I got a CO2 meter out of curiosity. They are, indeed, about US$150. I get a little under 500ppm indoors.
Incidentally, humans can tolerate much higher CO2 levels with accommodation, but, as with altitude, it takes days. The US Navy submarine people have done considerable work on this. So this is not a global warming issue.
Real CO2 sensors are still about US$60 as a part. The standard sensor has a heating element, and uses about 75mA, so this isn't suitable for battery operation. 1mA sensors are now available, but for US$160 or so. This cost problem is holding back widespread use in HVAC systems. HVAC systems for rooms where the people load varies widely (classrooms, offices, hotel function rooms, restaurants) should have a CO2 sensor to tell how much outside air you should be pulling in. But outside of hotels, they're rare.
Cheap "air quality sensors" measure volatile organics, which is something else entirely.
Windows open? Drops into 600ppm range. GF and I at home with closed windows and HVAC off, usually climbs into 1200pm range. Gas oven on? Easy to get over 3000ppm if there's no ventilation on.
> But outside of hotels, they're rare.
I haven't made it a point to look in all of them, but I've seen quite a few in microbreweries in the room they do their brewing. Not sure if required by law, but it's generally a good idea.
Though it really depends on what you want to do with the data, I can really recommend to use esphome in combination with homeassistant/influxdb/grafana. You can configure the sensors with a simple yaml file, compile and upload to the chip and then add it to a homeassistant dashboard. Long term trends can be queried from influxdb and presented in a grafana dahboard
Some of the makers of the VOC matters suggest that they are better for this purpose than CO2 as they detect exhalation and off gassing. And maybe body odor, too.
Every meeting room in our office building has a little meter in it which rotates through displaying three different measurements: temperature, relative humidity and CO2 ppm. Most of my colleagues are surprised when I point this out to them.
The floors of our office that I sit in has two sizes of meeting rooms: one for eight/nine people and one for three people. Free meeting rooms are scarce during regular hours, so sometimes we cram in to three-person room.
It's fun watching the CO2 measurement climb from 800 to 1400. Supposedly 400 ppm is outdoors, 800 ppm is indoors and anything higher is a little unusual. I have fun pointing out the reason why we are all feeling sleepy and docile towards the end of a meeting is because of the CO2!
The trajectory the Keeling Curve (+3ppm/year) is on, the dumbing down of (human) cognitive abilities seems to be challenging climate change sooner than I thought on what is the more immediate problem to civilization.
The effect mentioned in this article is certainly not suffocation. 2000 ppm of CO2 is about 0.2% of the air, and doesn't signficantly reduce oxygen levels. It's a real problem, but calling it suffocation is pretty dumb.
This is possibly even a more serious problem in tightly weatherized bedrooms. I was in a rehabbed house tightly weatherized by the contractor (to meet a typical building code). It had radiant heat. When my wife and I sat in the bedroom for 1 hour, a calibrated CO2 sensor showed levels rising to 1600 ppm. (Humans put out lots of CO2). Sleeping 6 - 8 hours in that environment is very likely to cause cognitive impairment the next day. So if you're in a "tight" house, make sure to sleep with the windows open!
Raising the question of course, of why then tightly weatherize the house? Well, so we can say, we're being environmentally responsible, of course!
10% (100000 ppm) concentrations can cause unconsciousness or death even if you have enough oxygen.
It is because we don’t only need to get oxygen from air but also to exhale CO2 as waste. And the higher CO2 partial pressure is the harder it is to get rid of it. Eventually killing us.
Or get yourself some sansevieria trifasciata plants. Depending on the size of your bedroom, 3-4 should so it (about 1 per 100 square feet of room). They'll convert CO2 to O2 all night - and clean the air a bit as well. They are also easy to maintain.
They use of a different mechanism to power it by delay. They use a second CO2 fixation pathway known as Crassulacean Acid Metabolism (CAM). Basically they "store" the energy by day, then open up at night and to their thing. Only 5-6% of plants do it this way and, IIRC, almost all of those are succulents or desert plants. This pathway helps preserve water.
Also, most "kid" bedrooms are around 10x10 or so, but some master bedrooms can be rather ... large. I said 3-4 to cover both not being the only one in there and the size of the plants. The tests are done on or projected to full-size mature plants, but if you go to the store and buy them they are rarely full size. They'll range from 6-8" babies to about 1/3-1/2 in size (1-2'). For the "full effect" from the reports they size based on a 4' tall plant.
Is that accurate though? So I live in recent new construction, and run the house fan for long periods of time/overnight, and the power bills are still the lowest I’ve experienced. Fans take very little power to run, compared to burning gas/running ac to achieve desired temperature...
