[HN Gopher] Monitoring my home's air quality with AirGradient's ...
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Monitoring my home's air quality with AirGradient's DIY sensor
Author : geerlingguy
Score : 342 points
Date : 2021-09-08 14:02 UTC (8 hours ago)
(HTM) web link (www.jeffgeerling.com)
(TXT) w3m dump (www.jeffgeerling.com)
| falconblock5 wrote:
| Could anyone advise of the best way of getting hold of the PCB?
| Looking at the air gradient webside they provide "Gerber files",
| do these need to be sent to a PCB manufacturer to create? If so,
| does anyone have recommendations of which to use? It is something
| I would like to learn about but I am rather new to.
| roflchoppa wrote:
| I ordered like 5 of them the other day from JLCPCB it was like
| 6 bucks shipped to my place.
|
| I saw this post online, I've had the pm2.5 sensor sitting
| around for a long time...
|
| https://benjamincongdon.me/blog/2021/08/08/DIY-Air-Quality-S...
| secabeen wrote:
| I built one using these instructions and a ESP8266:
| https://www.pieterbrinkman.com/2021/02/03/build-a-cheap-air-...
|
| It publishes its data via MQTT, and you can use any system that
| can subscribe to a MQTT queue to process, display, etc. it.
| adamjb wrote:
| The last time AirGradient popped up on HN, the guy who runs it
| said if you get in contact and ask nicely they might have a
| spare one to send you.
| tnorthcutt wrote:
| Link: https://news.ycombinator.com/item?id=27125763
| turbocon wrote:
| oshpark is what we used in college https://oshpark.com/
|
| $5/sq inch and you get 3 copies of your board
| Afrodev wrote:
| https://oshpark.com/shared_projects/M6wg5Xzs Actions > Order
| Board
| numpad0 wrote:
| KiCad for design and JLCPCB or FusionPCB for manufacturing has
| been good enough for me to go from nothing to a completed
| board. Yes, gerber files are equivalent of "compiled binary"
| that you send to a PCB manufacturer to be printed.
| simcop2387 wrote:
| I've had good experience with jlbpcb in the past, they usually
| have some deals going around on youtube electronics channels
| too.
| Animux wrote:
| There is a version from superhouse.tv with the same pms5003
| sensor: https://www.superhouse.tv/39-diy-air-quality-sensor-
| part-2-d...
| danans wrote:
| > But after a few weeks, and after adding in a manual temperature
| adjustment to compensate for that sensor's inaccuracy, the
| AirGradient has been a very stable and helpful addition to my
| home environment monitoring.
|
| When you are DIYing this sort of thing, I would think you would
| need to make at least a couple of them to see if they calibrate
| to the same measurement, assuming what you are after is greater
| precision and control (why else would you DIY it?). Even then,
| both devices could calibrate to the same very imprecise value.
|
| To really validate this, you would need to put it in an
| controlled environment with known air pollution levels. Just
| placing it outdoors when the weather report says 200AQI wouldn't
| work since that's an average over a large area, not a point
| measurement.
|
| I imagine the sensor manufacturers have done some calibration -
| the article mentions a self calibration period for some, but once
| everything is in the final package, I'd expect the behavior to
| change.
| asdff wrote:
| With this data it seems like you'd be more concerned with the
| relative value and its change over time anyhow rather than the
| true value.
| geerlingguy wrote:
| I have two identical boards now, along with my TemTop portable
| unit, and the CO2 is quite close (< 1% difference usually), and
| PM2.5 readings are more like 5-10% different. The temperature
| is the biggest outlier, but I need to figure out a better
| placement for the temperature sensor to get that issue fixed.
| ashtonkem wrote:
| Most of the DIY solutions I've seen use pre-packaged PM
| sensors, which are probably the same parts embedded in over the
| counter solutions.
| danans wrote:
| Yes, but has the final assembly been calibrated against a
| known controlled environment?
|
| Without that, the readings from the device become more of a
| crapshoot, which is fine if there is no desire for greater
| precision (i.e a just for fun project)
|
| Sensor manufacturers cannot calibrate for every possible
| packaging configuration.
|
| As someone who has DIYed a lot of stuff related to indoor
| climate, I tend to save my effort for the mitigation work,
| and use well tested measurement tools to validate those. This
| is for the same reason that one doesn't usually DIY a
| multimeter before doing electrical work.
| jiveturkey wrote:
| yup. not entirely useless, but especially for the borderline
| yellow/orange AQI you want to know the error.
|
| http://www.aqmd.gov/aq-spec tests and compares commercial AQM
| vs lab grade instruments. It isn't quite enough to compare a
| commercial unit with the same sensor, because you don't really
| know the mfr calibration (if any), but this will get you a much
| better idea of performance.
|
| i personally prefer to have a commercial sensor that has an
| API, rather than DIY.
| Johnny555 wrote:
| Does anyone have any plans for a cheap DIY Ozone sensor? My house
| came with an electronic air cleaner called an iWave:
|
| https://iwaveair.com/
|
| It claims to not emit any Ozone, but I'd like to be able to
| meaure it, and the commercial sensors tend to be expensive.
