I’d like to share our newly developed plugin with you, which might serve as a great complement to Ladybug Tools (especially Butterfly 
) and help everyone out.
Carbonfly is an easy-to-use Python library and Grasshopper toolbox for indoor CO2 CFD simulation, based on OpenFOAM and the Windows Subsystem for Linux (WSL).
Key Features:
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Indoor ventilation CFD: Run steady-state and transient simulations of CO2 transport, airflow, and buoyancy-driven temperature.
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Rhino-to-CFD in “one click”: Use Rhino/Grasshopper geometry. Carbonfly handles meshing and other setups - no OpenFOAM text files to edit.
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Plug-and-play boundaries: Presets for inlets, outlets, natural ventilation, and dynamic respiration etc., with sensible defaults you can tweak.
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Fast what-if studies: Change flow rate, supply temperature, CO2 concentration, and diffuser placement and quickly rerun for comparison.
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Visualization-ready outputs: Exports a standard OpenFOAM case for viewing CO2 / velocity / temperature / pressure etc. in ParaView.
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In-Grasshopper post-processing & IAQ assessment: Directly read OpenFOAM results inside Grasshopper for visualization and CO2-based Indoor Air Quality (IAQ) assessment based on different standards.
Workflow overview:
Post-processing in ParaView (Dynamic Respiration):
Post-processing in Grasshopper, including IAQ assessment using EN 16798-1:
Carbonfly is free and open source! See our GitHub Repo: https://github.com/RWTH-E3D/carbonfly
Video tutorials are also provided to help you get started:
I would greatly appreciate any suggestions or feedback!! 
Btw, I’m very thankful to Butterfly , which was my gateway to OpenFOAM! 