To account for specular reflection (both solar and visible daylight) you also have to make sure that your Shading Surface Reflectance input object specifies that at least some of the surface is glazed (Field: Fraction of Shading Surface That Is Glazed > 0.0), and that a Field: Name of Glazing Construction is included. You will have to define a glazing construction that has properties that mimic your medallions, so you may have to play around with reflectance and transmittance values.
Rob
======
Ellis, Peter wrote:
Hi Marzia,
I think you can model the medallions as shading surfaces and then add reflectance properties using the Shading Surface Reflectance object (see the documentation)
. This object allows for specular (beam-to-beam) reflectance which is what I think you are looking for. It looks like it should work with the Daylighting: Detailed calculation, but I'm not 100% sure. You'll have to make sure you use the solar distribution options "withReflections". One other thing to keep in mind is that you are not going to have reflected glare all the time. My experience is that there are only certain times of day and year where the beam reflection will line up just right to bounce into your zone. And depending how large the window aperture is and what time step you are using, you might miss the reflection altogether because it is occurring between time steps. You might want to consider using a program outside of EnergyPlus that will do full ray tracing and daylighting analysis to study just the times of day/year where there is a glare problem.
Good luck,
P
From:
EnergyPlus_Support@ [mailto:yahoogroups. com EnergyPlus_Support@ ] On Behalf Of marziasedinoyahoogroups. com
Sent: Monday, June 16, 2008 4:49 PM
To:EnergyPlus_Support@ yahoogroups. com
Subject: [EnergyPlus_Support] reflective metal medallions on the facade
Hi,
I am trying to calculate the glare index for a building which has got
zig-zag curtain walls on all sides with reflective metal medallions.
The medallions are some sort of mirros on the outside of the facades
and should reflect solar rays inside the building. So I am expecting
big glare index inside.
my question is how to model reflective surface in E+.
I tried to assign them as opaque surfaces but I couldn't really change
their reflectivity.
So i tried to simulate them as single windows with high reflectivity
(0.9) and no trasmittance but still the glare index seems to low...
for the solar distribution I used both Fullexterior and
Fullexteriorwithreflections.
Thanks a lot
Marzia
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