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Re: [TRNSYS-users] Thermal mass is not considered in Type 56 simulation!!

Dear Mehrdad,
Hope you are doing well.

The results you are getting make sense, you have quite a massive and insulated unit with no ventilation whatsoever.
- When you have massive components in your unit, the fluctuation of the indoor temperatures reduces a lot, and
- With no ventilation (especially no induced ventilation by night, to make the night purge ventilation effect), and
- With the insulation, you are reducing the heat exchange between the inside and outside.
Therefore, these results are normal.

I'm working with multi-story residential buildings, and in the beginning I had very massive buildings with a fixed ventilation of 0.5 m/s and I used to get such results, especially that I'm working with hot climates...

I noticed also that we're talking about a temperature range of 12-19 degC... Have you tried to check the results in the summer?

All the best,
Amr


On Thu, Jul 24, 2014 at 7:05 AM, Mehrdad Farshchi <mehrdadfarshchi@gmail.com> wrote:

Dear Jochen,

 

Thank you for your email. I have modelled and simulated a simple rectangular building (15m x10m) in Sydney with Trnsys 17 software. Then using the Trnsys library I have edited the building components in order to make a heavy weight building as follows:

 

Floor = BST_H_FLO                   (see the figure attached)

External Wall = BST_H_EXT   (see the figure attached)

Roof= BST_H_ROO                  (see the figure attached)

 

Although Infiltration, Ventilation, Heating, Cooling and Comfort regime are off, the observed thermal lag was very low (less than an hour). Even I changed the wall concrete thickness to 0.4m and the result for the air temperature (TAir_H_0.4) did not show any changes in terms of thermal lag (please have a look at the graph attached)

Tambient: ambient temperature ,

TAIR_H_0.1:  air temperature of air node with above mentioned building component and setting and

TAIR_H_0.4 : air temperature of air node with above mentioned building component and setting the wall concrete thickness to 0.4m.

 

I wonder if you could please let me know how to resolve this issue.

 

Kind Regards
Mehrdad





On Thu, Jul 17, 2014 at 6:40 PM, hotline <hotline@transsolar.com> wrote:

Dear Mehrdad,

 

TYPE 56 considers thermal masses. I can imagine that you’ve set a high ventilation rates.

If so, you might compare the surface temperatures or the operative temperature instead.

 

Best  

 

__________________________________________________________________________________________________

 

Jochen Lam

TRNSYS Software Team


Transsolar Energietechnik GmbH

Curiestraße 2

70563 Stuttgart

Fax:        +49 711 67976-11
Email:    jlam@transsolar.com

Web:      www.trnsys.de

 

Von: TRNSYS-users [mailto:trnsys-users-bounces@lists.onebuilding.org] Im Auftrag von Mehrdad Farshchimonfared
Gesendet: Mittwoch, 16. Juli 2014 06:12
An: trnsys-users@cae.wisc.edu
Betreff: [TRNSYS-users] Thermal mass is not considered in Type 56 simulation!!

 

Dear Trnsys users,

 

I have modelled a residential building with different building components (including different thermal masses) using Trnsys 3d, Type 56 . The simulation results show no thermal lag between hourly inside air temperature of each zone even if, the heavy materials are used. It is weird as it seems that Trnsys does not take into account the thermal mass of walls, floors and etc.

 

Have you come across with this problem previously?  

 

If  yes, I wonder if you could please let me know how to resolve this issue as soon as possible.

 

 

 

 

Kind Regards

Mehrdad


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--
Amr Alaaeldin Elesawy

PhD Student | Building Engineering
Department of Architecture, Built Environment and Construction Engineering (A.B.C.)
Politecnico di Milano, Italy
+39 327 056 0018