Perforated screen energy simulation

old forum
1

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

1 Like
2

Hi Andrea, i would try either to create a perforated surface and include it in my zone as a wall with windows (where windows are the openings of the surfaces or (better) place it as a shading context with a percntage of transparency (depending on the amount of perforation) with a year long schedule!

Hope it helps

Tasos

3

Andrea,

Adding the screen as shading context (as Tasos suggests) will get you pretty close. If you want to model the screen super-accurately, you can also use the “EnergyPlus Window Shade Generator” component to model a screen in a manner that accounts for the surface temperature of the screen. This example file includes a workflow for setting up such a screen:

http://hydrashare.github.io/hydra/viewer?owner=chriswmackey&for…

-Chris

1 Like
4

Hi Chris,

I have already used “EnergyPlus Window Shade Generator” for venetian blinds and it is a great component! Compliments!

I have two questions about this:

  • perforated screen effectiveness depends on openness factor, holes diameters and thickness. How is it possible to set these characteristics using energy plus shade material?

  • I am trying to simulate complex geometry shading device using shading coefficient approach. I have created a shading plane with “EnergyPlus Window Shade Generator” and put a shading schedule but the results are quite similar to no shading case.

Can I use this method? Is there any wrong settings?

In attached you can find the gh file and .csv

Thank you so much.

Best,

Andrea

Test1.gh (157 KB)
Louvers_shading_2020.csv (151 KB)

5

Andrea,

To model a perforated screen correctly with the window shade generator:

  1. Make sure that shadeTpye_ is set to 1.

  2. Set the transmittance of your shadeMaterial to be equal to your openness factor (using the “Honeybee_EnergyPlus Shade Material” component)

  3. Set the airPermeability_ on the window shade generator to be equal to your openness factor.

Seeing little changes from shades on the energy simulation is common. Shades really don’t have a meaningful effect on the overall room energy balance until you have low internal gains and you are in a tropical/arid climate. However, shades are very important for mitigating glare and thermal discomfort in practically any climate and program.

-Chris

6

Just be sure that the sum of transmittance_ and reflectance_ in the HB_EPShadeMat are lower than 1. Otherwise the HB_runEnergySimulation will fail.

-A.

7

Hi Chris,

Sorry if I can check this out simply by opening the definition (at home atm).

Would I be able to export an .idf file of the wind shade generated by this component?

Thanks,

Theodore.

8

Hi @chris ,

how would you achieve the same in the latest version of components? I see ep_transmittance_schedule but no airPermeability on the HB Shade component…

We’re looking at a perforated overhang similar to below, and curious about studying different openness factors…

Thanks in advance for any insight you can offer!

image
image1628Ă—1074 248 KB

9

Hi @jakechevrier ,

The case in your photograph seems to be different than the one that I was originally addressing with those comments on the old forum. Those original comments were intended for the case that the perforated screen is directly in front of an exterior window and the screen might hinder airflow in addition to blocking the sun. For your perforated canopy there, I would just model it as a HB Shade and I would try to match the transmittance schedule value of the shade to the openness percentage of the perforated screen.

Alternatively, if you don’t want to go through the whole process of making a schedule just so you can set the transmittance of the shade to a single constant value, you can model the canopy as an orphaned HB Aperture (that is not assigned to any parent Face/Room and is just directly assigned to the Model). In LBT 1.5 and above, we automatically translate these orphaned Apertures to EnergyPlus Shades with a constant transmittance that matches the window construction.

2 Likes
10

awesome, thanks @chris!

11

Hi everyone!

Is it possible to simulate an internal perforated screen in energy simulation (I’m currently using the 9.6 energy plus’ version)?

Thanks in advance!

Luisa