[TRNSYS-users] cold bridge

[Karol Bandurski]

Dear Marion,

 

so cold bridge module is not useful in this case – am I right?

 

Regards,

Karol  

 

From: Marion Hiller [mailto:hiller at transsolar.com] 
Sent: Friday, July 13, 2012 10:13 AM
To: karol.bandurski
Cc: trnsys-users
Subject: AW: RE: [TRNSYS-users] cold bridge

 

Dear Karol, 

 

1) You recommend to set resistance of whole wall (include cold bridge) in “cold bridge window” (hmK/kJ) or resistance of “massless wall” (hm^2K/kJ). It doesn't matter which way will be chosen, dimension of element will be the same and only units will change m<->m^2. 

 

No, you need the thermal mass. The adjustment really depend on your wall construction. 

It is more adjusting the u-value of layer (if poassible) and thereby of a wall. 

For a wall with insulation I would increase the u-value for the insulation such that it includes the loss of the cold bridge. 

 

Best regards, 

 

Marion 

 

Dipl.-Ing. Marion Hiller 
TRANSSOLAR: KlimaEngineering - Technologien für energieeffizientes Bauen und Nutzerkomfort in Gebäude 
Munich - New York - Stuttgart + 49.711.67976.0 

Transsolar Energietechnik GmbH, Curiestrasse 2, 70563 Stuttgart 
Amtsgericht Stuttgart - HRB 23347, Steuernummer 99073/00911, USt-IdNr.: DE152272639 

Geschäftsführer: Dipl.Ing. Matthias Schuler, Dipl.Ing. Thomas Auer, Dipl.Phys. Stefan Holst, Prof. Dipl.-Ing. Bleicher  

  

 

  _____  

   

Von: Karol Bandurski [mailto:karol.bandurski at put.poznan.pl] 
Gesendet: Freitag, 13. Juli 2012 10:06
An: Marion Hiller
Cc: 'trnsys-users'
Betreff: RE: [TRNSYS-users] cold bridge 

 

Dear Marion, 

 

Thank you very much for your explanation! 

 

If I understand: 

 

1) You recommend to set resistance of whole wall (include cold bridge) in “cold bridge window” (hmK/kJ) or resistance of “massless wall” (hm^2K/kJ). It doesn't matter which way will be chosen, dimension of element will be the same and only units will change m<->m^2. 

 

2) In both case element will be massless. So what can I do to account mass and heat capacity of wall and cold bridge? 

 

Regards, 

Karol 

 

 

-----Original Message-----
From: Marion Hiller [mailto:hiller at transsolar.com] 
Sent: Friday, July 13, 2012 9:03 AM
To: karol.bandurski
Cc: trnsys-users
Subject: AW: [TRNSYS-users] cold bridge 

 

Dear Karol, 

 

If you define a "cold bridge" in TRNbuild the following happens: 

 

- Instead of defining layers as for a wall you define a "thermal resistance" 

(without mass effects) 

 

- Instead of setting an area as for a wall you define a lenght 

 

However, in the end this cold bridge is treated as "a massless wall". 

 

 

If you use a detailed radiation mode, you can't add surfaces (and a cold bridge would be surface somehow) in order to keep the geometry consistent. 

 

It is not recommended to draw very small surfaces in T3d to represent the cold bridge unless you need the inside surface temperature because very small surfaces may cause trouble for matrix generation. 

 

Therefore, the recommendation is to integrate the losses of a cold bridge into the wall by adjusting the u-value of a wall as previously mentioned by Adrien. 

 

I hope this helps. 

 

Best regards, 

 

Marion 

 

 

Dipl.-Ing. Marion Hiller 

TRANSSOLAR: KlimaEngineering - Technologien für energieeffizientes Bauen und Nutzerkomfort in Gebäude Munich - New York - Stuttgart + 49.711.67976.0 

 

Transsolar Energietechnik GmbH, Curiestrasse 2, 70563 Stuttgart Amtsgericht Stuttgart - HRB 23347, Steuernummer 99073/00911, USt-IdNr.: 

DE152272639 

Geschäftsführer: Dipl.Ing. Matthias Schuler, Dipl.Ing. Thomas Auer, Dipl.Phys. Stefan Holst, Prof. Dipl.-Ing. Bleicher 

 

 

 

-----Ursprüngliche Nachricht----- 

Von: Karol Bandurski  <mailto:%5bmailto:karol.bandurski at put.poznan.pl%5d> [mailto:karol.bandurski at put.poznan.pl] 

Gesendet: Donnerstag, 12. Juli 2012 18:25 

An:  <mailto:trnsys-users at cae.wisc.edu> trnsys-users at cae.wisc.edu 

Betreff: [TRNSYS-users] cold bridge 

 

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