Re: [TRNSYS-users] Type 64 and 67 shading mask

Dear David,

Thank you for your answer. I think that I am going to use type 67 only, following your advice.

However, I have a doubt about what you say in your answer :

“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.”

However, from the TRNSYS manual : “The surface angles for which angular obstruction heights are provided correspond to absolute azimuths; they are NOT specified relative to the azimuth of the opening”.

I understand from this that -180 corresponds always to North (for our Hemisphere), -90 to East , 0 to South and 90 to West, whatever the surface azimuth is. Thus, I can just past and copy the same profile for each opening, right? There should be no need to change the position on the horizon.

Thank you for your attention.

Best regards,

Marcello Caciolo
Responsable Outils et Méthodes d'Analyse Energétique

cid:image003.jpg@01CD4E08.954D04D0

Cellule Efficacité Energétique et Environnementale

INGÉNIERIE PROJETS
15 rue Nina Simone
CS 39601 - 44096 Nantes cedex 1
Tél.: +33 02 40 41 06 57
marcello.caciolo@cofelyaxima-gdfsuez.com

Le 26 mai 2015, nous emménageons au 15 rue Nina Simone – CS 39601 – 44096 Nantes cedex 1

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De : David BRADLEY [mailto:d.bradley@tess-inc.com]
Envoyé : jeudi 11 juin 2015 22:11
À : TRNSYS users mailing list at OneBuilding.org; Caciolo Marcello (Axima Concept)
Objet : Re: [TRNSYS-users] Type 64 and 67 shading mask

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@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

Cellule Efficacité Energétique et Environnementale

INGÉNIERIE PROJETS
15 rue Nina Simone
CS 39601 - 44096 Nantes cedex 1
Tél.: +33 02 40 41 06 57
marcello.caciolo@cofelyaxima-gdfsuez.com

Le 26 mai 2015, nous emménageons au 15 rue Nina Simone – CS 39601 – 44096 Nantes cedex 1

Nos numéros de téléphone restent inchangés
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