| dperfect wrote:
| Not sure if this is DIY enough for you, but I'm using an MQ131
| (about $20-$30 on Amazon, probably cheaper directly from China
| [1]) in an air quality monitor I'm building. There's an Arduino
| library for it [2], and from what I can tell so far, it does
| work, though it's probably not super accurate. It's also
| somewhat sensitive to environmental factors, but you can
| correct for some of that with known temperature/humidity.
|
| [1] There are a few different kinds of MQ131 (for high and low
| concentrations); you'll probably want the low concentration
| one. I also removed the bare sensor from a breakout board I
| purchased so I could access it directly from my custom PCB.
|
| [2] https://github.com/ostaquet/Arduino-MQ131-driver
| Johnny555 wrote:
| That's exactly what I'm looking for, looks like I can get a
| $30 MQ131 with detection a range of 10PPB-2PPM [1], and a
| "Good" indoor level is 0 - 54ppb [2]. It doesn't need to be
| super accurate for my use case, basically I just want to turn
| on the electronic filter and see if there are any detectable
| levels of Ozone.
|
| [1] https://www.sainsmart.com/products/mq-131-gas-sensor-
| ozone-m...
|
| [2] https://learn.kaiterra.com/en/resources/ozone-what-
| levels-ar...
| clipradiowallet wrote:
| This doesn't answer your question - but in all seriousness you
| can smell it. Even the smallest amount of ozone has a _very_
| distinct smell you will recognize. If you stand in front of
| your air sanitizer and let the air pass over your face, you
| should be able to smell the ozone immediately.
|
| If you haven't smelled it before - I would recommend going to a
| retail store that sells ozone-based air sanitizers. That should
| give you a whiff of the stuff for reference. You can also find
| it in [some] hospitals for air sanitization. I imagine once you
| smell it, you will realize you have smelled it before and maybe
| not realized it was ozone that you were smelling.
| s0rce wrote:
| the word ozone actually comes from the Greek word for smell
| (at least according to wikipedia, I don't speak Greek.)
| Johnny555 wrote:
| I know what Ozone smells like (I remember the old laser
| printers that were also effective ozone emitters), but trust
| a sensor more than my ability to smell low levels of Ozone.
|
| My air purifier is built into the furnace ductwork so it's
| already pretty diluted air by the time it comes out of a
| duct.
| clipradiowallet wrote:
| > My air purifier is built into the furnace ductwork
|
| That's neat! Do you know if the ozone is produced before or
| after it reaches the blowing mechanism? I ask because if it
| is produced _before_ , like right after the air intake,
| that's a really great setup for keeping your ductwork mold
| and mildew free. I've wanted to buy such a system but keep
| holding out for things to get cheaper... in the meantime, I
| use an ecoquest "FreshAir" model sitting on top of the
| fridge.
| Johnny555 wrote:
| Well I don't know that it creates ozone at all, the
| product claims that it creates purifying "ions", but no
| ozone. And I don't _want_ ozone.
|
| The unit is installed after the filter, but before the
| air is sucked into the blower.
| alexfromapex wrote:
| Why is this person's house 82 degrees?
| reaperducer wrote:
| _Why is this person's house 82 degrees?_
|
| When I lived in the desert, 82deg was comfortable for me.
| Generally, the humidity was below 10% (NWS reading, as most
| cheap consumer sensors are not precise below 10%). But even in
| monsoon season, when the humidity would spike, it was still
| fine.
|
| I guess you get used to it. My wife never did, so when she came
| home from work she'd turn the temperature down to 78deg.
| dexwiz wrote:
| At 42% humidity, I'm guessing they live in a subtropical
| climate. Florida's?
| LeifCarrotson wrote:
| No, St Louis:
|
| https://www.weather.gov/lsx/monthTab
|
| It was in the upper 80s/lower 90s throughout July and August,
| when this data was likely collected. And relative humidity
| hit 80-90% every morning, averaging about 65% as it warmed
| up. It's sticky in summer. I live in Michigan, and even with
| a cool breeze from our magnificent freshwater lake, half an
| hour inland it's similarly hot and humid. I kept our house at
| 78 when we're home, 82 when it's just the dog, and 76 when
| company comes over. I think the air conditioner keeps
| humidity in the 40% range, though I'm reading this article
| because I lack a hygrometer/air quality sensor and don't
| really have hard numbers for that, only that humidity is
| significantly less indoors than out.
|
| Also, he mentions that the orientation of the case causes
| convection off the ESP8266 to increase the air temperature by
| a couple degrees (Farenheit).
|
| If you're one of the Silicon Valley HN readers looking to
| move to the wide open spaces and relaxed culture of the
| Midwest, do be aware that climate is a big deal; coastal
| California's perpetual mild climate is an aberration.
| zeku wrote:
| In Tennessee myself and it is only just now getting to a
| temperature/humidity that is bearable to be outdoors.
|
| March spring hits and the pollen is crazy until June and by
| then it's too hot to really be outside without tree cover
| from 9am-8pm until around now.
|
| My area is one of the worst pollen places in the country.
| You owe it to yourself before moving to look at a pollen
| map as well.
| dexwiz wrote:
| As a Midwest native, but SF resident, I don't think I could
| ever move back due to the weather.
| DiabloD3 wrote:
| Maine is relatively dry. My house generally stays around
| 40-60% humidity year round except during the coldest parts of
| the winter, independent of the outdoors in both extremes.
| bombela wrote:
| 82degF == 27.7degC
|
| https://en.m.wikipedia.org/wiki/Fahrenheit
| zekrioca wrote:
| Why not?