Well the people who make a living projecting high CO2 levels would be surprised, since that is about 50% higher than their recent highest projections. Some older predictions had the levels in 2100 up to 800ppm, but the IPCC has been revising them downward for quite some time now. This is in part because we've had them for long enough to see they haven't been accurate, and because the "worst case" ones don't use any theory they just calculated a straight based on the highest rate they find. These predictions have consistently been higher than actual data. So the likelihood that we'd hit 1000ppm by 2100 would mean they'd have to have predicted around 1100-1200 ppm by then, but their worst case is around 800ppm. Which, based on their historical performance would indicate the worst case is more akin to 600-700.
In high school I remember being consistently very tired in certain classes. One of them was health class, which replaced phys. ed. for one quarter, meaning that an entire gymnasium worth of students was crammed into a classroom. Others such classes were internal classrooms with no outside walls, and hence no windows. I suspected CO2 was an issue at the time but obviously had no way to prove it.
Reversely, I was surprised at how healthy (tall, notably, and a healthy skin) Australians are compared to France. I highly suspect that Australia has proper air ventilation in classrooms and we don’t in France. In France it is common, for a class, a meeting, and and even in a theater or music show, to cram people in a room, and not worry about ventilation. People complaining will be seen as weak.
I wonder whether proper air venting through school increases the global IQ and total skills of students.
But if the air is so much charged with CO2 we feel it and we end up opening the windows it seems? At least at my job meeting rooms windows are systematically opened between meetings.
This has been why I have enjoyed living and working in Europe (DE and CH): high-quality windows to be opened at a moment's notice at home or in the office.
I agree, the small “people” in other continents don’t truly enjoy the atmosphere in the same way that we do, with the highest quality windows demonstrating the apex of European craftsmanship. Air just doesn’t feel the same when it’s being wafted through a lesser window in an inferior continent.
I heard that other places don’t have toilets, opening windows, or even the opera!
They may have been referring to "tilt and turn" style windows (https://www.youtube.com/watch?v=LT8eBjlcT8s) which I saw everywhere in Germany but I've never seen in the US.
I suspect this may be why I'm so tired after meetings, but I'm not sure. It would be nice to test the air in the meeting room. There are dozens of different sensors on sale on Amazon, but if I buy one, how do I know if it's correct?
Some people are more sensitive to this than others. For me, being in a badly ventilated room feels as if someone is trying to suffocate me with a pillow.
Not being able to sit by the window and keep it open whenever I need it is yet another thing that I hate about open spaces.
You need about 1 sansiveria per hundred square feet or so. NASA has spent quite a bit investigating the efficiency and effectiveness of a wide array of plants for CO2 -> exchange. In an office you'll want plants such as bamboo palm, english ivy, peace lily, boston fern and a few others as they do their work presdominantly by day and sequester oxins such as formaldehyde and benzene.
They don't have to fully supply everyone's oxygen to be effective, nor do they have to fully consume your CO2. That said, you'd be surprised at how well some of these will do just that. As a rule of thumb, about four mature sansevieria trificiata will convert as much CO2 to O2 as a single human does on a daily basis. But with those they are storing the CO2 by day and releasing O2 by night so while they will sck up the CO2 in your office by day, you won't see the O2 "come back" in that same time - at least not significantly so.
Others such as some of the palms and lillies, and a few ferns, would do that same "effort" but in the daytime. Even then, in the context of offices and other rooms in this discussion the part to look at is their CO2 consumption, not the production of O2.
Some plants, such as Ficus benjamina are very effective. One (or more) of those with a total leaf surface area of 1 square meter can take a closed room from 2,000ppm CO2 down to 400-500ppm in one hour (variance based on temperature and light levels).
I meant outside the room. It's hard to saturate a room in CO2 with a window opened and ventilation. Many big cities are working to improve air quality
Having all kind of material to improve locally and artificially the air, like air-conditioning, feels like a temporary hack for a bigger problem, adding even more pollution in the equation
I always suspected this. I recall several times in crowded lecture halls feeling drowsy and uncomfortable. My theory was co2 but I didn't know enough about how it works.
Interesting to think though about the whole co2 thing, if we keep burning fossil fuels we won't be able to think properly anymore?
Incidentally, humans can tolerate much higher CO2 levels with accommodation, but, as with altitude, it takes days. The US Navy submarine people have done considerable work on this. So this is not a global warming issue.
Real CO2 sensors are still about US$60 as a part. The standard sensor has a heating element, and uses about 75mA, so this isn't suitable for battery operation. 1mA sensors are now available, but for US$160 or so. This cost problem is holding back widespread use in HVAC systems. HVAC systems for rooms where the people load varies widely (classrooms, offices, hotel function rooms, restaurants) should have a CO2 sensor to tell how much outside air you should be pulling in. But outside of hotels, they're rare.
Cheap "air quality sensors" measure volatile organics, which is something else entirely.