[TRNSYS-users] Type 64 and 67 shading mask

[David BRADLEY]

Marcello,
   I'm not sure how one might combine Types64 and 67. Despite the fact 
that I wrote Type64, I have never been convinced that it was a very 
useful model. It computes the impact of a faraway mask on radiation 
falling on a horizontal surface and was intended to be a "quick and 
dirty" model to get a basic idea of shading by applying one mask to all 
surfaces regardless of their orientation. If you want a correct 
estimation of shading by obstacles (whether they are far off or nearby) 
then you should really use Type67 in order to be correct in the 
estimation of how the horizon affects that surface. The disadvantage of 
Type67 of course is that you need to provide a mask for each surface. 
However, all the masks can be provided in a single file and if you have 
more than one orientation to worry about then you can just shift the 
horizon index for each different orientation of in the file. The angular 
heights of obstructions don't change; only their position on the horizon 
changes.
best,
  David


On 06/11/2015 02:25, marcello.caciolo at cofelyaxima-gdfsuez.com wrote:
>
> Dear Trnsys users,
>
> I have a question about the possibility to use type 64 and type 67 
> together.
>
> In my projects, I use to define a “geographical” horizon line, valid 
> for all orientations, by type 64, and to use type 67 for masks due to 
> near obstacles (trees, buildings, …) (different for each surface). 
> Self-shading from overhang and wingwall are taken into account by type 34.
>
> Then, I connect outputs of type 64 to  type 67 and outputs of type 67 
> to type 34.
>
> However, type 34 provide a parameter to say if radiation is provided 
> by type 64 or 67, in order to avoid to take into account twice the sky 
> view factor, but type 67 does not.
>
> I wonder if this can have an impact on results.
>
> Could you please give me your advice?
>
> Thank you!
>
> Best regards,
>
> *Marcello Caciolo*
> Responsable Outils et Méthodes d'Analyse Energétique
>
> cid:image003.jpg at 01CD4E08.954D04D0
> *
> *Cellule Efficacité Energétique et Environnementale
>
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> <mailto:prenom.nom at aximaseitha-gdfsuez.com>
>
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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