I recently started measuring CO2, Radon, PM (particulate matter) 1.0, PM 2.5, VOC, humidity, temperature, and air pressure with the Airthings Wave connected device.
I have learned a lot while using it for a couple weeks. First, making a fire in your fireplace is great for ambiance but drags air quality down substantially. It eats up oxygen a lot and make the CO2 increase sharply. It also causes very high spikes in particulate matter (both 1.0 and 2.5 micron) from putting the burned byproducts into the air.
I also started improving the energy efficiency of our heating system by fixing spots in the house where cold air comes in. While this results in less energy used to heat the home, it causes CO2 to increase because there isn’t anymore large holes to bring fresh air in. This device helped me learn that CO2 is and energy efficiency are circular problems. The tighter my house is, the more I need to focus on ventilation - exhaust out and fresh air in. It sounds complicated but for me it just means opening windows throughout the house for about 15-30 minutes per day. That alone makes a major difference on everything - Radon, PM 2.5, PM 1.0, CO2, etc.
Lastly just want to mention that it’s amazing to me how fast CO2 levels can rise with just my husband and I in our living room watching a movie. Good ventilation is something I definitely recommend everyone start measuring and working on.
Building tight prevents conditioned (heated in winter, cooled in summer) inside air from escaping, causing you to lose/waste money. It also prevents bad outside air (bugs, pollen, dust, car pollution, too humid/dry/cold/hot) from coming in.
Ventilating right means taking stale air from bathrooms (humidity) and kitchens (cooking VOCs) and exhausting it, and at the same time bringing in fresh air from outside on your terms: through filters and tempered to match inside conditions. This is usually done with HRV/ERVs.
Harder to do with older homes that need to be renovated, but now part of the building code for new builds in many areas (ASHRAE 62 defines ventilation volume/rate requirements).
Not exactly. What you heat is the inside of your rooms, and a significant part of that heat can be felt as infrared radiation. When you ventilate in a quick and intensive manner, you exchange the air, which becomes cold for a few minutes but you do not cool down the room - because that takes longer. And the cold air has very little mass, so it is easy to re-heat again, and will be warmed by the walls etc.
The energy stored in your walls is much higher than the energy stored in the air. Swapping out all the air for cold one will reduce the total energy stored in your house very little. The walls will reheat the air. Same with letting AC air escape for a minute or two.
Buy a co2 meter. You have to have windows opened for much more than 5 minutes. Aaaand you have to open them every 40 minutes, even when you sleep. Good luck with that.
For smaller homes switching from convection to infrared heating helps a lot, heating the surfaces instead of the air, means that letting the air mix by opening a window is less of a problem.
There's a ventilation technique that uses heat exchangers to warm the air coming into your house and vice versa (can't think of the correct name for it right now). Something to look into to have the best of both worlds.
It might help if “enthalpy” as used by HVAC people was closer to what “enthalpy” means in thermodynamics. The closest I can come is that HVAC enthalpy is the enthalpy of the air plus the enthalpy of vaporization of the water vapor in the air.
This is an oddly named but somewhat useful concept for air conditioning because water that condenses onto an A/C coil delivers its enthalpy of vaporization to the air conditioning system. So you can add “latent heat” to “sensible heat” and get a sensible answer.
But this is all a bit silly in the winter. In the winter, the primary consideration is not the energy cost of vaporizing the water in the air. It’s the amount of water in the air, how to get it there, how to keep it there, and how much humidity is safe for the building envelope. I doubt anyone measures humidity in units of BTU/cubic foot.
My local contacts in Berlin have called it Lüftschlag — air punch.
(Although, who knows, that might just be a weird localism, just like “Guten Nacht, schlaf gut, träum süß von sauren Gurken.” which I was taught in Köln and nobody else I’ve talked to anywhere in Germany recognises, though when I say I learned it in Köln they all go “Oh, Köln, yeah, they’re all crazy like that”.)
As a Kölner by birth that localism does ring a faint bell though I wouldn't have said it's a Cologne thing if you had pushed me on it. We do have plenty of localisms due to the historical proximity to France though, and it always amuses me that "Plümo" (duvet) for example is completely unheard of in most of the German-speaking world and is usually replaced with the far less graceful and to me frankly confusing "Oberbett".
But the general term, as a verb, is "Lüften" or specifically "Stoßlüften" for the shorter form that is often mandatory for apartments with modern insulation but lacking a proper vent system to prevent mold.
On a sidenote: an interesting folk etymology exists for the Rhineland word "Fisimatenten", meaning something like "shenanigans", deriving it from French "visite ma tente", literally "visit my tent": the claim is that mothers would advise their daughters to avoid "Fisimatenten" because French soldiers during the Napolean occupation might invite them (in French) into their tents for, well, shenanigans.
> But the general term, as a verb, is "Lüften" or specifically "Stoßlüften" for the shorter form that is often mandatory for apartments with modern insulation but lacking a proper vent system to prevent mold.
Exactly that.
To add, problems with mold are often due to insufficient insulation in some patches of the wall (like near windows), combined with humid air and insufficient ventilation. A properly insulated house should not form mold. But it is necessary to get humidity out, that's correct.
there are quite a few replies of people that reported how they were not familiar with the concept.
