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

(www.lepekhin.com)
64 points bizzz | 1 comments | 24 Jun 25 14:17 UTC | HN request time: 0.578s | source

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.

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ahaucnx ◴[24 Jun 25 23:12 UTC] No.44372068[source]▶
Achim, founder of AirGradient here.

Nice to wake up and see a hacker news post benefiting from our open source air monitor designs, especially with the original design that we started with so many years ago! Makes me realize how much AirGradient developed since these early days.

Did you consider linking the fan with the CO2 data and making this a demand controlled system? Like you control the speed (or just switch on / off the fan) based on CO2 levels?

I think this could have a few advantages in terms of energy savings, noise level etc.

replies(1): >>44374199 #
1. bizzz ◴[25 Jun 25 06:35 UTC] No.44374199[source]▶
Achim, AirGradient was the key that unlocked this whole project for me, so thank you for creating it. Also, I see that you're still so active in the forums helping users (including me) out, double kudos!

That's a great suggestion about making it a demand-controlled system! It's definitely on the long-term roadmap. Right now, though, my system is still a bit underpowered for that. I'm in an "all fans on" mode just to get the numbers down to a barely reasonable level. If I could easily get the CO2 to a steady 500-600 ppm, then absolutely, dialing it back automatically would be the next logical step.

So, my immediate focus would be on improving the raw efficiency. Following a great suggestion in this thread (https://news.ycombinator.com/item?id=44369469), I plan to design a new mount to put a fan directly on the trickle vent itself to actively pull fresh air in. It feels like a more direct approach, and I'm curious to see what that does to the numbers.