[TRNSYS-users] Temperature course and reaction time

David BRADLEY d.bradley at tess-inc.com
Wed Oct 22 13:28:35 PDT 2014

   The steps are probably caused by a large difference between your 
simulation time step and your building's timebase. A wall's response to 
a change in ambient conditions is characterized by equations that have a 
series of coefficients each of which can be thought of as a relative 
weighting factor for a particular ambient condition stepping backwards 
in time. For example, there are some coefficients that tell how 
important the temperature difference across the wall was one time base 
ago, two time bases ago, three time bases ago, etc. You can set the 
timebase in TRNBuild (open the "outputs" window) and it is best if the 
timebase matches your simulation time step.
   I am not sure what simulation time step you are using but please bear 
in mind that many of the models in TRNSYS are not appropriate when used 
with tiny time steps. I would not recommend using a time step less than 
about 1 minute.
Kind regards,

On 10/22/2014 10:40, Masood Mobarak wrote:
> Hi @ all,
> I am writing my master thesis about room simulation and I am new to TRNSYS.
> I have two question and i hope that you can help me:
> 1. Question: How comes that the temperature course of a room (type 56) has alsways jumps/steps.
> For Example: When the ambient temperature is very cold then the temperature in the room falls, but in many little steps (See attachment).
> Is this a fault from the simulation? If not can someone explain me why this course is correct ?
> 2. The temperature in the room falls immediatly after the ambient temperature falls. Is this also correct? I thought there have to be some time until the temperature from the room will react to the ambient temperature or to heating the room. When the heating power beginn the temperature begins to raise. I thought that there have to be some minutes until it will beginn to raise.
> Kind regards,
> Masood Mobarak
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Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

d.bradley at tess-inc.com


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