Julie, Knut,
Thanks a lot for the answers.
So the formula a thought, is correct.
Kind regards,
Joke De Beuckelaer
project engineer mep
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From: Julie Lestrade
[mailto:lestrade.julie@cedre-sophia.com]
Sent: donderdag 4 november 2010 10:28
To: Knut Erik Enerstvedt; Joke De Beuckelaer
Cc: trnsys-users@cae.wisc.edu
Subject: Re : Re: [TRNSYS-users] external shading factor (multizone
building)
I asked about
this before and I'm forwarding you the answer I got and was valid when i tested
the influence of my blinds on the heating/cooling energy necessary for the
building.
hope this is useful.
Best regards,
Message original Re : Re:
[TRNSYS-users] Blinds
De : Adrien
JEZEQUEL - ITF <a.jezequel@itf.biz>
A : trnsys-users@cae.wisc.edu
Date : 2010-06-22 15:44:27
Dear
Julie,
I suggest you to put an equation tool outside of Type56. In that equation tool,
ESHAD (the ratio of non transparent area
of the shading device to the whole glazing area, as defined in TRNBUILD) will be calculated
depending on blinds position.
If you consider that :
- GWINDOW
= solar shading factor of window only, which is constant (60% for example,
which means that 60% of solar radiation goes through the window)
- FS
= solar shading factor of your system Window + Shadings.
FS depends on blinds use, - if blinds are used, FS = 0.2 (for example)
- if not, FS = GWINDOW
In
that way, FS is calculated as the product between :
- the
amount of solar energy which pass through external shading device when
they're used => (1-ESHAD)
- ESHAD = 0 means no shading
- ESHAD = 1 means zero transmission
- and
window solar shading factor (GWINDOW)
- FS = GWINDOW.(1-ESHAD)
(1)
Regarding (1)
ESHAD = (1- FS/GWINDOW) (2)
No you have a relation
between ESHAD, FS and Window G-Value :
- When
blinds are up, solar radiation are only blocked by the window solar
shading factor => FS = GWINDOW and ESHAD = 0.
- When
blinds are down, solar radiation are blocked by window and external
shadings => FS = 0.2 (for the whole system in that example), ESHAD =
(1-0.2/0.6) = 0.667 that means that
66.67% non transparent area of the shading device to the whole glazing
area)
Regarding (1) FS = 0.5*(1-0.0.667) = 0.5*0.4 = 0.2 which is the total shading factor you want.
Best
|
Adrien JEZEQUEL |
||
|
ITF |
62, Rue du Bolliet |
|
|
Phone : |
+33(0) 479 750 029 |
|
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Message original Re : Re:
[TRNSYS-users] external shading factor (multizone building)
De : Knut Erik Enerstvedt <knut.erik.enerstvedt@gmail.com>
A : joke.d@vkgroup.be
Date : 2010-11-04 09:33:18
Joke,
I
think you should only consider the g-value of the shading device when
calculating external shading factor. The g-value
of
the window is handled separately. So if the g-value of your shading device is
0.23, the external shading
factor
becomes 1 - 0.23 = 0.77.
Someone
please correct me if I am wrong.
Kind
regards,
Knut
Erik Enerstvedt
>Dear trnsys-users,
>I’ve a question about how to calculate
the external shading factor (multizone building). Is the following correct?
>Suppose I’ve a window with a g-value of
0,37 and a g-value of 0,23 (external shading device + window).
>The external shading factor becomes
then: 1 – (gwindow+shadingdevice/ gwindow) = 1- (0.23/0.37) = 0.38
>Kind regards,
>Joke De Beuckelaer
>project engineer mep