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Comment by cycop | Hacker News Reader

I have a desk CO2 monitor , it averages between 800 to 1000 in my home office during the day. Anyone else monitor their own environment or know if their office does? Are people even interested in this type of monitoring?

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I measure CO2 at home.

When the meter hits ~1000ppm, I open all windows until the level is below 500ppm again. Otherwise they stay closed to keep humidity in.

My office has forced ventilation, the level there is usually around 700ppm all day.

I'd be interested in measuring NOx levels, sadly I don't have a sensor for that. A few people in the office like to open windows for comfort, our air tends to feel a bit stale, even though it's continuously exchanged. My theory is that by opening the windows we let NOx in, which causes the staleness and in high enough levels irritates eyes and throats.

I was monitoring indoor CO2 at my home. It definitely swings in the 800-1000 range, especially if I keep the door to the rest of the house closed or mostly closed. But if I leave that door open, it often drops to 600 or less during the day when I'm probably not adding to the CO2. If I open a window it drops to about 430 in a few minutes. It's noisy where I live, though, so I mostly don't ventilate much externally now and live with it.

I monitor air quality in rooms in my home using Awair Glow sensors. They log temperature, humidity, CO2 (ppm), and VOCs (ppb). When CO2 or VOCs hit 900+, I start opening windows to encourage airflow.

Awair Glow doesn't measure CO2, it infers it based on other readings. The results of doing this way are never accurate.

I monitor my office. It works its way up to 1300-1400 ppm during the day. At the start of the day it is the outdoor baseline.

Wait, GP said 800-1000, you have it at 1300-1400... isn't 1000 like the headache line? Shouldn't it be around 400-600 in a healthy environment?

Edit: Looking it up, the Wikipedia article on CO2 has the following to say on the topic:

> A study of humans exposed in 2.5 hour sessions demonstrated significant negative effects on cognitive abilities at concentrations as low as 0.1% (1000ppm) CO2

> Another study observed a decline in basic activity level and information usage at 1000 ppm, when compared to 500 ppm.

So 1ppk is definitely bad. Another datapoint is from 5ppk:

> At [5000 ppm for an 8h period, the] International Space Station crew experienced headaches, lethargy, mental slowness, emotional irritation, and sleep disruption.

Thanks for the concern. Yes it is bad, which is why I built a CO2 meter. I need to get alerts to ensure either I get more air to me, or I leave the office.

How can one get rid of the CO2 around your home office/desk during the day?

Open a window

Yeah so I'm of two minds about this: I want fresh air, and I don't want to waste energy (not for the money but for climate reasons) by opening a window all day and trying to heat up 0-10°C outside air to a temperature that is comfortable when all you do is sitting still (22°C).

I guess the main heat retention is in the objects and not so much the hot air, so the strategy would be to vent through and replace the air in as short as possible a time every few hours?

A long-term solution is to install a ventilator with a heat exchanger. Outgoing air on one side of a thin metal plate warms up incoming air on the other side. This covers about 50% of the temperature difference for free.

I didn't know that was a thing. It looks like most are 250 euros or even double that. It's a fan with a metal plate right?! Or is there some built in fridge-like construction to exchange the heat?

There is also one result for 50 euros (1.7/5 star average) but alongside the 250-500 euro results that doesn't seem like it'll be the same thing.

You want an ERV or HRV - many new "air tight" houses use them, they have a ceramic core which mixes interior and exterior air to bridge the temperature gap. (and humidity in the case of an ERV)

Ventilation, and not just recycling indoor air.

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