And I have to underline how the evolution of building practices (again that depends greatly on different countries/local uses) generally speaking tends to make houses more airtight than before, so that ventilating should be more needed nowadays (with the exception of mechanically ventilated houses).
> it causes CO2 to increase because there isn’t anymore large holes to bring fresh air in
Obviously you need the double-entry exchanger: Air comes in at 5°C and is gradually heated at 18°C by the air exiting, which starts at 20° and is cooled down to 7°C. No external energy required, it’s a classic of neutral-passive buildings.
Yes, it is indeed amazing how fast CO2 levels can increase. This is especially a problem in low-ventilated classrooms.
At AirGradient we measure a lot of classrooms and it is not uncommon to see CO2 levels rising to above 4500ppm just within 2 or 3 hours. We wrote a blog post some time ago highlighting this [1].
Irony in the timing of your post as I too bought an air monitor filtering device a few weeks ago given my interest in measuring things I cannot see that may impact my families health. After several weeks of use and no ‘major’ concerns this past Saturday evening the air quality was hovering just below severe for many hours and the house felt 'stuffy' to me. I checked the devices readings and then asked each child and my SO independently how they felt after taking a deep breath and for generalization purposes they all stated 'stuffy' in a greatly shortened term. With a significant delta in temperature outside and in I too opened all the external doors and we had a slight wind that was then blowing through for about 5 minutes. Within seconds the air quality began to improve and after closing the house back up the air quality for the remainder of the weekend, and even now, has been optimal and everyone has felt much better. It is very interesting to measure something one can otherwise not see, such as one's air quality, and then take action to improve upon that thing which we never before quantified against how we felt which clearly has impacted our health in ways we may never know. Yet again, what you cannot see matters most!
I learned a lot about the ventilation situation at my place by tracking CO2 buildup. I now know that the time I should leave a window open to get CO2 levels indoors to approximate equalize to outdoor levels is 10x longer than what my intuition suggested.
I also discovered that every time I felt the air was “stuffy” and I needed some fresh air, it actually corresponded to a spike in VOx levels. When mom was visiting over summer, we discovered she is also sensitive to VOx levels.
This is my first winter with airthings wave. I’m curious to see how humidity levels are impacted by trying to keep my house warm.
Not GP, but I assume either is going to be noticeably worse than no fire at all, a closed log burner better than open. It's not going to stop me enjoying a fire though.
I think they're way under-appreciated, by my calculation they're almost at gas boiler prices in terms of £/kWh of effective heat (currently paying 6p/KWh of gas) - and perhaps particularly as someone living alone, 'spot heating' is great - so cosy by the fire in the evening, way hotter than I'd want to heat the whole house (room even) with gas. I just wish I had one in my bedroom (& perhaps bathroom) too, I wouldn't even need central heating (well, maybe I shouldn't be so confident before Jan...).
Yep. We have been wanting to get a fireplace insert which would be a major improvement in air quality, managing temperature, and how fast we burn through wood. The estimates we got were $2k for the insert and $2k to install. Still looking into it, but given the cost it’s not something we can move in immediately.
Commercial buildings have all sorts of rules under Ashrae in the US. Generally in commercial there is a minimum air exchange rate for occupied space. Pre covid it was being constricted for "green" energy initiatives in the name of energy and $$ savings. That restriction was allowed to be really clamped down on (more savings) if certain conditions were met like CO2 monitoring or people counters, both more tightly targeting how much fresh air people actually need and minimizing waste in conditioning outside air that isn't necessary. Post covid a lot of that got thrown out, commercial buildings are now generally over shooting OA exchange in the name of not turning these spaces into germ breeding grounds.
None of this really exists in the residential sector, but maybe it should. Homes in even the recent past are "leaky" enough to get enough outside air exchange for the low occupancy rates without actively conditioning and bringing in outside air. Some modern energy efficient homes that are wrapped and sealed extremely well might pose an issue to this.
By all means get a decent sensor that reads CO2, CO, PM1, PM2.5, and VOC. Radon if you are in a risk area. Your regular thermostat probably already gets you temp and humidity. It needs to have some way to do long term data logging, five or ten minute sample rate for a year for example. You really want to see how things are different across seasons.
With that data in hand there are plenty of things you can do if you need to introduce more OA to occupied spaces. Generally there are heat exchangers that can be dedicated to that sort of thing. Or a simple motorized damper opening up a small filtered OA duct on the intake side of the air handling unit. Ideally those devices would only be activated on unacceptably high bad air quality readings.
Amazing, I've never even heard of a ERU in residential work. I'm not an engineer so I'm unaware of the rules and regulations, I'm just pointing out what I've actually seen getting installed and what engineers sequences say about it.
I have an ERV in my house, running continuously. There are some great pieces of equipment out there, but they require conscious consumers and/or progressive code enforcement to end up in use.
I was blown away years ago, visiting the Anchor brewery in San Francisco. They approximated traditional steam beer in an enormous shallow pool. To improve consistency the whole room was at positive pressure, using state-of-the-art hospital air filtering.
