HB Energy 1.6.0 Import LBNL IDF as EP Construction

Hi all

I have previously used the HB Legacy package, where I can import an LBNL BSDF IDF into my model and use it as an EP Construction in window/shading. However, I can not find a solution to import BSDF IDF in the new HB 1.6.0 to use as EP Construction. Is this functionality not included in the new version? And are there any workarounds for this problem?

At the moment, I am testing to make a dummy construction in the “C:\Users[USERNAME]\ladybug_tools\resources\standards\honeybee_energy_standards\constructions\window_construction.json” file and add the IDF BSDF as txt in additional string. But without any success.

Thanks for the help

Try C:\Users\[USERNAME]\AppData\Roaming\ladybug_tools\standards\constructions\

You can drop IDF files exported from LBNL WINDOW directly into that folder, @rn , and they will automatically be loaded into your standards library when you start Grasshopper so that you can assign them via their E+ name to Honeybee geometry.

However, there’s no support for BSDF window constructions through this pathway (only the “spectral average” IDFs). Still, there’s full support for window frames this way.

If you ask me, the BSDF specification is overkill for the vast majority of energy model applications and the only places it’s really relevant is in detailed thermal mapping studies or cases where you really need to get the temperature of the floor slab correct (eg. Certain radiant slab systems). If you really need the BSDF simulation in E+ right now, you’ll have to get it by editing the IDF.

Thanks, I will look into that. The reason for using the BSDF is that the Shading system I am using have a strange structure, which I only can model as a BSDF at the moment.

Best Rasmus

What is the metric that you are trying to calculate from your simulation, @rn ?

If it’s just energy usage, you’re probably fine just trying to match the overall average transmittance through your shading system or maybe applying a shade transmittance schedule to a honeybee shade that is in front of your Aperture. But you don’t really need to model the separate direct vs. diffuse transmittances that BSDF is doing unless you’re running a thermal comfort map or coordinating it with some radiant system or something like that.

That’s just my suggestion. Editing the IDF is also a route to try, especially if you want to prove to yourself that a simpler representation of your BSDF gives you effectively the same energy use as the complex BSDF one.

Hi, I am calculating HVAC energy usage and thermal comfort with different shading devices. The BSDF represents a complex fenestration system. It’s a microsystem placed in the middle of the window system that is highly angular dependent, which as far as I am concerned best represented with a BSDF otherwise it should use some spectral data that is split based on the angle.

So my general problem is that I am using the Honeybee/Ladybug package in Python directly where I am importing the window system through LBNL python API to create glazing/shading systems. But I am only using BSDF in cases on angular-dependent shading systems. My workaround is the moment that I create the code for the glazing systems myself and add them to the IDF that is created through the functions in the honeybee package however would be easier if I could combine them from the start.

But I will look into maybe removing them, have just always seen the BSDF file format as the answer, but your answer has made me look more into that.

Best Rasmus

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