| mikodin wrote:
| > The case is well-ventilated, and my only complaint is the
| natural convection causes very-slightly-warmed air from the
| WeMos D1 and CO2 sensor to pass over the temperature and
| humidity sensor on the top, meaning those readings are always a
| bit higher than ambient--at least in my office.
|
| Likely because of this.
| geerlingguy wrote:
| Heh, this. I keep the thermostat between 78-80degF during the
| summer months (which allows the A/C to run enough to keep
| humidity down below 50%), and between 68-72degF in the
| winter.
| [deleted]
| asciimov wrote:
| Here in South Texas I keep my house at 78deg during the daytime
| in A/C season (that's typically March-November, plus some days
| the other months). If the ceiling fan's aren't on, and the air
| isn't moving around properly, it can easily get up to 82deg.
| It's perfectly comfortable. (You acclimate to it)
|
| Understand, the average high is in the mid to upper 90's and
| trying to get a home a/c to cover a 20+ temperature difference
| is difficult and significantly drives up the monthly power
| bill.
| [deleted]
| post_break wrote:
| I wish there was a cheaper buy it option. I really really want to
| do this but I'm worried I'll get half way and get stuck.
| dhritzkiv wrote:
| I'm the same.
|
| Plus, my living in Canada means getting all the different
| components piecemeal, often from different suppliers/sellers is
| a giant PITA. This is further complicated by my self-imposed
| restriction to not buy from Amazon. And this is before the
| headache of shipping costs (often $15 as the lowest option,
| even for small parts)
|
| I'd love a ~$200-300CAD pre-assembled or kit option where I can
| own the data, access it in a standard fashion, and optionally
| choose to crowd-source it.
| tzs wrote:
| The WeMos D1 Mini link ends up at an AliExpress login page, not
| the product page for the D1 Mini. It looks like you linked to
| your order page instead.
| geerlingguy wrote:
| Sorry about that! This is the one I bought:
| https://www.aliexpress.com/item/32651747570.html?spm=a2g0s.9...
|
| I've also updated the link on my site.
| fuzzybassoon wrote:
| Not the author, but this[1] looks to be the listing for the D1
| Mini from the LOLIN official store.
|
| 1:
| https://www.aliexpress.com/item/32529101036.html?spm=a2g0o.s...
| avodonosov wrote:
| Anyone can recommend good quality inexpensive sensors?
| harias wrote:
| Try the one's listed here maybe:
| https://newscenter.lbl.gov/2020/08/18/low-cost-home-air-qual...
| asdff wrote:
| Not exactly inexpensive. These are "low cost" in that they
| don't cost $20,000 like the sensors used by government
| agencies, but they aren't what I as a consumer think low cost
| means.
| numpad0 wrote:
| I can recommend against one type of bad sensors. VOC sensors
| paired with a temperature sensor that can generate "eCO2" value
| is known bad, such as CCS811/BME280 combo board.
|
| Those sensors guesstimate CO2 concentration from air
| temperature and changes in ambient alcohol/acetone/hydrocarbon
| levels, which drifts into positive infinity and is simply do
| not correlate well with actual CO2 level.
|
| Those sensors are dirt cheap, and can still be used as a rule
| of thumb to encourage regular ventilation, but are nothing more
| than that. If you want to actually see CO2 levels, avoid those.
| Someone1234 wrote:
| I was surprised to learn that the Airthings Wave Plus ($180~)
| doesn't measure PM2.5. It is cool that it does Radon and VOCs
| which this cannot do.
|
| This seems like it could either compete OR complement an
| Airthings Wave Plus for like 35% of the cost. Since they both
| offer different and overlapping data.
|
| I wonder what you'd need to do to get Radon and VOCs too in this
| solution (essentially match and exceed the Airthings Wave Plus)?
| at_a_remove wrote:
| Honestly, it seems like there's a long list of things to
| monitor:
|
| * Radon * Carbon dioxide * Carbon monoxide * Nitrogen Dioxide *
| Sulfur Dioxide * Ozone * PM2.5, PM10 (any others?) * VOCs *
| Temperature * Humidity * Pressure
|
| It is an opportunity for someone to make a "suite" sensor so
| you could scatter them around the house for good average
| measurements.
| endymi0n wrote:
| The air-q pro comes pretty close (I'm thinking of buying it),
| but it's rather expensive and I haven't seen any reviews yet:
| https://shop.air-q.com/air-Q-Pro-air-analyser-14-sensors
| 5e92cb50239222b wrote:
| Last time I looked into gas sensors (for measuring SO2 and
| NO2 which reach extreme levels in my area), they were $100+
| each, depending on the gas it's measuring.
| at_a_remove wrote:
| I think that kind of thing could get knocked down in price
| a bit with scale and inclusion in a sensor suite.
| roessland wrote:
| Have you looked at the View Plus (EUR300-ish)? It has PM2.5,
| CO2, radon, humidity, pressure and temperature. Also I believe
| it has multiple of some of the same sensors for better
| accuracy.
|
| Way overpriced vs AliExpress but oh well.
|
| https://www.airthings.com/en/view-plus
| abledon wrote:
| This thing looks amazing, and entire first batch is sold out!
