Show HN: I built an under-the-door fan duct to lower bedroom CO2

9 bizzz 2 6/24/2025, 2:17:28 PM lepekhin.com ↗

Hi HN,

This is my attempt to fix groggy mornings by lowering my bedroom CO2 from 1700 ppm to ~900 ppm.

I designed a simple, 3D-printed fan duct that directs air under the door to improve air circulation.

A note on the design process: I used CadQuery, a Python library for creating parametric 3D models. I didn't know tools like this existed and highly recommend it if you can program; it turned out to be more convenient than manually iterating on prototypes in a GUI.

The project is open source and the post explains the full build. Happy to answer any questions.

Comments (2)

turtlebits · 3m ago

Generating negative pressure in a room isn't great for fresh air. You'll be sucking air through any opening- wall outlets, floor registers, ceiling light fixtures, gaps in baseboard trim, etc.

Might be simpler to augment your fresh air intake with a fan.

matthewfelgate · 3h ago

Thanks for sharing, this is interesting to me.

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Show HN: I built an under-the-door fan duct to lower bedroom CO2

Comments (2)

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