interior air walls for splitting nonconvex zones
In real world there are plenty of cases where zones are nonconvex polygons.
It is a well known issue that energyplus cannot handle this, and it's up to the engineers designing simulation to do an alternative.
One of the best alternatives to circumvent this shortcoming is for example to split the zone into two or more convex zones, using as a separator a thin wall of air that lets all/almost all heat exchanges to occur between zones.
Following https://unmethours.com/question/13094... of course Honestly, it's knowledgeable that EnergyPlus is a complex simulation engine and documenting such into a couple of PDFs is no easy task, although there isn't easy information to be found regarding the issue of air walls, and have used this topic to check them out so, thanks.
Only question i have is about these materials you are using in Open Studio:
Material,
Air Wall Material, !- Name
MediumSmooth, !- Roughness
0.01, !- Thickness {m}
0.6, !- Conductivity {W/m-K}
800, !- Density {kg/m3}
1000, !- Specific Heat {J/kg-K}
0.95, !- Thermal Absorptance
0.7, !- Solar Absorptance
0.7; !- Visible Absorptance
So the basic idea here is using this Air Interior Wall surfaces to split non-convex L buildings/zones, or polygons with holes (aka interior rings) that create nonconvex shapes.
How? Adding an extra interior wall to L corners (this is done using computational geometry) and or ring corners, and then assigning them air wall material for the zone interface surfaces (one for each contiguous zone).
The issue with this material which would be supposed to mimick somehow the properties of airflow that seem not matching and if you can explain would be welcome are the following properties:
Roughness: shouldn't it be smooth (it's the most possible resembling to air layer or surface)
Thickness: shouldn't it be minimal (in documentation they do not recommend lower than 0,003 so 0,001 for example)
Solar and Visible absorptance shouldnt it be lower to match the material properties accordingly.
EDIT (10/03/2020):
In a response to a question in comments, due to its potential interest in more people checking this topic here is added further information.
Convex zone zone having a floor polygon projection (footprint) where each vertex connects to all others through a line that is always inside the polygon (i use this definition because i work with computational geometry and actually this is one way to compute if it is convex with algorithms, there are other definitions, like for example all external angles must be above 180º)
Non-Convex Zone opposite of convex (an L-Shape is one of the most common building non convex zones).
Why does this matter?
EnergyPlus engine part that treats beam solar radiation and reflectances from exterior surfaces that strike the building and, ultimately, enter the zone is not prepared to handle non-convex geometries because in these cases it would require further interactions that where not considered, specifically due to Interior. This engine part is defined in ...
@EngFranc What exactly is energyplus unable to handle in nonconvex zones? I know there are some problems with simulating lighting from fenestration, but I've never gotten a clear answer as to what all the problems are. Could you please add that to the post?
@mldichter ok i will edit it and since you asked i will also add a solution i am adopting to deal with these in a good fashion.