|
| Definitely going to pick one up when they are available. I
| might save a few bucks diong the DIY route, but at the end of
| the day, I would just buy 3-4 more shares of a vanguard
| thing, and have to tinker/maintain a grafana dashboard, where
| this thing is probably getting new apps/updates/features
| monthly.
| robbomacrae wrote:
| "The case is well-ventilated, and my only complaint is the
| natural convection causes very-slightly-warmed air from the WeMos
| D1 and CO2 sensor to pass over the temperature and humidity
| sensor on the top, meaning those readings are always a bit higher
| than ambient--at least in my office."
|
| Have you considered turning it around?
| geerlingguy wrote:
| But then the display would not be oriented correctly ;)
|
| What I'm planning on doing is soldering a jumper to the board
| and having the temperature sensor hang out the side of the case
| a bit, towards the bottom.
| lindenstark wrote:
| Daniel Cuthbert did something quite similar[0], with pollution
| sensor from ikea.
|
| [0] https://twitter.com/dcuthbert/status/1421822958604062726
| Animux wrote:
| See also this: https://github.com/Hypfer/esp8266-vindriktning-
| particle-sens...
| Rafuino wrote:
| Any suggestions for a CO2 monitor that doesn't require you to
| solder? I have an Arduino and a breadboard so can hand wire
| things in the meantime if needed...
| karmelapple wrote:
| I really like my Aranet4, although it costs a little over
| US$200. No soldering though, and its been running on one
| battery charge for over half a year!
| BoorishBears wrote:
| In theory there's no reason you can't use a breadboard jumper
| kit and splice it to the cable that the sensor comes with
|
| But soldering has a very low cost-of-entry, and even using
| solderable breadboards over solderless can make your project a
| lot easier to use (no more worrying about lose connections or
| capacitance issues)
| Scene_Cast2 wrote:
| For some context, PurpleAir also uses Plantower dust sensors. As
| an alternative, there's also the Honeywell HPMA sensors (used in
| Awair).
| philips wrote:
| It is too bad that PurpleAir doesn't do CO2 last I looked. I
| really want a single device.
| Scene_Cast2 wrote:
| My old Awair has a Telaire T6703 CO2 sensor; the newer ones
| probably have something similar. I also had a standalone
| sensor at one point, they're a thing too.
|
| And Tindie has a slew of ready-to-order air quality stations
| too.
| philips wrote:
| Have you had a good experience with Awair? The last time I
| looked it seemed like they had no recommended way to clean
| the sensors. And in my limited experience PM2.5 sensors do
| need periodic cleaning to remain accurate. My air filter
| has one and the manufacturer recommends a bit of alcohol
| and a puff of air.
| Scene_Cast2 wrote:
| Their old one had an issue with the dust sensor clogging.
|
| The new ones use the Honeywell sensor. It has a tiny fan
| on it (inaudible in a quiet room from 5 inches away);
| mine ran well for a couple of years until I knocked it
| off my desk. After that, the fan started rattling, so I
| ordered another Honeywell sensor ($40) and replaced it
| (no soldering required, just a screwdriver). That
| sensor's datasheet doesn't have any cleaning
| instructions, so I don't think it's a big issue.
| philips wrote:
| Ok thanks
| personjerry wrote:
| Is there a non-DIY version of this, preferably <$100? I often
| have breathing difficulties and would be curious to see if
| humidity, CO2, and pm2.5 are affecting me, but I don't have a
| soldering kit.
| outlog wrote:
| think the Qingping air detector lite fits the bill -
| https://www.youtube.com/watch?v=FVzwBGf6woo - available on
| amazon or aliexpress etc.
| newbamboo wrote:
| Bought a monitor because aqi near me averages 50-100 during
| summer, pre-fire season.
|
| Found my tvoc is constantly in .70-1.0 mg/m3 unless I open all
| windows and run fans. Then it drops to around .6 mg/m3. I now
| don't worry at all about pm2.5 levels and just keep my windows
| open if the temps below 100. Buying the monitor showed me that my
| migraines and other issues (brain fog) were caused by the high
| voc. Opening windows even if it means breathing wildfire smoke
| makes the headaches disappear.
|
| Anyone out there on the fence about buying a monitor, just do it.
| There are worse issues than pm2.5 and smoke, both of which you
| can detect with your nose.
| ttesttom wrote:
| Did you buy an AirGradient monitor or any brand you recommend
| that is not DIY?
| newbamboo wrote:
| Just the 80 dollar temtop that sells on Amazon. Easy enough
| to check against local purple air sensors for the particulate
| readings. I did that, and they were spot on for my
| neighborhood. Don't know if I trust the formaldahyde reading
| but the tvoc corresponds to my physical experience very well,
| and it drops to near 0 tvoc when taken outside. If there's a
| catch, it's that you don't know what voc you're dealing with.
| Could be something lethal like radon or something fairly
| innocuous at the levels I'm seeing. Whatever it is in my
| case, it causes very predictable migraine symptoms which
| correspond to the voc level almost perfectly.
| macNchz wrote:
| After getting a (non-DIY because as much as I like hobby
| electronics I have a tendency to scope creep my little projects
| straight into incompletion) about a year ago, my main learnings
| have been:
|
| - Cooking is insanely bad for the air in your house, even with an
| outside-venting hood. Any sort of medium-high heat cooking will
| spike the PM2.5 to multiple times that of the haziest days here
| in NYC, and with the windows shut it will stay elevated for hours
| after.
