From: TRNSYS-users <trnsys-users-bounces@lists.onebuilding.org> On Behalf Of miriam di matteo via TRNSYS-users
Sent: Wednesday, May 26, 2021 1:03 PM
To: trnsys-users@lists.onebuilding.org
Cc: miriam di matteo <dimatteo.1585179@studenti.uniroma1.it>
Subject: [TRNSYS-users] Cooling demand - QCOOL

 

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