Aside from the smell of beer, it was like stepping out into the Swiss Alps. I've never understood why rich people will spend $40K on audiophile equipment yet put up with crappy phones; I did a BBC interview remote in their NY studio using a $10K mic and the difference was staggering. Here, I swore if I ever got rich I'd want good indoor air.
It turns out I can afford to redo my house in California with a heat exchanger. I'm certain the hardest part will be finding a contractor who will exceed standards. Standards are why I have 1/2" pipes under my house. I want the bleeding edge of what's possible in my lifetime.
There is a massive difference in residential HVAC techs and commercial HVAC work. I had three bids from different contractors in my house and I specifically called out the whistling return vent, showed them how it sucks the filter in. The filter grill was clearly under sized for the CFM the AHU was pulling. Not one of them thought that was anything to be concerned about. None of them knew the first thing about manual D and calculating CFM for ductwork.
I can only recommend you do the homework and tell them exactly what you want installed. ie; be your own specification engineer. Anyone that's actually good at this sort of work goes commercial exclusively, that's where the money is.
Thanks! When we put in solar twenty years ago they kept patching me through to engineers they normally protect from customers, because I'd learned more than any customer-facing staff.
I was able to positive pressurize my apartment with an IQair during the ‘17-20 wildfires; it’s really worth it if you can figure out the intricacies and get it done.
Every single building is supposed to be positive with conditioned air at all times. Any building that's negative pulls in unconditioned air through all the cracks. Where I live it's very humid (think Houston TX) and if you pull that air in for a long time you end up with black mold inside the walls.
Might be by design. Plenty of buildings have a dedicated OA unit dumping into common areas and it gets pushed out to the private areas and individual rooms. Then gets pulled out via exhaust fans in rest rooms and other places.
I have been getting pretty high VOC readings in my bedroom on a uHoo, Airthings and now even the Dyson HP09 shows some lower levels. So now I am confident there is something being detected. Any advice on how to debug what is causing it and what VOCs it might actually be?
The weird thing is it seems to mostly spike at night time and even more so on the weekends.
I have a few hypothesis, such as:
- furniture offgassing
- us being in the bedroom
- gas cooking in the apartment building somehow settling into our ground floor apartment at night?
- it seems to be worse if we have the aircon on
- it really only seems to properly dissapate when the windows are open and theres good breeze and there seems to be a correlation between that and the sun coming up?
Like bisecting code, you can bisect airflow with plastic (e.g. 6 mil polyethylene) sheeting. Move the VOC sensor between isolated zones, or use multiple VOC sensor logs to track dispersal time/direction, narrowing down potential sources.
> it seems to be worse if we have the aircon on
Central or window aircon? You could place a VOC sensor near the HVAC duct input.
VOC? Deodorant, hairspray, perfume, cologne, scented soap, fabric softener. My VOC in the office spikes when I first get in from a couple of those items.
I was thinking about installing an air quality meter of some kind in my office because I suspect CO2 is high. Some of those other things (CO, PM1, etc...) may also be off.
If I install a meter and find CO2 is high, do the Ashrae guidelines give me any leverage against the building management?
Already it's often too hot because I'm on the top floor and I think they run the heat for the people on the bottom floor who are cold and the HVAC system doesn't seem to be able to deal with this.
There are guidelines in the spec but I think they are quite high. There's also studies that high CO2 kills concentration in schools, those seem more reasonable.
Zoned systems are supposed to be able to handle individual zone heating/cooling issues, floor to floor without question should be able to be controlled. Entirely depends on what is installed and how it is controlled. This is an area where cost cutting happens. Generally there's a ashrae spec saying there is a minimum of five degrees °F between heating and cooling.
So sure get a couple data loggers and report any findings to your manager.
> Post covid a lot of that got thrown out, commercial buildings are now generally over shooting OA exchange in the name of not turning these spaces into germ breeding grounds.
I think it has become clear that germ loads can be reduced significantly with filtering and ventilation.
Returning to college teaching mid-pandemic, I bought an SAF Aranet4 Home CO2 meter for measuring my classrooms. It mostly lives in my apartment, waiting to alert me in case I didn't realized I was using my gas range.
There's good evidence predating the pandemic that sufficient air exchange can nearly eliminate respiratory disease transmission. Just as they learned long ago in London that one could eliminate cholera by not drinking sewage water, we understand that the air quality and rate of exchange of indoor air should approximate that of outdoor air. We're however too cheap to do anything about this; it will take more deadly pandemics to drive the needed infrastructure changes.
Do you wince at the idea of people in London drinking sewage water? Those ignorant savages? Yeah, that's how people in the future will look back at us, getting colds and worse all the time in indoor air cesspools.
As we breath out CO2, it makes a great way to measure whether we're changing the air in a room fast enough to keep up with occupant breathing. Wilderness air passed 400ppm as part of global warming. My Manhattan apartment is above the Henry Hudson Parkway, and I can tell the time of day and day of week from the effect of traffic on my CO2 meter. I'm lucky to ever get below 450ppm.