|
| - The 20" box fan + MERV furnace filter hack is super effective
| for cutting down on the PM. A few days this July the wildfire
| smoke from the west coast settled on NYC and we had 40-70 ug/m3
| PM2.5 outside. The box fan filter took it down to around 5 in a
| matter of minutes. I didn't even bother taping the filter to the
| fan.
|
| - My A/C system's ability to precisely hold the temperature
| within fractions of a degree of the thermostat setting is
| impressive.
|
| - With two people working from home in an old, unventilated-but-
| kinda-drafty ~700 square foot apartment, the only thing that gets
| the CO2 levels into "drowsy" territory (my original point of
| curiosity when buying the sensor) is running the gas oven for a
| while.
| throwawaysea wrote:
| There are better setups than the 20" box fan + MERV furnace
| filter. For example check out this similar DIY design that
| reduces risk of an electrical fire by making it easier for the
| fan to draw air: https://encycla.com/Corsi-Rosenthal_Cube
| rovr138 wrote:
| From that page,
|
| >The EPA funded a study by Underwriters Laboratories (UL)
| which tested box fans with MERV-13 filters attached, finding
| them to not present a fire hazard even in extreme, modified
| conditions.
|
| Then it links to, https://chemicalinsights.org/wp-
| content/uploads/DIY-Box-Fan-...
|
| which says,
|
| >Two-Sided Obstruction
|
| >Figure 6 shows the time series of monitored temperatures
| under extreme condition where both sides of the fans were
| blocked. Despite the severe blockage of air flow,
| temperatures of all five box fans peaked within the first 20
| minutes and then plateaued, remaining steady for the
| remaining 7 hours. Winding temperatures had the largest
| relative increase of 30 to 57 degC above ambient temperature,
| with peak absolute winding temperatures remaining at or below
| 80 degC. Peak temperatures on other fan parts did not exceed
| 50 degC.
|
| > Temperatures at the power cord, guard, and switch, remained
| close to ambient room temperature (+-6 degC) during all
| filter test scenarios as well as during the one-sided blocked
| tests. For the two-sided blocked tests, temperatures at the
| power cord, guard, and switch increased initially before
| plateauing to a steady temperature for the remainder of the
| 7-hour test duration. All fans remained operational for the
| 7-hour test duration and did not show any signs of potential
| hazard or damage.
| TrevorJ wrote:
| The gas stove thing was surprising, but of course it makes a
| ton of sense!
| wintermutestwin wrote:
| >The 20" box fan + MERV furnace filter hack
|
| Living here in the west with hyper toxic AQI for the better
| part of two months now, I decided that the low CFM and leakage
| of a DIY box fan are not adequate to keep up. I went with a far
| more industrial solution: I went to an indoor grow shop and
| bought an activated carbon filter and high CFM inline fan. Cost
| $150 and is a bit noisy, but has been well worth it.
| fosk wrote:
| Link?
| jonahhorowitz wrote:
| You can buy carbon activated MERV filters. I got some from
| Nordic Pure.
| rtkaratekid wrote:
| What sensor are you using? Just curious.
| macNchz wrote:
| I'm using an Awair Element, I didn't do a ton of research on
| alternatives, but the app is pretty good and it "just works".
| newfonewhodis wrote:
| I've been thinking of getting it what are your thoughts on
| longevity of it? Will it last at least a few years? I also
| see in some Amazon reviews that measurements get "stuck" to
| some extreme. Have you noticed that too?
| tpmx wrote:
| For DIY, there was a pretty good discussion on suitable
| sensors in the AirGradient post from three months ago that
| Jeff linked to:
|
| https://news.ycombinator.com/item?id=27125060
|
| tl;dr: seems like you want an NDIR sensor (https://en.wikiped
| ia.org/wiki/Nondispersive_infrared_sensor).
|
| Some options, with digikey @1 prices:
|
| Senseair S8 (Sweden): $48
|
| Sensirion SCD30 (Switzerland): $63
|
| Amphenol Telaire T6713 (US): $96
|
| If I were to buy an expensive black box iot solution, I'd at
| least verify that it had an NDIR sensor.
| s0rce wrote:
| I'm using an SCD41 with an OLED+microcontroller (using
| Sensirion's example code hacked a bit) and it seems to work
| well, cheaper than the NDIR using some photoacoustic magic.
| tpmx wrote:
| $37 @1, but not in stock at digikey, and an 11 week lead
| time.
|
| It's pretty tiny... I wonder if/when it will be possible
| to put a high quality co2 sensor in an IP68 iPhone...
| s0rce wrote:
| I had purchased the dev kit sek-scd41 but its out of
| stock as well. The SCD41 also does RH and T so you don't
| need a separate sensor for that.
| karmelapple wrote:
| To add to the list of sensors: I was most curious in CO2
| levels, so I got an Aranet4: https://www.amazon.com/dp/B07YY7
| BH2W/ref=cm_sw_r_cp_api_glt_...
|
| It's got an eink screen, and I haven't had to recharge it
| since I got it 8 months ago. I really like it.
| Robotbeat wrote:
| Are there any affordable CO2 sensors that don't use outside
| air for calibration of ppm? I want to know how outside air
| CO2 levels change as well. Would be interesting to see day
| to day changes and how big they are in absolute terms.
