[TRNSYS-users] external shading factor (multizone building)

[Nikolai Artmann]

Dear Knut, dear Joke

 

A g-value is always defined for a shading device in combination with a
glazing. As the g-value includes the heat flow from the internal surface
(glazing) to the room, a definition of a g-value of a shading device
without a glazing does not make sense. 

 

In TRNSYS the shading device is modeled by the external shading factor,
which reduces the solar radiation on the window. The heat flow to the
room is reduced by the same factor. So in my opinion Joke's calculation
is correct: 

 

external shading factor  =  1 - (gwindow+shadingdevice / gwindow)

 

Best regards

 

Nikolai

 

 

 

Nikolai Artmann

3-Plan Haustechnik AG, Winterthur
Telefon  052 / 234 70 66
Telefax  052 / 234 70 60
e-Mail: nikolai.artmann at 3-plan.ch <mailto:nikolai.artmann at 3-plan.ch> 

 

________________________________

Von: Knut Erik Enerstvedt [mailto:knut.erik.enerstvedt at gmail.com] 
Gesendet: Donnerstag, 4. November 2010 09:33
An: joke.d at vkgroup.be
Cc: trnsys-users at cae.wisc.edu
Betreff: Re: [TRNSYS-users] external shading factor (multizone building)

 

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

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