Hello,
Thank you for your answer.
As I wrote, there is only one wall of 1m² and with a coefficient of 1W/m²K and the coldbridge.
The boundary condition for the wall is 20°C and the inside temperature is 19°C.
The coldbridge is linked to a orientation with no radiation and a outdoor temperature and tsky of 20°C.
The static loss output (QUA) well gives me 2 W but for me the QSENS output doesn’t give me that but a result of 6 W. How can you explain that?
As I wrote before it seems to have a factor of 5 when I change resistance values or lengths of coldbridge.
Moreover, if I change the coldbridge as a wall with also a orientation with no radiation and a fixed outdoor temperature, I have also approximately the same factor between the result I expect and what I have for QSENS output.
Thank you in advance if you have an idea.
Best regards,
Pauline GELIN
Ingénieur Conception environnementale
10 avenue des canuts
69120 VAULX EN VELIN
T : 04.37.45.33.33
Ligne directe : 04.37.45.33.47
De : trnsys-users-bounces@cae.wisc.edu [mailto:trnsys-users-bounces@cae.wisc.edu] De la part de Avesani Stefano
Envoyé : lundi 30 septembre 2013 11:20
À : TRNSYS users mailing list at the Solar Energy Lab, UW-Madison; David BRADLEY
Objet : Re: [TRNSYS-users] us of Coldbridges
Hi Pauline,
We are deeping the issue of thermal bridges in TRNSYS trying to find the best way of simulating this. What I am trying to simulate is a very simple zone with just one thermal bridge as transmitting external surface. Actually the QSENS calculated is coherent with the whole zone energy balance (of which the CBR “surface” is just one component and the other surfaces contribute to the energy balance even if they are set with BC identical). The heat flux lost through the CBR is then coherent with the formula q[W] = psi*l*deltaT.
What kind of zone have you used? Other surfaces? Which BC?
Looking forward to finding a good answer!
kind regards
Stefano
EURAC research
Institute for Renewable Energy
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t +39 0471 055 654
f +39 0471 055 699
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From: trnsys-users-bounces@cae.wisc.edu [mailto:trnsys-users-bounces@cae.wisc.edu] On Behalf Of Pauline GELIN
Sent: Thursday, 19 September, 2013 13:35
To: David BRADLEY; trnsys-users (trnsys-users@cae.wisc.edu)
Subject: [TRNSYS-users] us of Coldbridges
Hi,
Sorry to multiply the questions but I I try to consolidate our simulations of buildings and another question remains about how the values of resistance and length for a coldbridge are used.
When I want to simulate a very simple building zone (one wall of 1m² with a U equals to 1W/m²K and one coldbridge of 1m with a U equals to 1W/mK) , with no weather data, a constant outside temperature of 19° and a constant inside temperature of 20°C, the QUA output (meaning static losses transmission) is well given as 2 W but the QSENS outputs isn’t (it seems to be equal to 6 W).
When I change lengths or resistance values, it always seems to have a factor of 5 between the input value of coldbridge and the output value of QSENS.
Could someone explain this to me?
Thank you very much for your help.
Best regards,
Pauline GELIN
Ingénieur Conception environnementale
10 avenue des canuts
69120 VAULX EN VELIN
T : 04.37.45.33.33
Ligne directe : 04.37.45.33.47