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What does OS do when you define an air wall?

asked 2015-06-06 18:49:15 -0500

updated 2015-07-12 14:22:19 -0500

I'm trying to figure out exactly what openstudio does when you use the Air Wall Construction. I'm looking through the outputed idf, and don't see the air wall construction in there. Is it creating a material with very high U value? Is this an opaque construction material? I'd like to know as if its opaque then it will not be suitable for daylight and detailed solar gain analysis. I've always modeled internal openings in E+ by creating a special glazing material with close to 100% transmittance, but maybe I can skip this tedious step.


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answered 2015-06-09 10:43:42 -0500

Currently, air walls are translated to a single layer of drywall in EnergyPlus simulation:

The grand plan in OpenStudio is to eventually add parameters to the OS:AirWallMaterial such as:

  • Create Interior Window (True/False)
  • Zone Mixing Per Area (m^3/s*m^2)
  • EnergyPlus Simulation Material (Name of other material)

These parameters would control how air walls are translated to EnergyPlus. However, we have not gotten to this yet.

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Thanks - this is very helpful.

Hayes Zirnhelt's avatar Hayes Zirnhelt  ( 2015-06-17 13:06:52 -0500 )edit

answered 2015-06-09 09:31:22 -0500

From a Radiance/daylighting perspective, the OpenStudio Air Wall construction is intended to be used for space and thermal zone boundaries that have no architectural counterpart. As such, surfaces with that construction applied are ignored by the Radiance Forward Translator. I think this is exactly what you want and will work better than the 99.99% VLT glass trick.

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Hi Rob, I saw your tutorials, excellent for traineers, but I have doubts. Imagine a L shape small building and I want to analyse daylighting performance in two adjacent zones separated by air wall. Should I put the illuminance map crossing the air wall? Or is it mandatory 1 for each zone? Tks so much!

luis melo's avatar luis melo  ( 2016-04-11 15:50:55 -0500 )edit

Hi again, after run simulation I suposed that first alternative is impossible....Am I correct?[openstudio.radiance.ForwardTranslator] <0> Secondary DaylightingControl Daylighting Control 3 is not supported by Radiance, it will not be translated.

luis melo's avatar luis melo  ( 2016-04-11 16:00:47 -0500 )edit

Unfortunately because we are trying to maintain some parity with the EnergyPlus simulation you're forced to use one illuminance map per zone. The best approach here will depend on what you're looking for, daylight metrics or lighting schedules. I realized the answer is probably "both", but in this case you may have to pick, until we can support this better. If the L-shape is a single zone, I would consider making it two zones, frankly.

rpg777's avatar rpg777  ( 2016-04-12 12:09:26 -0500 )edit

Hi Rob, Thank you very much for help. I followed your instructions and the simulation works. Now, I need to learn about energy consumption analisys, with Openstudio. Can you show me any tutorial?

luis melo's avatar luis melo  ( 2016-04-13 09:54:31 -0500 )edit

Do you mean in the context of the Radiance measure? The main point of the measure was to calculate new electric lighting schedules based on the Radiance daylight availability data, so you could look at the delta in lighting energy use using Results Viewer, etc. The measure does also output a bunch of other interesting data such as daylight metrics, but these are still a bit buried, unfortunately. But if you look in the measure's directory, under radiance/output/, you will see daylight_metrics.csv and several others.

rpg777's avatar rpg777  ( 2016-04-13 14:54:48 -0500 )edit

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Asked: 2015-06-06 18:49:15 -0500

Seen: 2,417 times

Last updated: Jun 09 '15