Re: [TRNSYS-users] Windows shading coefficients

[David Bradley <bradley@tess-inc.com>]

Dear Maurizio

> 1) I'm currently
> modelling in PREBID a residential building for which the montly Shading
> Coefficients on the windows have been calculated with the software
> ECOTECT. I insert the SC in the appropriate field ("external shading
> coefficient") as an input and set the "view factor" to 0,5
> (vertical surfaces). It's the exact way? My doubt is that the solar
> incident radiation is halved (view factor = 0,5) and then reduced of the
> SC...

It is correct, provided that the shading coefficient from Ecotect is the
opaque fraction of the window (i.e. 1 = completely shaded).
The view factor to the sky (FSky) is only used for longwave radiation so
it will not interfere with shading.

The one thing to bear in mind about PREBID's external and internal
shading coefficient is that the entered fraction effects both beam and
diffuse radiation equally. Thus if you enter a value of 0.5 for the
external shading factor, half of the incident diffuse radiation and half
of the incident beam radiation will enter the space. If you want to treat
beam and diffuse radiation separately, you can use one of the external
shading models (Type34, or Type68).

> 2) It's possible to
> use old TESS libraries with TRNSYS 16 or are they already comprised in
> the new version?

Because of the change in coding standards for components between version
15 and 16, the TESS Libraries v. 1.x are not directly useable with
TRNSYS v 16. We have, however, expanded the libraries and released
version 2.0, which are not only compatible with TRNSYS 16 but are also
backwards compatible with TRNSYS 15. If you are interested in upgrading,
you will be credited the full amount that you paid for your version 1.x
libraries toward the purchase of version 2.x libraries. If you do not
wish to upgrade then you can follow the steps laid out in the TRNSYS 16
documentation that show you how to modify a TRNSYS 15 Type to make it
accessible from TRNSYS 16. I will send along a second email containing a
document that lists the contents of the 12 version 2.0 libraries as well
as an order form that contains the pricing information. I would be happy
to answer any questions that you might have about them.

Kind regards,
  David

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Thermal Energy System Specialists (TESS), LLC
David BRADLEY                           2916 Marketplace Drive - Suite 104
Partner                                        Madison, WI 53719
Phone: (608) 274-2577 USA
Fax: (608) 278-1475
E-mail: bradley@tess-inc.com
Web Pages:  http://www.tess-inc.com     and      http://www.trnsys.com

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