| (Also to show people about how CO2 levels are changing
| globally... without just pointing to a website of someone
| else's measurements.)
| Scene_Cast2 wrote:
| I think the draftiness is key. In my findings, in a "modern"
| house (double-paned windows, built in the last 20 years),
| sleeping with the door closed will spike CO2 to 4 digits. The
| other thing is that air really needs to circulate in order to
| lower CO2 - opening a window in a room will not lower the
| hallway CO2 unless there's at least some draft / air movement.
| 5e92cb50239222b wrote:
| Temperature difference helps if there's no wind. In winter
| time CO2 drops from 4000+ ppm to ~450 in only a couple of
| minutes after opening a single window (with inside to outside
| temperature difference of 50degC or higher). In summer it
| drops to ~600-700 and stays there, and even this takes hours.
| crazygringo wrote:
| That's what I've discovered over the past year! I live in
| NYC and my CO2 levels are fine in both the winter and on
| hot summer days, without even trying.
|
| But when it's 65-75degF outside in the spring/fall... CO2
| builds up in my apartment like _crazy_. I keep the windows
| open and my bathroom fan on to try to suck fresh air in...
| but even so can 't manage to really get it below 650, and
| with just a window cracked it sticks around 850.
|
| It's really frustrating.
| y4mi wrote:
| 50degC difference or even higher? Damn mate, even Siberia
| only gets around -34degC which is less then that of you
| target the usual 18-21degC. Your winters sound terrifying.
| freeopinion wrote:
| Winters? I thought they were referring to this last May
| or the previous August.
|
| https://en.wikipedia.org/wiki/Highest_temperature_recorde
| d_o...
| theluketowers wrote:
| Saskatchewan Canada can easily reach -40degC for several
| weeks during the winter.
| withinrafael wrote:
| Our multi-room apartment in Redmond, WA, has an always
| running intake fan in the master bathroom advertised as a way
| to keep air fresh. I always wonder how effective that really
| is (at apartment scale) and if it's really worth the 24/7
| power draw.
| hourislate wrote:
| It's to keep positive pressure in your unit for safety
| purposes. If there is a fire the fresh air will help keep
| smoke out of your unit and as a bonus it keeps other
| building odors out. Generally it is a large fan on the roof
| that just sucks air down a stack pumping it into every
| unit. You could put a filter over the register and filter
| that air.
| withinrafael wrote:
| Sorry, by intake I meant it's sucking air in. That is,
| air is leaving my apartment. I think you're on the right
| track with the safety angle here though. Will do more
| research.
| zz865 wrote:
| Its probably the opposite, it sucks out air. It does stop
| smells from this apartment going into neighboring spaces.
| asdff wrote:
| Probably more for preventing mold damage from lazy tenants
| I imagine.
| davemp wrote:
| That's why an ERV [1] is important in a modern house with
| good air tightness.
|
| [1]:
| https://en.wikipedia.org/wiki/Energy_recovery_ventilation
| nsporillo wrote:
| In a modern home, there should be supply and return vents in
| every room. My home built in 1978 has 3 returns for the
| entire house, one on each floor. Master bedroom has a supply,
| but the return is located in the hallway. Over the years, the
| recommended door cut to allow air flow has been changed
| (presumably for greater privacy) - which leads to the
| scenario you're describing.
|
| I could add the door cut back in, install return transfer
| grill, or look into adding a secondary heat recovery
| ventilator that acts independently of the primary HVAC
| system.
| geerlingguy wrote:
| I know many people who put 'draft stop' devices on the
| bottoms of their bedroom doors in older homes (old enough
| to not have returns in each room, but new enough for
| central air), not realizing they're cutting off the one bit
| of circulation they need for a proper functioning central
| air system!
|
| Or they buy new high efficiency windows and doors, and that
| 'tightens up' the house, but they don't also install an HRV
| (Heat Recovery Ventilator) to exchange outside air.
| nsporillo wrote:
| Realistically new windows and doors probably wont drop
| the homes air changes per hour below the recommended
| minimums, but I don't know for sure. I've gotten my
| crawlspace spray foamed and I'm getting my vented attic
| spray foamed to bring it into my envelope. Also getting
| new windows and doors soon, but after all of that I think
| enough air could leak through sill and top plates,
| electrical outlets, etc.
|
| Having the foam crew do a blower door test for free if we
| go with them, so I guess I'll see. I live in climate zone
| 5a (cool, humid) so historically natural ventilation was
| used via induced pressure differentials generated by
| mechanical means (dryer, furnace, bathroom and kitchen
| vents). When we get new furnace and water heater that
| pull combustion air from outside, we're left with mostly
| manual means for generating negative pressure that drives
| infiltration. (But also wind, and pressure differentials
| caused by temperatures in winter)
|
| In our case, we're definitely considering either an HRV
| or ERV to supply fresh outdoor air that we control (input
| and output CFM, MERV #). Our indoor air quality is poor
| enough to the point where we live with the tangible
| symptoms (Rhinitis), not just numbers on a sensor.
|
| For those with interest in these topics, I suggest
| skimming a copy of one of the ASHRAE fundamentals
| handbooks[1]. It reads as a textbook but has incredible
| depth into the physical sciences that relate to building
| science, heating, cooling, and ventilation.
|
| [1] https://archive.org/details/ashraehandbook2017hvacfun
| damenta...
