Hi all,
I’m trying to use HB Airflow Network component of HB 1.1.0.
Regarding Wind driven ventilation,
Can I set wind pressure coefficient for each window manually?
I want to put the result of Butterfly-CFD into Airflow network simulation.
Thanks,
Naoki
Hi Naoki
I’m facing the same question. Have you get the answer and would you like to share it with us?
The current iteration of the AFN components autocalculates the wind pressure coefficients based on assumptions about the geometry of the building (basically assuming it’s a rectangular prism defined by user-inputs of axis angle, height relative to width, and aspect ratio).
Therefore, you can’t include custom wind pressure coefficients with the current HB AFN components, but you can modify the .idf file to include them, although I don’t remember how to do this exactly.
Thank you very much Saeran. I found that after yesterday and reinstalled the new version ladybug. 
Hi ! I was wondering if it was now possible to set the wind pressure coefficient for each window manually into HB Airflow Network component with HB 1.4.0 ? @SaeranVasanthakumar @chris
Not at this point, Chris will be the person to ask for future plans for this component.
What @SaeranVasanthakumar said.
If you really wanted to customize things, you can manually set the wind pressure coefficient of each Aperture using the Ladybug Tools SDK inside a GHPython component. Here is the most relevant class for trying to do this type of customization. But, if you are looking for some streamlined workflow that takes some type of CFD result and translates that into something that helps out the EnergyPlus AFN, that’s probably far in the future after we have refactored the Butterfly plugin.
Hi Naoki, I know it’s been a long time since you posted this question but I was wondering if you could briefly explain how you calculate the wind pressure coefficient with Butterfly. I am particularly confused about the wind velocity that I need to use as a reference for all wind directions (is it a constant number or does it depend on the weather file?). Moreover, did you calculate the pressure at the center of each opening and then use the Cp formula to calculate it? or is there a more straightforward method?