[TRNSYS-users] Blinds

[Adrien JEZEQUEL - ITF]

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,
          o if blinds are used, FS = 0.2 (for example)
          o 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)
          o ESHAD = 0 means no shading
          o ESHAD = 1 means zero transmission
    * and window solar shading factor (GWINDOW)
          o *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
------------------------------------------------------------------------
www.itf.biz <http://www.itf.biz>
www.itf.biz <http://www.itf.biz>

	Adrien JEZEQUEL
Simulations Thermiques Dynamiques
*ITF*
	62, Rue du Bolliet
73230 St Alban Leysse
FRANCE
Phone :
Fax :
Mail:
	+33(0) 479 750 029
+33(0) 479 852 122
a.jezequel at itf.biz

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Le 22/06/2010 14:04, Julie Lestrade a écrit :
> Dear TRNSYS users,
>
> I was wondering about blinds in front of windows and how to take them 
> into account.
> In my case, they external blinds. They're up at certain time and down 
> at other (depending on radiation on the wall, time of day, ...).
>
> Should I take account of them in Type 56 ? on the windows considered 
> with 'external shading factor'  (that would be convenient since i can 
> use a schedule) ? If yes, I would like to have a total solar factor 
> for the window of 0.2 when the blind is down. Does that mean I should 
> put a shading factor 0.8 ? or is it more complicated than that ?
>
> Thank you for your answers
>
> Julie
>
>
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