[TRNSYS-users] Temperature course and reaction time

Mon Oct 27 07:42:17 PDT 2014

David and Stuart,

thank you for the replies.

That was the solution to my problem.
But now there is a new question related to this topic:

How can I simulate a building for short times ?
I want to know the behaviour of a building so that I can program a controller for the building.
Is there a chance to simulate a building with a timebase from 1 minute ?
If I do so, then there will be problem with the CFT coefficients. 
Or can I still simulate with the step stairs and get a good results ?
Have someone experiences for short time simulations ?

Kind regards,

Masood Mobarak

--------------------------------------------
Dols, William Stuart <william.dols at nist.gov> schrieb am Mi, 22.10.2014:

 Betreff: Re: [TRNSYS-users] Temperature course and reaction time
 An: "TRNSYS users mailing list at OneBuilding. org" <trnsys-users at lists.onebuilding.org>
 Datum: Mittwoch, 22. Oktober, 2014 23:29 Uhr

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 Masood,

 Here are a couple of papers related to this topic.

 Delcroix, B., M. Kummert, A. Daoud, and M. Hiller. 2012.
 Conduction transfer functions in TRNSYS multizone building
 model: Current implementation, limitations and possible
 improvements. in Fifth National Conference of IBPSA-USA
 (SimBuild 2012). Madison, WI.

 Delcroix, B., M. Kummert, A. Daoud, and M. Hiller. 2013.
 Improved Conduction Transfer Function Coefficients
 Generation in TRNSYS Multizone Building Model, in 13th
 Conference of International Building Performance Simulation
 Association (BS2013): Chambery, France.

 - Stuart 

 From: TRNSYS-users
 [mailto:trnsys-users-bounces at lists.onebuilding.org]
 On Behalf Of David BRADLEY

 Sent: Wednesday, October 22, 2014 4:29 PM

 To: TRNSYS users mailing list at OneBuilding.org;
 masood.mobarak at yahoo.com

 Subject: Re: [TRNSYS-users] Temperature course and
 reaction time 

 Masood,

   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,

  David

 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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 --  
 *************************** 
 David BRADLEY 
 Principal 
 Thermal Energy Systems Specialists, LLC 
 22 North Carroll Street - suite 370 
 Madison, WI  53703 USA 

 P:+1.608.274.2577 
 F:+1.608.278.1475 
 d.bradley at tess-inc.com

 http://www.tess-inc.com

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