[TRNSYS-users] Internal glazing specification

[jeannieboef]

I believe that the calculation are according to European Norms.  
Something like DIN EN 674 (CEN) and  416.

Sent from my iPhone

On 02.07.2012, at 17:20, "Antoine Gautier"  
<antoine.gautier at solamen.fr> wrote:

> Dear users
>
>
>
> I am really puzzled by Werner’s post hereunder.
>
> http://sel.me.wisc.edu/trnsys/mailinglist/archive2003/msg00297.html
>
>
>
> If I understand it well, characteristics for internal glazing  
> systems should be specified regarding external glazing systems  
> characteristics. For instance internal transmittance should be  
> different than normalized value if spectrally selective transmission  
> is performed by external glazing systems. The reason invoked being  
> that the same wavelength cannot be absorbed twice.
>
> However when I think about it,  I rather understand transmission  
> coefficient (thermal or visible) as a probability of transmission  
> averaged on a wavelength interval. Therefore I would intuitively  
> conclude that each glazing system transmits radiation as expected  
> regarding its normalized characteristics.
>
> When I simulate a fictive 2 * double glazing system in WINDOW with a  
> very wide middle air gap I get the following results.
>
>                                                            SHGC     
> Tvis
>
> Initial double glazing                             0.54      0.78
>
> 2*double glazing simulated                    0.41      0.62
>
> Characteristics of initial glazing**2         0.29      0.61
>
>
>
> So Tvis resulting from WINDOW calculation is close to the square of  
> initial Tvis value but SHGC is in-between.
>
> I would need help to conclude. How should internal glazing systems  
> be specified in Trnbuild?
>
>
>
> Also if Radiance users are amongst you I would be very interested to  
> know how they handle this issue when specifying transmissivity  
> values for internal glass materials.
>
>
> Best regards
>
> --
>
> Antoine Gautier
> Solamen SAS
> +33 6 58 24 02 60
>
> antoine.gautier at solamen.fr
>
>
>
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> TRNSYS-users at cae.wisc.edu
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