The Aranet works far better than a $30 meter at the measurements a $30 meter will make, such as humidity. By appearance and build quality it's in a different league. CO2 is a bonus.
When I can, I run a pair of box fans exhausting through the windows in one room, letting the air in through the windows in the other room. This feels roughly like living on a houseboat, and is how I can read 450ppm.
I'm now at 728ppm after cooking lunch, windows closed. There's a good kitchen exhaust to a roof fan, so I can get that number down a fair ways by cracking a window.
Showering for fifteen minutes in my last apartment would push the bathroom CO2 up to 2000ppm, even with the stock weak exhaust fan on, and it would drop slowly for twelve to fifteen hours but never below 1200ppm so long as someone was home. 750 sounds like luxury :)
I live an hour drive north of New York City in a small, rural town of about 2,000 people. Large lot sizes, not much going on pollution wise. The lowest my CO2 has been so far is 659. This is when I open the windows for 30 minutes. I haven’t tried anything more aggressive than that. Either our rural, small-town air is worse than NYC for some reason, or the NYC air isn’t that bad? Very interesting.
Try opening your window for an entire day (e.g. when you're away) and see the result. If it's still above 600, my guess is that the sensor is crappy. Also, apparently some sensors recalibrate themselves against the lowest level they've seen in the past X days - so ventilating heavily may recalibrate it.
Yes, absolutely. Probably not popular with the HN crowd, but I use the "consumer-friendly" (cloud-connected) Awair for both CO2 and PM2.5.
And I've been absolutely gobsmacked to discover just how much my mental clarity and energy are linked to CO2 levels. Above 1200 I'm just kind of out of it -- I function but my thinking is like half-speed, 700-1200 is much better but still not optimal, whereas basically 600 and below I've got the energy to do anything. And I'm still "shocked" at how this is a recent discovery, and not common knowledge at all.
So now, I keep a single window open a crack all year round to keep levels below 600, and actually change how far it's open as needed depending on what the sensor says. On a room-temperature still day I might actually need it wide open because the air barely enters, while on a freezing windy winter day it only needs to be a couple millimeters open. Interestingly, my electric bill hasn't gone up by any obviously noticeable amount -- I think because so much of heating/cooling is "stored" in the walls/floor/furniture/etc., not just the air.
I haven't moved away from a gas stove because I rent instead of own, but it's shocking how quickly CO2 and PM2.5 rise, so I keep my vent hood blowing full blast while cooking, and also open multiple windows. I don't close the windows until both levels have returned to normal.
If that's regarding CO2, it "self-calibrates" weekly which means you need to expose it to "outdoor-quality" air once a week for it to know the CO2 "minimum floor". Which is annoying (my #1 wish for it would be manual calibration instead of auto weekly), but if you're leaving a window open a crack and your home is empty of people for several hours, that fixes it for me.
(Although you could have just gotten a defective unit too.)
I have several Airthings Wave connected devices, and I also purchased and installed a Panasonic ERV[0], which I have hooked into my HVAC system. Opening windows several times throughout the day was how I used to control the Co2, but in the winter and summer it became a huge hassle with the temp/humidity changes in the house, but with the ERV running 24/7 I will see an empty room drop to 400 ppm fairly quickly after people leave it (Airthings has an app). Generally rooms with people in them hover around 600-800 ppm with the ERV running. The ventilator will keep the humidity/temp levels pretty consistent because it has this cross capillary core that it runs the air through, but I do need a good few humidifiers running in the winter. The ERV also has the benefit of allowing you to control the air pressure in the house, which is useful for radon, as I was unable to get a good radon pump installed without destroying my downstairs (I live in a raised ranch where the "basement" is the first floor). With the positive pressure in my house + constant ventilation I never see the radon levels generally go above .5.
In my country it is common to start your day by opening all windows for 5-10 minutes. It’s done several times a day sometimes.
I worried about CO2 and general air quality in the office, particularly at those moments when coming back for lunch and noticing a “loaded environment” for lack or a better word. Not a problem anymore thanks to remote work :D
I feel like I'm very aware of bad air quality, especially in the office, where many people don't seem to care at all.
Definitely one of the biggest benefits from working at home for me, in the office I always felt exhausted after 1pm just because the air quality was so bad and airing was usually discouraged by angry looking coworkers ;)
Running an Awair in the kitchen while cooking is enlightening. I run the stove vent fan to mitigate.
There is no good solution for substantially mitigating CO2 in a living space other than ventilation. I also have an AlgenAir, and I love the business, but it can't on its own consume enough CO2 to compete with human production in a closed area. 100 devices- 2000+ plants equivalent- is what the CO2 absorption math says would be needed.
Since I couldn't find an affordable consumer device, I build one myself.
Levels in my living room never really exceed acceptable levels. My house is not airtight and constantly mechanically ventilated.
They have to pry my gas stove from my cold, dead hands. I refuse to accept indoor air quality deteriorates that much when using a proper hood (that means turning it on before igniting your stove).
I believe to remember I glanced over some of the articles mentioned and I seem to recall they were about poorly ventilated situations without proper hoods.
