Perforated screen energy simulation

Hi everyone,

how is it possible to simulate a perforated screen in energy simulation?

Which parameters can control the openess factor?

Thank you so much.

Best,

Andrea

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Replies to This Discussion

Permalink Reply by Chris Mackey on May 2, 2016 at 9:03pm

Abraham and Theodore,

Thanks for answering Theodore's questions, Abraham, and I'm sorry for being so late to respond here. I just wanted to clarify that, if you use the "addInternalMassToZone" component, regardless of whether you input a number or an actual surface geometry, all that EnergyPulus gets is a number representing the surface area of the mass and a construction representing the material. As such, any geometry input into the "addInternalMassToZone" component is not participating in the solar distribution calculation all all of the heat the mass exchanges with the zone is though the zone air. This is clarified in the EnergyPlus input/output reference here:

http://bigladdersoftware.com/epx/docs/8-3/input-output-reference/gr...

So, if you want a given piece of internal geometry to participate in the solar distribution and have it's temperature determined through radiant interaction with the rest of the zone, you have to model your geometry as a zone surface (for example, modeling a desk against a wall as an indentation in the zone boundary). At this level of detail, though, I usually call it a day since a desk indentation is really not too different from the wall behind it thermally speaking. Still, if you produce microclimate maps of zones with interior furniture, you should plug in the interior furniture surfaces as "contextShading" to the viewFactor component as this will cause them to block sun directly falling onto occupants in the resulting thermal maps. This is a bit more accurate than not accounting for interior surfaces at all, even though the interior furniture surface temperatures are assumed to be the same as the zone surfaces behind them.

-Chris

Permalink Reply by Theodoros Galanos on May 2, 2016 at 10:11pm

Hi Chris,

Thanks for your input. I realize that the level of detail at that point is just ridiculous and I wouldn't try to model at that level. However my case is a bit more challenging since the whole roof (an expanse of around 9000 m2) has a series of hundreds of small, circular windows (imagine a pattern with small circles with center at the points of a Delaunay mesh). To top that madness off there is an interior perforated screen pattern, misaligned (on purpose) with the circular skylights.

This is the situation I find myself in and I wondered if people had any experience or ideas on how to model. I think it's fair to say that at least in terms of solar calculations this internal mass will have an impact. If however the impact on the total thermal energy of the whole zone (this is a single zone I guess) is minimal I'm up for following the sane path of WWR for the skylights.

I will test either options, if I can manage to make a few thousand windows run, and let everyone know.

Btw, I love how this can be included in the comfort maps!

Kind regards,

Theodore.