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The bottleneck might be the air in the room

blog.mikebowler.ca

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Re: The bottleneck might be the air in the room

#411

Post by dtgriscom »

KerrickStaley wrote: post #51
w-m wrote: post #36

Earlier quoted context omitted.

I don't think you can cleanly compare this: In the study, they added CO2 to the room, while keeping O2 at normoxic levels throughout the experiment. In your meeting room, O2 levels will be dropping in lock-step with the CO2-levels rising. It may be the lack of oxygen that leads to drowsiness, not the additional CO2. But it's the CO2 levels that you can measure as a good proxy of overall air quality.

I don't think this is correct. The concentration of CO2 in air is about 0.04%, whereas the concentration of oxygen is 20%, so the partial pressure of oxygen is about 500x higher. This means that if, for example, 10% of the oxygen in a room spontaneously disappeared, it would be replaced about sqrt(500) = 22x faster through leaks in the room than a 10% spontaneous CO2 increase would dissipate. (This ignores a small ef…

I think this is (in turn) wrong. Yes: having 500x the amount of O2 as CO2 means that a 10% drop in O2 will trigger 500x as many molecules diffusing in per second as the same drop in CO2. But, each molecule of CO2 will change the relative percentage 500x as much as a molecule of O2, so isn't it a wash?

Re: The bottleneck might be the air in the room

#412

Post by gblargg »

npunt wrote: post #35
kashishgrover wrote: post #27

Oh this is absolutely so relevant and I wonder if there are any high quality studies that have analyzed driving performance against CO2 buildup in cars. Cars often ship with circulate air feature in the aircon, and people use it aggressively, nonchalantly at least where I live, having no idea about the dangers of possible hypoxia and sleepiness that might be inducing in them while driving. It is absolutely critical i…

Got a firsthand experience with this. I was dropping off my girlfriend and we stopped to talk in the car, with all the windows up. Over the course of the conversation we got more and more agitated at each other until I had a thought and pulled my Aranet out from my backpack. It was >3000ppm CO2. We opened windows and within 2 minutes all the agitation went away.

I was amazed how quickly it rises in the car with windows up and recirculate mode for the fan. There's a reason it has a fresh air mode.

Re: The bottleneck might be the air in the room

#413

Post by gblargg »

chrisweekly wrote: post #380
abixb wrote: post #290

Earlier quoted context omitted.

Fantastic, did you go for a particular "trusted" brand or just went on vibes? How should one rationally approach shopping for a CO2 monitor for home office use?

I didn't do much research, got a really basic "Temtop" model from Amazon.

I've tried several (Amazon Vine) and I would just leave them outside to be sure they reach 430 or so, and then take them in a closed room, also breathe on them several times and it should spike quickly. Opening up to verify an actual CO2 sensor is also a good idea. A few just had a tiny sensor and faked various readings based on this.

Re: The bottleneck might be the air in the room

#414

Post by bad_username »

Yajirobe wrote: post #192

I have a CO2 monitor and I don't understand one thing - it seems that CO2 increases more quickly during summer than during winter. If I close my windows it takes longer to reach 1000 ppm during winter than it does during the summer. I didn't gather concrete data on this but this is just what I eyeballed over the last few years. Does anyone know why could this be the case?

The speed of air exchange through openings in your room (windows, gaps etc) is proportional to the difference of temperature between your room and outside. The more different the temperatures are, the more intensive convection is, and convection is very effective at moving/exchanging air. In summer the difference in temperatures of your room and the outdoor space is much smaller than in winter, which subdues convection, and the stale air tends to stay.

Re: The bottleneck might be the air in the room

#415

Post by fooblaster »

thomasmg wrote: post #304
fooblaster wrote: post #257

Earlier quoted context omitted.

So is this all bullshit?

Lacking a large study, we can't know. Of course the CO2 meter companies benefit if people believe it is true.

This is kind of a bummer. I have a nice co2 meter. another reason to be skeptical of everything.

Re: The bottleneck might be the air in the room

#416

Post by Scroll_Swe »

microtonal wrote: post #375
Scroll_Swe wrote: post #223

Earlier quoted context omitted.

But if I open a window at 700ppm, so what?

Maybe you live in a place where the room temperature is the same as outside. Here in winter, it means sitting in the cold.

No I live in Sweden.

You can open the window for a bit to air out, should be done even in the winter :)

Re: The bottleneck might be the air in the room

#417

Post by Scroll_Swe »

microtonal wrote: post #374
Scroll_Swe wrote: post #158

Earlier quoted context omitted.

>With ALPSTUGA it would send already at 700ppm. "oh no I am getting too much fresh air" I get your point but come on.

In some situations it means opening a windows, with big temperature drops when it is cold outside. At any rate, this is really a weird discussion, because you can get far more accurate meters at similar price points. Why waste your money on a much worse meter?

The IKEA one looks cuter :3

Re: The bottleneck might be the air in the room

#418

Post by fuzzfactor »

hahahaa wrote: post #46
w-m wrote: post #36

Earlier quoted context omitted.

I don't think you can cleanly compare this: In the study, they added CO2 to the room, while keeping O2 at normoxic levels throughout the experiment. In your meeting room, O2 levels will be dropping in lock-step with the CO2-levels rising. It may be the lack of oxygen that leads to drowsiness, not the additional CO2. But it's the CO2 levels that you can measure as a good proxy of overall air quality.

O2 is 200000ppm so if co2 goes up 400 to 2000ppm does o2 go down to 198400ppm?

Don't neglect the 80% nitrogen which dominates proportionally.

Re: The bottleneck might be the air in the room

#420

Post by JonathanRaines »

salahadawi wrote: post #99
oasisbob wrote: post #23

There needs to be a meter for the amount of AI writing in blogposts. Same physics, same climb, same afternoon fog.

I've actually been tracking the front page of HN for AI posts for a while now: https://www.salahadawi.com/hacker-news-ai-detector This post evaluates to 99% AI generated.

Pangram claims to be super accurate. Do you know how? I understood detection is a hard problem.
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