That doesn't say much about air quality WITH hoods in general, let alone my situation in particular. Incidentally I was already planning to build a little sensor array, specifically for the kitchen, that would would measure some of the nasty stuff.
But even if I would measure that stove is slowly killing me, I wont give it up. Just like I won't give up my coal fired barbecue.
With respect to a gas stove I've felt very similarly (and still have one), but after seeing a few induction cooktops and how nice they are I'll be looking at one for our next house.
Yeah, I used to prefer gas until we bought an all-electric house. The heating rate on the induction range that came with the house is bananas.
The burners go from 1-10 by halves and on 10 the big burner will boil a big-ass stockpot of water in what feels like a minute or two, and that's all I can use it for. 10 is literally too hot to sear meat, it will char it (and set off the smoke detector, apropos of the thread - it's a townhouse so of course the kitchen is right at the fucking center of mass of the house so the other rooms can have better light). It's also super-responsive and lets me get great heat control, if I go from 5.5 to 4 I can see what's happening in the pan change almost instantly. I never had a really fancy gas stove, but the ones I had were certainly not this responsive (although they sure beat the many crappy electric stoves I had).
It adjusts with buttons instead of a knob, which I kind of hate (a lot harder to work while cooking) but obviously that's not a comment on the heating technology.
The induction stoves I've had the "pleasure" of working with were all very efficient to get water boiling. For every other cooking technique they were terrible. Perhaps I had bad luck with the models I encountered. Maybe it was caused by the pans or maybe it is just getting used to it. But the fact they're almost exclusively controlled by buttons is absolutely a deal breaker for me. I can't handle the stress of 4 pans and pots with buttons not responding because of a smudge somewhere or just because f*k me. Not to mention the models that have 2 sets of controls for 4 burners, where you have to select the appropriate burner first. Those abominations have to be designed by someone who only boils eggs or cooks ramen or hates cooking in general.
We use the MZ, SCD as well as Senseair S8 and in my opinion all of them give a good enough accuracy. The build quality of the S8 and SCD is a lot better though. The most important thing is to stay away from eCO2 (estimated CO2) that some TVOC sensors offer which is very inaccurate.
I do. I just got started because it looked like a fun project to build, I went with the Airgradient DIY solution[0]. At first I used a combination of Prometheus and Grafana, then I integrated the solution with an MQTT server and Home Assistant[1] instead.
I live in a duplex, which means there's _a lot_ of air volume and mostly just me, so CO2 levels don't skyrocket and won't even reach 1000ppm after the whole day. I usually blast the windows open for a few minutes first thing in the morning and that does the trick, bringing levels down to ~500ppm.
What's worth mentioning is the massive temperature difference in between the top and the bottom floor, which is from 3 to 5 degrees Celsius higher upstairs. CO2 is also higher upstairs, about 150ppm, and P2.5 is usually higher downstairs (do they fall to the ground?)
I'm taking one of the sensors to my parent's this week, since they use a closed log burner to heat the house and I'm curious what the levels are going to be.
Last anecdotal point, I was fitting a Bosch Athlete upright vacuum cleaner with new VTC6 batteries for extended battery life and increased suction power this weekend, which requires a lot of soldering iron and tin, and I was amazed at how the PM2.5 would go crypto-style _to the Moon_
I stopped using my gas stove about 3 years ago, after it seemed to be causing histamine problems. It was only later that read that this was a known problem, rather than only a bizarre correlation I noticed. I now use an electric air fryer toaster oven, which causes only small particle increases.
I recently got a semi-credible-looking non-IoT air quality monitor (CO2, TVOC, PM1, PM2.5, temp, humidity). I can't say how good the self-calibration is, but when the readings vary up/down usually seems to make a lot of sense.
For CO2 (and other air quality concerns in this problematic old student apartment, in a crazy university neighborhood housing market), I almost always have a couple windows cracked open.
And, if I haven't had a central window open wide for awhile, I'll try a large air exchange with outside, by opening many windows wide for a few minutes.
> after it seemed to be causing histamine problems
Interesting. My wife and I both realized over the pandemic that we are histamine sensitive (her much moreso than me). We have had the symptoms most of our lives but I do wonder is gas stoves make it worse. We stay in places with gas stoves sometimes, often with poor ventilation in the kitchen. I will have to see if there is any correlation of the severity of our symptoms.
I've had similar issues, but since I also experienced it near electric stoves it wouldn't be caused by the burning of gas.
I've hypothesized it is caused by overheating cooking oil.
Before induction cooking, gas stoves generally used to be able to provide more heat than electric ones. So its easier to cook hotter and burn more oil with those stoves.
FWIW, I was seeing it only with boiling pasta and vegetables in stainless pot on a newish gas stove. (Sometimes draining and then heating with olive oil in it, but on a lower temp.)
We picked up the Aranet 4. Things were fine until we replaced our windows with fancy new ones. Our air quality plummeted, CO2 > 2200.
We got a new air exchanger installed, connected to our existing forced air hvac system. It runs at a low speed 24x7, which keeps things at a reasonable level.
