Optical / thermal simulation of subway elevated platform

Hello to everybody,
I want to simulate the thermal environment, light environment and human thermal comfort of the platform of the subway elevated station, but this model is a semi open space, not a completely closed building.

  1. I want to ask if this arched model can be recognized as HB Zone by honeybee,or what better modeling methods can be implemented.

  2. I don’t know whether honeybee can simulate this type of building. At present, I think of two methods:

The first is to set both ends of the building as air walls;

The second is to set large-area permanently open windows in the two short open parts of the building.

But I don’t know if the air wall can let wind, light and heat radiation penetrate the air wall.It is also unclear whether permanently opened windows can also allow the natural transmission of outdoor wind, light and solar radiation.

Subway elevated platform.gh (495.5 KB)


Re: The arch
Yes the arch can be modeled in HB-Energy. The best approach is probably to break up your extruded geometry into discrete floor, wall and roof geometries that can be defined as Honeybee Face components[1] with manually defined, corresponding type arguments.

Re: Simulation of wind and radiation:
If you want to use an energy simulation to model thermal comfort, I think an always-open window model would capture an open enclosure adequately. An airwall is typically used to delineate interior boundaries so would not be appropriate for your exterior boundary. I would double check the way the selected solar radiation (i.e. FullExteriorWithReflections or FullInteriorAndExteriorWithReflections for shading) and airflow (i.e. simple wind speed-based airflows versus a wind pressure-based Airflow network for ventilation) is modeled in the EnergyPlus references[2] just to ensure you understand what abstractions are being made. There are increasing computational costs associated with increasing model realism that may not be worthwhile to pursue at an early stage.

I would suggest using Radiance for modeling the short-wave solar radiation impact on comfort, like in the UTCI Comfort Map component[3]. That way you can capture the diurnal swing of the concrete platform’s thermal mass with EnergyPlus, while incorporating the detailed short-wave radiation dynamics of Radiance. Since there’s no glass, you don’t even need to consider the portion of short-wave radiation that is absorbed by windows that (I believe) doesn’t get modeled by the Radiance model.

Edit: This paper by Chris, Theodore G., and Mostapha actually answers your second question in a lot more detail: https://www.ladybug.tools/assets/pdf/BS2017_260.pdf.

[1] Face - Honeybee Primer
[2] EnergyPlus Web-Based Documentation | Big Ladder Software
[3] UTCI Comfort Map - HB-Energy Primer

1 Like

hi, SaeranVasanthakumar.
Thank you for replying to my question in your busy schedule.
I understand the points you mentioned, but I still have questions about this modeling method: because the roof of this model is an arch, and the roof will open windows to meet the lighting needs of the platform. Can I draw an arc, and can ladybug & honeybee recognize this arc?

A colleague of mine said that the figure recognized by honeybee must be a polygon, and the fewer sides of the polygon, the better.

I would like to ask how to draw this vaulted roof so that it can be recognized by plugins such as honeybee & radiance…

1 Like

Hey omen,Your colleague is right.
HB-energy currently only recognizes polygonal models. When modeling, the entire plane can be scaled to 0.9999 times (Zoom out so that it does not overlap the edges of the polygon ) and added to the model as a window part.
The second method, as illustrated in your picture, is quite reasonable.

This is a model of a complex skylight that I have made. You can follow this method to make it, which should be helpful to your problem.