Re: [TRNSYS-users] Glass shading overhang with dynamic reflection coating

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

Tom,
  The "incident receiver radiation" term includes both beam radiation and diffuse radiation. Shading devices often either occlude the beam radiation completely or not at all whereas the diffuse radiation is reduced (more or less) by the view factor between the receiver and the sky. In the case of a venetian blind, the beam radiation is reduced by the blind but may or may not be reduced by the same fraction as the diffuse radiation. In fact I think that is rather the point of a venetian blind: it blocks the beam radiation more than it blocks the diffuse but still allows some to come through depending on the angle of the blades.
Regards,
 David

On 4/19/2013 03:13, Tom B wrote:

Dear all,
 
When I took a look at the multizone building with an overhang as it is made by the wizard in the Simulation Studio, I noticed that it uses both the "Incident receiver radiation" and the "Beam radiation on receiver" as an input for the multizone building. I was wondering whether anyone can explain to me why it needs both the Incident receiver radiation, which already is all the radiation on the window if I'm not mistaking, and in addition needs the beam radiation.
 
I'm asking because I want to replace the Type 34 overhang component with an Excel lookup table with transmission values of a venetian blind, and I was assuming that multiplying these total light transmission values of the shade with the total incident radiation on the shade would give me the total transmitted energy, and there would be no need to know the beam radiation transmission individually as well. Can anyone tell whether or not this assumption is correct and if not, why the beam radiation is needed in addition to the total radiation?
 
Thank you in advance for your time and effort.
 
Kind regards,
 
Tom Bouwhuis

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