It has a few settings like: continuous, 20 minutes/hour, 40 minutes/hour, and "humidity control". Nothing for CO2 control though. I have aspirations to hack the control module and make it care about CO2, but I've also got two kids and a startup so who knows how long that will spend in the backlog.
I used to monitor CO2 in the house with Awair units, specifically those because it allegedly interacted with my Ecobee AC control. So I could say if the levels were rising, force the fan on to push fresh air around, although I'm not sure I ever got it working correctly.
It's a big problem for me, as living in Florida basically means the AC runs almost year round. In the colder months we open the windows as much as we can to let the levels drop, but from spring through autumn it's just too hot to keep them open, as it just pushes the AC harder to cool more and more, while also increasing the humidity.
We definitely started getting better nights sleep once we had either the windows open, or the door to the bedroom open. I also rarely shut the door to my office as I was getting so sleepy at my desk during the afternoons.
I have no real solution for the hot months anymore, as Awair has basically abandoned the units I was using. I've just had some Zigbee air quality monitors arrive that I ordered on Aliexpress, but I'm skeptical at how accurate they'll be. Infact I'm skeptical at how accurate any of them are after I did some research into building my own and adding some sensors to an ESP32.
Going to have to try and come up with some HomeAssistant automation task with the Zigbee sensors and Ecobee to push fresh air through the house.
I did that in the last weeks. I live in Germany and we have a flat that is not very modern but has reasonable insulation. What I learned that under these conditions, with two people in a 30 square meters room, CO2 rises so quickly that one has to do intermittent, full ventilation (about 3 to 5 minutes, in Germany it's called "Stosslüften") for about every hour, to keep CO2 levels below 1500 ppm.
During the night in a smaller room, one can get easily levels of 3000 ppm. That's not dangerous, but it is not recommended for places where people have to work in a concentrated manner, like offices, or schools, for example. The recommended limit by the federal office for environment is 1000 ppm.
And that build-up of the stuff is a big difference to where we were living before (Edinburgh) where that kind of ventilation was basically unnecessary because no window closed that hermetical (well we lived in one of those wonderful 140 year-old houses in New Town).
In the end, with good insulation, it becomes increasingly important to have some active ventilation - it is also more economical, because it saves on heating. And that is in fact becoming more widespread with new family houses.
I use an Aranet4 in the living room. Mechanical ventilation in most homes in NL allows configuring a precise flow rate in cubic meters so I've found the breakpoint to keep it < 1000 ppm.
I took it to the office one day and it measured 2000 ppm. It turned out one of the motors that brings in fresh air in the ventilation system had failed, I wonder if it would have been noticed without the meter. It's a great little device.
I have a Nentatmo CO2 monitor in my apartment. I discovered that during training on a stationary bike, the CO2-levels exceed 1000ppm. Probably due to increased breathing. Therefore I increase the ventilation when I do a workout
I'm using a relatively cheap (68EUR) TFA Dostmann AirControl Mini CO2 Meter (also available from different brands as well) based on ZyAura platform. I soldered a connector to connect it to an ESP8266 board flashed with ESPHome software [1] and then send measurements to the Home Assistant instance.
This system works well, the sensor is on my desk, the CO2 drops quickly below 600 ppm when the window is open, but then immediately returns to above 800 ppm shortly after the window is closed. For example, I currently have 982 ppm.
At night, with 2 people sleeping in the room, the level often rises to 2500 ppm. So even though I ventilate the house much more often than I did before I bought the sensor, it's still not enough to maintain healthy CO2 levels, and with the current energy prices and cold weather, I don't know what else I can do, I have no space to install heat recovery ventilation.
That's the same brand I bought, after the last similar thread on HN which led me to get interested in this topic.
I had never monitored CO2 at home, and now I see that it routinely goes beyond 1500 in the living room. I can open windows and in 5 minutes it goes down to 700-800... together with all the warm air that was costly to produce now that's winter and it's so cold outside. And in 1 hour it goes back to 1000+.
So I've ended up getting used to see and ignore its metrics, because the alternative is to open windows every 60 minutes and lose a lot of money on heating.
Modern homes are so well insulated that it sometimes happens that a family will host a big holiday party, use their fireplace for the first time, and then get dinner started shortly thereafter; the first time their nearly commercial grade overhead hood fires up, hot embers will be blown across the floor of the room with the fireplace.
(Or, those homes correctly have a "make up air" duct installed, which resolves this scenario)
We recently rebuilt the wall that houses our hood for our propane kitchen range. It's 4 inches, and I asked how difficult it would be to move to a 6 inch duct, since it's far more volume of air to be moved. Of course, the answer was a logistical difficulty and out of budget.
On particularly damp days in the winter here in New Hampshire, if someone accidentally leaves a bathroom fan running, and perhaps the kitchen hood, it can be nearly impossible to get a wood stove fire going. So although these electrical systems are not drawing what seems like a lot of air, they have practical effects on unrelated systems.
Interesting this tracks in homes too but makes sense I guess. In restaurants the hood exhaust/ventilation system is one of if not the largest one-time cost. It's why restaurants almost always move into spaces previously occupied by restaurants, the cost to add it is usually just too much except as part of new development.
