Re: [TRNSYS-users] Initializing wall temperature

[David BRADLEY <d.bradley@tess-inc.com>]

Marcello,
  To my knowledge there is not a way to precondition the walls. I would expect that with such thick walls you would need to run the building for at least a 6 month period (if not a 1 year period) in order to get rid of all the initial value transients. If it makes you feel any better to know that you are not alone in your misery of waiting for a slow simulation, I often have models that run more slowly than 1 month per 40 minutes! Some ground coupling simulations run at near real-time!
kind regards,
 David

On 10/05/2015 08:06, marcello.caciolo@cofelyaxima-gdfsuez.com wrote:

Dear Trnsys users,

 

I am currently working on a very massive building, with many zones and very with high thermal inertia (concrete wall from 60 to 120 cm of thickness). The model takes 40 minutes to calculate 1 month.

 

I observe than after one month, final temperatures in zones are still very depending on initial temperatures. For this reason, I tried to adjust initial temperature to be nearer to expected final temperatures (in the order of 35-40°C).

 

However, in the first part of the simulation, temperatures drop quickly to 25-30°C, depending on the zone. This is quite surprising, considering that there are no heat losses and there are heat gains. The only explication I found is that surface temperatures are not initialized to initial temperature of the zone, and thermal mass takes time to warm up.

 

Do you know if there is a way to force surface temperatures to zone temperatures at the beginning of a simulation ?

 

Thank you !

 

Best regards,                      

Marcello Caciolo
Responsable Outils et Méthodes d'Analyse Energétique

Service Engagement Energétique - Direction Ingénierie Conception
15 rue Nina Simone
CS 39601 - 44096 Nantes Cedex 1
Tél.: +33 02 40 41 06 57
marcello.caciolo@cofelyaxima-gdfsuez.com

P Pensez à l'environnement avant d'imprimer ce message

 

_______________________________________________
TRNSYS-users mailing list
TRNSYS-users@lists.onebuilding.org
http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org

-- 
***************************
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@tess-inc.com

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