| [deleted]
| rootusrootus wrote:
| > In a modern home, there should be supply and return vents
| in every room.
|
| That must vary by region. I live in the PNW, and I have not
| seen a recently built house with a return in each room. One
| or more supply vents per room depending on size, one return
| for each floor seems pretty much standard.
| windexh8er wrote:
| Interesting. I live in the upper midwest and remember my
| first home I lived in (parents built it new in 1980) had
| returns in every room. My current home is primarily
| forced air and there are returns in every room with
| multiples in the larger gathering spaces. Was built in
| the late 90s and I think building code may require a
| specific number of returns per square foot.
| rootusrootus wrote:
| Could be regional -- I would bet that in most cases
| houses in the upper midwest have to deal with much colder
| temperatures in the winter than houses in the PNW. Maybe
| that influences the HVAC design.
|
| But I wouldn't be the least bit surprised to find that
| there isn't really a specific reason, it's just "how we
| do things in this area." A surprising amount of building
| choices seem to be made that way.
| nsporillo wrote:
| The box fan and high-merv filter hack is a good idea, but
| proper ventilation of filtered outdoor air is the best
| solution. Not always practical, but historically buildings
| breath via air infiltration due to pressure differentials,
| stack effects, wind, etc - might as well bring in the air on
| your own terms rather than it leak through your walls and
| insulation.
| Tenoke wrote:
| I'm not actually sure it's always the best. My rooms face the
| street and I can't tell if the air I get on that side is
| actually better than just having air from the other side
| +purifier.
| nsporillo wrote:
| Quality Energy/Heat Recovery Ventilators (which are
| basically mandated by code [in some jurisdictions] in
| modern construction due to air tightness requirements)
| should allow you to select the filter with the MERV value
| that works best for your situation.
|
| But to be fair, you may have a good point. Vehicle
| emissions and tire wear generates particulates consider to
| be ultrafine (0.1 max nanometer), which is even difficult
| for HEPA filters to deal with.
| macNchz wrote:
| On my leafy Brooklyn street the particulate pollution outside
| is well within the recommended levels nearly all the time, so
| thankfully there's not really a pressing need to retrofit
| modern ventilation into a 120 year old house. That is,
| assuming the presence of wildfire smoke from 3000 miles away
| remains a rare event, which...who knows.
| jozzy-james wrote:
| - Cooking is insanely bad for the air in your house, even with
| an outside-venting hood.
|
| weeps in searing steaks with no hood at all :'(
| jeffwass wrote:
| If someone knows the answer to this I'd be interested to know :
|
| Do different PM2.5 components affect the body differently, even
| for the same overall count?
|
| Eg, are the PM2.5 particulates from burning toast comparable in
| bodily health impact to a similar PM2.5 count coming from a
| heavy Diesel engine's exhaust (which I presume would have a
| different particulate makeup).
| pirate787 wrote:
| My understanding is that PM2.5 with heavy metals or toxic
| payloads is more dangerous, but both are dangerous.
| goodpoint wrote:
| > - Cooking is insanely bad for the air in your house
|
| Hold on! Not all particulates are equally harmful - and by far!
|
| A particulate sensor detects water vapor or particles of (non-
| burnt) cooking oil that are harmless to humans.
|
| In the same way, it detects very dangerous (carcinogenic)
| compounds from combustion engines or burning coal or wood.
|
| Cooking is in no way "insanely bad" (unless you are grilling
| your food black or cooking on an open wood/coal fire)
| macNchz wrote:
| I am able to find many journal articles confirming my
| observations that cooking produces significantly elevated
| indoor PM2.5 levels, many of which suggest it to be harmful,
| but I'm not finding anything about the relative impacts of
| the different substances that make up fine/ultrafine
| particles. People involved in this research seem to think it
| will require more study:
|
| >"We know that inhaling particles, regardless of what they're
| made of, is detrimental to health. Is it equally bad as
| inhaling exhaust from vehicle emissions? That we don't know
| that yet," [1]
|
| Regardless, my sensor, at least, doesn't register water vapor
| as particulate. I can run an ultrasonic humidifier with
| distilled water to no effect on the measured PM2.5, or with
| tap water which will spike the particulates from the
| dissolved minerals.
|
| 1) https://www.theguardian.com/environment/2019/feb/17/cookin
| g-...
| 5e92cb50239222b wrote:
| It does not measure water vapor, at least not the one I'm
| using (PMS5003). I always have windows tightly shut because
| of the extreme pollution outside, so 100% humidity is easy to
| reach simply by mopping the floors (which stay wet for hours
| after). It does not change PM measurements one bit. Fry a
| couple of eggs though, and PM 2.5 quickly goes over 100
| ug/m3. Burn a piece of meat just a little bit and see it rise
| over 300 ug/m3.
| eutectic wrote:
| What about suspended water droplets?
| crazygringo wrote:
| The thing that sends my PM2.5 skyrocketing the most is,
| interestingly, my toaster oven. Like from 50 to 1500 in the
| space of 10 min. No food needed within -- just the heating
| itself.
|
| I have no idea what the particles are though -- metal? Paint?
| Carbon from burnt residue? Or just whatever the heating
| element itself is made of?
|
| Separately, cooking with gas (oven+stove) also sends CO2 way
| way up -- in my kitchen, from 500 to 1300 or so within 20
| minutes. And that's with my range hood _on_.