We provide a commercial and a popular open-hardware air quality monitor [1] that includes CO2 as well as PM 2.5, VOCs, NOx, humidity and temperature. I am talking everyday with people around the world about why they want to measure air quality and the parameters they are interested in.
On CO2, we observe mostly three different use cases:
CO2 as an approximator of Covid infection risks: With the possibility to use CO2 levels as an aproximator of aersols with potential virus load, CO2 became quite popular as a measure about how effective the ventilation works.
CO2 as an indicator of cognitive performance: There are a number of studies, e.g. [2] showing a clear link between high CO2 levels and impaired cognitive performance. I am seeing more and more people that especially want to measure CO2 levels in order to keep them low and have a better working environment.
CO2 as an indicator of ventilation rates: Without ventilation, indoor pollutants e.g. harmful gases from furniture, colors, building materials etc. will increase. Some of them can be measured as TVOCs but not all of them. Low CO2 values indicate a high rate of air exchanges and these typically flush out these indoor pollutants. Ideally the HVAC system uses HEPA and carbon filter for the fresh air intake to ensure that the air coming in is clean. In climate zones with a high differential between indoor and outdoor temperature, heat exchangers should then be used.
If you measure more than CO2, but also PM and Temperature and you have the ability to control your ventilation rates (either by manually opening windows or by a demand controlled HVAC system) you can see and optimize potential tradeoffs, e.g. cooling or heating energy is wasted by increasing fresh air ventilation rates or opening windows will bring down CO2 but increase PM if you live in a polluted area.
Regarding the OPs question on moving away from gas stores. Here the new TVOC sensor from Sensirion SGP41 [3], that can be uses in our open-source open-hardware air quality monitor [1], is able to measure NOx and can be a good indicator if your stove emits fumes into the living area.
I don’t measure or actively mitigate carbon dioxide; however, we do run particulate filters 24/7. No central air, but we use a large window fan to pull fresh air into the house during the summer months.
Winter is the real concern. Not much opportunity to air out the house when the temp is consistently below 20 degrees Fahrenheit.
> "I don’t measure or actively mitigate carbon dioxide; however, we do run particulate filters 24/7."
this is the right order of concern. pollution (particulate matter) is much more damaging to our tissues than CO₂, which is basically inert in comparison (e.g., people die of smoking, not working in a stuffy office). life evolved alongside CO₂, but not so much alongside NOₓ, SOₓ, CFC/HFCs, dioxins, and the like. but in every thread about air quality, the majority of the discussion is on CO₂. the mediopolitical narrative is driving hard in this direction, to our detriment, as plainly evident here.
We borrowed a sensor for a few weeks and measured different rooms. The readings are especially high when we invite people. (We cook electric , and I think the stove has little to do with high CO2 in a living space.)
The conclusion is that we need to ventilate more. Especially in the bedroom. Sometimes it’s hard to find a good balance between ventilation and heating.
I should add: it was rather fancy as it could display graphs and such. But in the end that not very useful, after a few days of watching the readings you start to understand when CO2 increases (people) and decreases (ventilation). It never reached unhealthy levels of CO2 in our home.
Yes, but I mostly did it like some others around the start of the pandemic due to all the time everyone was spending indoors and I wound up getting a few devices from Awair. After doing this for a couple of years now, at least in my home, CO2 really never rises to the level that it's a concern. This is largely because my HVAC system is configured to circulate the air in my home every 30 minutes regardless of heating or cooling. With this feature off, yes, CO2 does eventually build up to unhealthy levels rather easily in rooms that have doors closed and related. Ultimately, this experiment gave me a greater appreciation for my HVAC system. On a side note, monitoring rising CO2 levels can, well, be used as a detection method to determine whether someone is in a room and for how long they've been there.
A related question: does anyone have a CO2 detector in their vehicle?
I keep wondering if CO2 is the reason that so many cars try to force recirculation off. I am super sensitive to exhaust fumes so I am constantly turning it back on.
I am the same as you, so I took my Senseair S8 for a ride once. It takes almost no time for two people to push it to 2000 ppm (which is where its accuracy starts to go out of whack), and maybe half an hour to 10000 ppm (which is the absolute upper level it can measure, so the real level may be even higher).
I've used a cheap car though, and it shuts off recirculation using a timer. Maybe it's different in more advanced models.
The sensor may be inaccurate, although it's one of the better ones if you're not willing to pay hundreds of dollars. After living for many years at similar levels of CO₂, I don't really feel them at all, so it's hard to (dis-)confirm these findings.
Also need to weigh the long-term effects of CO2 vs other acute risks like fire. It's been a minute since I took the course on this but iirc smoke inhalation is one of the bigger dangers of home fires and having bedroom doors closed is the strongest mitigator of it (other than smoke detectors obv.)
I really don't have the information to weigh this either way but I've considered closed doors a safety measure for years so this throws me off in an unsettling way.
I retrovitted the bedrooms (and living room) in my house with a demand controlled fresh air system that contains high quality HEPA and carbon filters. The difference is extremely noticable. Especially when the air quality outside is not good, you feel like you are on a mountain top with crisp, clean air.
