[TRNSYS-users] thermal resistance of external shading device

[Marion Hiller]

Dear Antoine,

 

looking at the calculation, it the resistance is always active when the
shading is active.

Maybe you confused due to the influence of the frame?

The u-value of the frame is not influenced by the additional resistance
of the shading.

 

The NTYPE 50 UWIN is calculated of three different parts:

a)   Centre of glass

b)       Edge of glass (influenced by the spacer)

c)       Frame

 

The Uglas (centre of glass and edge of glass) without the inner and out
outer heat transfer is calculated by

 

      Redge=(1/alfain+(rshdin*shdin)+1/uedge

     .                   +(rshdout*shdout)+1/alfout)/fe

      Rcenter=(1/alfain+(rshdin*shdin)+1/ucentr

     .                   +(rshdout*shdout)+1/alfout)/fg

      Rges=Redge*Rcenter/(Redge+Rcenter)

      UGLAS=1/(Rges-1/alfain-1/alfout)

 

Then the frame is included:

          UGL(N)=UGLAS* (1.-FFRAM)+UFRAM*FFRAM ! total window u-value
without inner and outer heat transfer

 

Finally the NTYPE 50 is calculated by:

         CASE (50) ! u-value of window (glass+frame)with standard inner
and outer heat trasnfer coefficients

            IF (HO.GT.30.) RO=0.04

            IF (HO.LT.0.005) RO=0.0

            IF ((HO.LE.30.).AND.(HO.GE.0.005)) RO=0.13

            UGLK=1./(1./(UGL(NWI)/3.6)+0.13+RO)

          ENDIF

          OUT(IOUT)=UGLK*3.6

 

Best,

 

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: Antoine Gautier [mailto:antoine.gautier at solamen.fr] 
Gesendet: Montag, 31. Oktober 2011 18:36
An: trnsys-users at cae.wisc.edu
Betreff: [TRNSYS-users] thermal resistance of external shading device

 

Dear all

 

I use the surface output Uwin to assess the thermal impact of an
external shading device.

As you know the thermal properties entered for the shading devices are
effective only if a shading device is actually defined for the window in
the zone description.

I get the following results whereas I specified DeltaR = 0.06 m2.K.h/kJ
in input. Does anybody understand this better than I do? i.e. why does
the shading factor modify the thermal impact though the shading device
is only active during periods of time with zero irradiation? Why do I
not get the expected DeltaR in output but half the value?

 

Shading factor  - Uwin w/o shading - Uwin with shading [kJ/h.m2.K] -
DeltaR [m2.K.h/kJ]

1          - 4.93 - 4.22 - 0.034

0.75      - 4.93 - 4.36 - 0.027

 

Thanks for your help

--

Antoine Gautier
Solamen
+33 6 98 78 56 46

antoine.gautier at solamen.fr

 


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