I built an under-the-door fan duct to lower bedroom CO2
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.
I built an under-the-door fan duct to lower bedroom CO2 launched on June 24, 2025 with 64 votes, #513 of 7,999 launches that month and more than 95% of that year's launches. The site was still online in September 2026, 1 year on.
In plain words
This is an open-source 3D-printed fan duct designed to improve bedroom air circulation by directing airflow under doors, reducing CO2 levels from around 1700 ppm to 900 ppm to address grogginess. The maker used CadQuery, a Python library for parametric 3D modeling, to design the duct, highlighting it as an efficient alternative to traditional CAD software for programmers. The full build instructions and design files are available open source.
written from the facts on this page · September 2026
From the sources
Thoughts on life improvement
It all started with a comment from my doctor. He told me that, ideally, I should wake up like Mickey Mouse: bright, energetic, and ready to leap out of bed. I thought about my own mornings. The reality was a slow, groggy 30-minute crawl out of sleep. Mickey Mouse? I was more like a grumpy bear waking up from a long hibernation 1 . Then one day, the ventilation failed in my office. After a few hours in the stuffy air, I had the exact same groggy feeling and a splitting headache. The pieces clicked into place. My office felt just like my bedroom in the morning. The enemy was CO2. My bedroom was the perfect trap. As a light sleeper in the city, I seal it for silence. The window is closed to…from lepekhin.com
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