Yes, I got a meter that shows the number and beeps when it hits 1000 ppm, which it does sometimes in my office after a few hours with the windows closed. A good investment in productivity.
I have a ZyAura sensor connected to Home Assistant with ESPHome [1]
I've found that I need to keep my bedroom door open at night, to keep Co2 levels below 1000 PPM. Also, I need to increase my apartment's ventilation by one or two levels for board game nights (or whenever there are 4+ people present).
I only have a TFA Dostmann CO2 monitor. It doesn't have any data connection capabilities, you just read numbers from the display. And it needs usb power, doesn't have batteries. Maybe I should buy an Aranet4.
I used to do it by using an Awair device, I could feed it into HomeKit which is why I choose it in the first place. Then some weird crypto thing (planetwatch.io) happend which made them really expensive and I sold it for a lot more than I bought it.
Since then, I don't monitor any more and I don't miss it as I'm always airing the room multiple times per day anyway and I didn't really get something out of it except some pretty graphs.
There's not much else you can do. Even in the winter, I open it long enough to change the air and hopefully without letting the heat escape too much.
I used the old generation Awair, they are no longer supported. Now it reads false readings about air quality, so I'll be switching to one of the competitors. Good things is that Awair seem to have opened the door, there was not a lot of devices a few years ago and now there are a more options.
I use an Airthings device to measure the air quality in my bedroom. I'm noticeably more groggy in the morning if there is more than recommended CO2 in the room. I don't care that much about the other things it measures. Another nice feature is having all of the history on my phone.
CO2 doesn't matter because it is unlikely to exceed 1000-1400 ppm. Feel free to measure it but it will be insignificant. As soon as a door is opened, levels return to atmospheric range.
It's CO that's an issue, and related to incomplete combustion.
I use an BlueAir 680i, so indoor air is cleaner than outdoor.
Well, 1000-1400 ppm is my typical level in the room 5 hours after the last airing. Just before morning in the bedroom it can go up to 2500 with all the interior doors open.
Yes. From the monitor I discovered that co2 in my home office rises from around 700ppm to 1200ppm in just a few hours unless I open a window or the door. Now I generally leave the window a little open or if the neighbours have their fire down I just open the door to the hall.
I've found that just having a tilted window is enough to make a difference. Then it's always <800ppm. I do monitor C02 levels in the office, and noticed that I never check the value if it's <600ppm, and that anything >800ppm makes me unproductive.
Not scientifically. We try to leave the windows open as much as we can, weather permitting. For even more outside air flow, we installed a screen door on our front door. Total cost was about $150 USD.
When we run the gas stove, I try to run the exhaust fan.
Anyone has a recommendation for a portable heat exchanger/heat pump for locations where no permanent modifications can take place and no window units are allowed? Preferably with a working range of -30c and +50c.
How many people do you need in an apartment for CO2 to become a problem? AFAIK some carbon dioxide is even necessary for oxygen to be utilized in your body and for parasympathetic nervous system to work.
I’m surprised how many people aren’t sensitive to lack of fresh air. I yawn, get dehydrated, and generally just feel off. I’ve stayed in hotel rooms with no opening windows and barely got an hour’s sleep.
If you have a properly sized range hood, won’t that pull out the CO2? Maybe you just need to leave it running longer? I could see a CO2 meter helping with this.
Well, the hood on its own will be pushing air out and if system is constructed correctly it would push some air in but people generally turn it on only when there is smoke, not for stuff like "just" boiling something
And even if it is on, the CO2 at least initially won't be super hot and instantly go up; as flame hits the cookware it will cool down to the temperature of it
Turning my hood on full blast every time I use the burner has become a habit for me. I also luckily have my hood attached to an external wall which is directly blowing outside, which I know many don't.
And from studies I read the issue with gas stoves are pretty much exclusive to developing countries with bad stove standards and poorly ventilated kitchens.
there is a ton of devices that do that on amazon. here ( Brazil/beach ) i get only 300-400 ppm, ps: i dont use gas to Cook/shower. everything is elétric
I have learned a lot while using it for a couple weeks. First, making a fire in your fireplace is great for ambiance but drags air quality down substantially. It eats up oxygen a lot and make the CO2 increase sharply. It also causes very high spikes in particulate matter (both 1.0 and 2.5 micron) from putting the burned byproducts into the air.
I also started improving the energy efficiency of our heating system by fixing spots in the house where cold air comes in. While this results in less energy used to heat the home, it causes CO2 to increase because there isn’t anymore large holes to bring fresh air in. This device helped me learn that CO2 is and energy efficiency are circular problems. The tighter my house is, the more I need to focus on ventilation - exhaust out and fresh air in. It sounds complicated but for me it just means opening windows throughout the house for about 15-30 minutes per day. That alone makes a major difference on everything - Radon, PM 2.5, PM 1.0, CO2, etc.
Lastly just want to mention that it’s amazing to me how fast CO2 levels can rise with just my husband and I in our living room watching a movie. Good ventilation is something I definitely recommend everyone start measuring and working on.