[TRNSYS-users] Re : RE: Wall definition

[Julie Lestrade]

Hello Mariëlle 

Thank you for your quick answer.

1) For this question  I do understand this in principle but I don't see how/when TRNSYS is considering it. By the way, what about the capacitance ? is the default value calculated by TRNSYS a good one ? 

2) I understood I could do that, but it's calculated by default and I don't particularly know the solar absorbance of the material. So I was wondering if the calculation was alright ?

3) Thank you for that one : really helpful ! 

4) Anyone ? 

5) Yes I'm adding a question here : for the ground definition, it is important to set the temperature of the earth below. By default it's 15°C. Does anybody know for which region of the world this is true ? 

Thank you again.

Julie


Julie LESTRADE
Ingénieur d'études

CEDRE
Ophira 1, 1 Place Bermond
06560 SOPHIA-ANTIPOLIS
Tel : 04 92 96 03 77
Port : 06 45 68 07 53




Message original Re : RE: [TRNSYS-users] Wall definitionDe : Mariëlle Nuchelmans <M.Nuchelmans at chri.nl>
A : Julie Lestrade <lestrade.julie at cedre-sophia.com>, "trnsys-users at cae.wisc.edu" <trnsys-users at cae.wisc.edu>
Date : 2010-07-12 13:03:15


 Hello Julie,   Some answers:   If there is thermal mass, it is important (heat accumulation). In your case, with isolation at the outside, you will have thermal mass. If you add a wall to a zone, the inside of the wall is in your zone, the outside not.   In your wall definition screen, there you can add the solar absorbance (characteristic of the material)   If goesurf is set to zero, the incoming solar radiation is distributed to all the walls in the zone. If you change geosurf (say 0,3 to one wall, and 0,7 to the others) Then the wall with geosurf 0,3 gets 30% of the incoming radiation.     Kind regards, 
   
 
 Mariëlle Nuchelmans   Van: Julie Lestrade [mailto:lestrade.julie at cedre-sophia.com] 
 Verzonden: maandag 12 juli 2010 13:53
 Aan: trnsys-users at cae.wisc.edu
 Onderwerp: [TRNSYS-users] Wall definition 
   Dear Trnsys users,
 
 I was wondering about some details in the wall definition. 
 
 1) Usually, the building I represent is insulated from the outside. When I choose the layer that compose my wall I have an order (inside toward outside). I was wondering if there was any importance in that ? Because it did not seem to me that trnsys took into account the thermal bridges ? am I wrong ? 
 
 2) how can we choose the solar absorbance of the wall ? is it calculated ? if yes how ? if not how is it determined ? how can we determine it ?
 
 3) I read somewhere here that the geosurf should be set to 0. am I right ? if yes why is that ? if not how do we choose the repartition ?
 
 4) What about the wall gain parameter ? I notice it is set to 0 by default and in my results, the solar gains are equal to zero if there is no windows. Is that because my wall gain is zero ? To my mind it's not really representative of the reality. Should I put a wall gain different from 0 ? if yes how do I choose ? 
 
 Thank you for your feedbacks ! 
 
 Julie Julie LESTRADE
 Ingénieur d'études
 
 CEDRE
 Ophira 1, 1 Place Bermond
 06560 SOPHIA-ANTIPOLIS
 Tel : 04 92 96 03 77
 Port : 06 45 68 07 53   
 
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