Also - has anyone moved away from gas stove since recent articles about the issues with fumes they emit into spaces?
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.
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.
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.
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.
[0]: https://na.panasonic.com/us/home-and-building-solutions/vent...
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
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).
The SCD30 generally seems to report higher CO2 levels than the MZ-14A. I believe it is probably more accurate because of it's calibration technique.
Both are NDIR based sensors.
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_
[0] https://www.airgradient.com/open-airgradient/instructions/di...
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.
No.
> mitigate CO2 in your living space?
I open the window occasionally and when they are not open the are pretty draughty windows.
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.
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.
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.
(Chiming in to diminish sample bias.)
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.
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.
(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.
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.
[1] https://www.airgradient.com/open-airgradient/kits/
I use its API to connect to it once a day and download the last 24hrs of logs (it stores 14 days worth on the device).
It's expensive - but it's really the best there is IMO.
I try to open a window on either side of the house when the co2 gets over about 750~
Winter is the real concern. Not much opportunity to air out the house when the temp is consistently below 20 degrees Fahrenheit.
I supposed I should look into a heat exchanger.
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 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.
Determined my kids rooms are big culprit with doors closed. (Up to 1400 at night) now keeping door open.
I doubt this will fly when they are older so looking into installing an ERV/HRV system if anyone has any recommendations.
it's just missing the airgradient https://www.airgradient.com/open-airgradient/kits/
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).
https://www.amazon.de/-/en/Dostmann-31-5009-AIRCO2NTROL-Moni...
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.
It's CO that's an issue, and related to incomplete combustion.
I use an BlueAir 680i, so indoor air is cleaner than outdoor.
During winter nights we routinely hit 3k-4k in the bedroom by the morning. During summer it never went over 900 due to open window.
Solution, get up in the middle of night to open balcony for a few minutes, drops to under 1k very quickly.
When we run the gas stove, I try to run the exhaust fan.
Mitigation - one of my bedroom windows is rather leaky & I've decided to leave it as is due to co2 concerns.
That was enough to lower CO2 levels to the bottom of the sensor's sensing range.
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.
We use electric stoves, but would prefer gas.