[TRNSYS-users] TRNBUILD thermal bridge

[David Bradley]

Mattieu,
  I think that the wall type manager is where the incorrect units are 
displayed. My understanding is that a coldbridge does not have any 
thickness but it does have a length. For example, if you want to make a 
coldbridge to represent the lack of insulation where two exterior walls 
are joined, you would define a coldbridge that has the length of the 
joint. The resistance you enter should be in kJ/h.m.K (where the length 
is the length of the bridge). The error in TRNBuild is that the wall 
type manager should change the units of u-value when a coldbridge wall 
is displayed. Note that since the u-value displayed in the wall type 
manager is not actually used in calculation, that this error should not 
affect your results.
Kind regards,
 David


matthieu duclos wrote:
> Dear Trnsys Users,
>
> I have a problem about a bug for thermal bridge, I find an answer in 
> the archives but ...:
>
>
> Hi Nicola,
>
> nicola wrote:
> > Dear all,
> > I'm modelling a wall wit a thermal bridge effect.
> > I found a bug in TRNBuilt :
> > 1. If I put the value of resistence equal to xxx (hmK/kJ) in the layer
> > manager, the program create a wall with a U-value expressed in kJ/h
> > m^2K and a resistence equal to xxx in hm^2k/kJ!!!
> Thanks for finding this bug. I think it is only a problem of displaying
> the units. The resistance should be entered in h m^2K /kJ, and not h m
> K /kJ. When you check on the 'Layer type manager', the resistance is
> shown in h m^2K /kJ.
> > 2. the u-value of a wall with thermal bridge effect is lower than the
> > same wall without thermal bridge effect.
> The u-value displayed in the 'Wall type manager' is calculated by adding
> two reference heat transfer coefficients to the wall (7.7 and 25 W/m^2 
> K).
>
> Best regards,
>
> Diego
>
>
> ... in "Walls" when I choose a coldbridge I can put the value for 
> length in m , not a surface in m^2.
>
> What is the solution?
> If the solution is all in m^2, how can I change a linear thermal 
> bridge to surface thermal bridge?
>
> Thanks in advance,
>
> Matt
>
>
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Thermal Energy System Specialists (TESS), LLC 
David BRADLEY                      22 N. Carroll Street - Suite 370 
Partner                            Madison, WI 53703 
                                   USA
P: +1.608.274.2577 
F: +1.608.278.1475
E-mail: bradley at tess-inc.com 
Web Pages:  http://www.tess-inc.com    and      http://www.trnsys.com

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