Pauline Gelin,
the resulting u-value is dependent on the boundary conditions. Type 56 take the current boundary conditions
(actual temperatures etc.)
whereas WINDOW takes fixed conditions according to the selected standard. This means in order to have the same
values you need
to have the same boundary conditions.
The u-values displayed in the window type manager are read from the footer lines which are added to the WINDOW
report file.
If you create a new glazing you have to add these values manually.
Without looking at your project it is impossible to give further advice. B4_QT is a zone output for all surfaces
of a zone.
I have no clear view on how you use this output for calculating the u-value of a window.
However, the following explains the calculation principles of Type 56 a little.
Type56 – glazing modeling
In the window type manager you can select 5 options for calculating the spacer:
If you select ID-Spacer = 0 it uses the data from the WINDOW report (this includes the height and width of
the glazing).
Otherwise, it uses the selected space condition of no spacer.
Type 56 divides the glazing area into glazing and edge area. The “edge area” is defined as
63.5mm wide band at glass periphery. The region inside this is what is called
"center of glass".
The height and width of the glazing defined the window type manager and the WINDOW report file, respectively.
Type 56 calculates the area weighted conduction values for the total glazing based on temperature dependent
u-values for edge and center of glass under the current conditions.
Type 56 - FRAME modeling
TRNSYS doesn’t use the frame data from the WINDOW report file.
In principle there are two ways of simulating the frame:
1.)
Define the frame as a wall
This is the precise way to do it because the frame has it’s own surface temperature (independent from the window)
in the solving processing in Type 56. However, it is more effort to define it.
Define frame properties like frame fraction, solar absorption, emissivity, conduction
(1/Rcond) in window type
Type 56 calculates a temperature depending resulting for the glazing (including edge effect and shading)
and then applies a simple area weighting to the conduction:
Best regards,
Marion
Dipl.-Ing.
Marion Hiller
Transsolar Energietechnik GmbH
Curiestraße 2
70563
Stuttgart
Telefon: +49 711 67976-0
http://www.trnsys.de
Transsolar: KlimaEngineering- Technologien für energieeffizientes Bauen und Nutzerkomfort in Gebäuden
Stuttgart
– München – New York – Paris
Geschäftsführer :Diplom-Ingenieur
Matthias Schuler, Diplom-Ingenieur
Thomas Auer, Diplom-Physiker Stefan Holst, Diplom-Betriebswirt
Dieter Schnelle
Eingetragen beim Amtsgericht
Stuttgart HRB 23347,
Steuernummer: 99073/00911,USt-IdNr.: DE 152272639
Hi,
When I use a glass
that I had created from
WINDOW6 software, it turned out
that the Uwindow value, deduced from the B4_QT output doesn’t
correspond to what I expected, when I calculated it with
the Ug value
shown in the database TRNBUILD, the percentage frame and Uframe filled in
TRNBUILD.
After many tests, it appears that the Uwindow calculated differs if I take a glazing created in WINDOW6
(for which I didn’t give any information of spacer in order to change this in the TRNBUILD project) or
a
glazing initially given in the TRNBUILD database.
While
Uframe percentage and spacer values indicated in my database windows are the same.
Does anyone know where
does
this difference come from?
What values of Uframe,
and percentage
frame and
spacer, does
TRNBUILD consider
:
those entries in the database glazings or those filled in the database window that is created for each project?
Then, also with a test of 100% glazing window, if I use a glass type I created with WINDOW 6 without frame and spacer (because I want
to choose after the spacer and the frame in TRNBUILD), which is shown in WINID with a indicative Ug of 1.07 W/m²K, correct value for this type, when I look the outputs Uwin and B4_QT, these ones give me a Uglass of only 0.57 W/m²K !
Could you explain to me what I did wrong? And more especially, how TRNSYS could calculate this value?
Thanks a lot in advance for all your answers.
Best regards,