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Comment by titanomachy | Hacker News Reader

Thanks for taking the time to make this detailed write-up! You got a beautiful result, and I appreciate the spirit of sharing what you learned and helping people who are considering similar projects.

I'm glad you measured CO2. I've recently noticed I tend to get headaches when working or sleeping in small poorly-ventilated spaces, and I'm surprised how often I encounter new structures without ventilation. I guess tightly-sealed buildings are still a relatively new idea.

In the PNW you could probably be comfortable >90% of days with a cracked window, fan, adjustable shades, and a little electric radiator, but if I was doing this project I'd probably opt for the modern heat pump / ERV combo as well.

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Mini split + ductless ERV [1] would probably be cost efficient and effective for this home office. No need to get a full ducted hvac setup.

[1] e.g. https://www.pioneerminisplit.com/products/pioneer-ecoasis-50...

There isn't really any clinical evidence for CO2 levels impacting stuff beyond so called "sleep efficiency," where the effect is small (above 1000 ppm is 5% reduction in sleep efficiency) and it has the counterintuitive effect that less efficient sleep is sleeping longer, which is usually what people want. That said, placebo effects are still real.

It might be that poor ventilation gives me headaches for other reasons, and CO2 concentration is just a useful proxy that's easy to measure. The evidence seems to support this idea, whereas like you said the evidence for CO2 in isolation is pretty questionable.

If nothing else, at least a well-ventilated room expels my farts and other airborne waste products.

And people don't want to sleep longer, they want to feel well-rested. So I think higher sleep efficiency is better.

https://newscenter.lbl.gov/2012/10/17/elevated-indoor-carbon...

You are wrong about the impact of moderately high CO2 levels.

i'm aware of this one. clinical evidence - do moderately high CO2 levels CAUSE a disease? afaik no. the test in this study: they measure something real, but it is not used to diagnose someone routinely (despite what they say). they had a surprising result where performance on one of the subtests increased, and some were not affected (see https://pubmed.ncbi.nlm.nih.gov/23008272/#&gid=article-figur...). i am basically saying that, CO2 levels - do they cause headaches like the user is saying? I don't know, nobody has investigated that. 2500 ppm is very high concentration. it merits more study but not a panic.

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