| sneak wrote:
| A lot of range hoods don't actually exhaust outside, and
| just suck stovetop air over some steel wool to condense the
| grease particles somewhere other than your walls.
|
| Not saying that's the case here, but several times I
| thought the range fan was exhausting the air, only to learn
| upon examination that it was just shooting it back out into
| the same room.
| klondike_klive wrote:
| The last place I lived in - the cooker hood did exactly
| this, without even the steel wool. We noticed a growing
| stain on the ceiling and found out there was no outlet,
| no filter, just a fan blowing the greasy air onto the
| ceiling. This was a 1 bedroom apartment with one of the
| ubiquitous "kitchenette"s that are fitted these days, so
| that landlords don't lose a whole room to a kitchen that
| exhausted commuting professionals will never use.
|
| Our current place has a proper kitchen, but the cooker
| hood vents outside directly next to the central heating
| boiler's intake.
| thrashh wrote:
| Dust in the toaster?
| goodpoint wrote:
| Carbon from burnt residue, most likely, and that could be
| quite unhealthy. Clean the toaster!
| crazygringo wrote:
| Thing is you can't really deep-clean it... it's not
| particularly dirty, I keep the bottom free of crumbs
| etc., but when oil droplets from food collect against the
| back surface and polymerize there, what can you do...?
|
| You can't exactly throw the toaster oven in the sink and
| scrub the inside surfaces with steel wool and Barkeeper's
| Friend under running water like you can with pots and
| pans. Nor do toaster ovens have a "self-cleaning" cycle
| where you try to just vaporize it all... they simply
| don't get hot enough.
| JoeDaDude wrote:
| This is one of the selling points of induction stoves, but
| you will have to balance air quality with exposure to high EM
| fields.
| nyghtly wrote:
| You're leaving out the most important part: cooking with gas.
|
| "Natural gas and propane stoves can release carbon monoxide,
| formaldehyde and other harmful pollutants into the air, which
| can be toxic to people and pets."
|
| https://ww2.arb.ca.gov/resources/documents/indoor-air-
| pollut...
|
| "Gas stoves can generate unsafe levels of indoor air
| pollution"
|
| https://www.vox.com/energy-and-
| environment/2020/5/7/21247602...
| goodpoint wrote:
| No, I'm responding to the statement about particulate.
| Gasses are a different topic.
|
| Also, the dangers of open flames are well known, unlike the
| ones of particulate.
| tootie wrote:
| Not an expert but from what I've read, gas stoves are by far
| the worst. Electric (including induction) are much healthier.
| karmelapple wrote:
| Agreed with all these observations, especially gas oven or
| stove usage! Our former third floor ~1200 sq ft condo would
| spike CO2 up well over 1400 ppm when we'd run it, and almost
| instantly.
|
| Even just with two people working from home, much of the space
| would quickly get up to 800 or 900 ppm. I'd usually open
| windows as I saw it creeping up, which would quickly reduce CO2
| to under 600, and then it would slowly creep up over the day.
| Someone1234 wrote:
| > I didn't even bother taping the filter to the fan.
|
| I found bungee cord with J hooks works really well. As you
| correctly point out, you don't _need_ to secure it at all, but
| it is annoying to tap the box fan and have the filter fall
| over.
| lisper wrote:
| That seems odd to me. I've never tried this, but it seems to
| me that you have to put the filter on the intake side of the
| fan, other the fan would just blow it off. And on the intake
| side, would not the pressure differential hold it in place?
| wholinator2 wrote:
| I feel like you could place it on either side of the fan as
| long as air is directed to go through it. My personal
| intuition is filter then fan but I don't see a reason it
| couldn't go the other way. I wonder why most devices place
| it on the intake though. Maybe to prevent dust from getting
| inside a device, but even then it'd only protect the fan
| from dust. Hmmm...
| r00fus wrote:
| When the air is good outside, I typically run our whole-house
| fan pulling in outside air while I'm baking or making dinner -
| didn't consciously decide on it, but it just seemed to feel
| better to do those together.
|
| Now I really need to investigate more details - like does
| induction cooking (vs. gas) improve the quality? What about the
| type of food (ie, cooking vegetarian vs. grilling sausages)?
| beenBoutIT wrote:
| Investigate fume hoods and implement a good one with enough
| make-up air to take everything coming off of your range out
| of your kitchen. Air quality's negatively impacted by heating
| pots/pans/etc. and their contents up and less about how
| they're being heated. With the exception of h2o just about
| everything you cook has a negative impact on the air quality
| and the pans themselves are doing all sorts of interesting
| things to the air when they get hot.
| hadlock wrote:
| > the components for this project cost between $60-80
|
| Purple air sells a turn key indoor air quality device for $200,
| is very reliable, also comes in a (clear) 3d printed case, comes
| with power supply. Not as DIY as this guy's solution, but with
| limited time on my hands the $100 was worth the cost of
| admission. It also works with Purple Air's map which provides
| nationwide air quality, temp and humidity, etc which is really
| nice.
|
| It's worked flawlessly for me now for about five months. The
| light turns from green to yellow when I open the window in my
| south facing condo, but turns green again when I close the window
| and turn on the air filter. I was surprised at how bad the air
| quality gets when cooking food on the stove.
| goodpoint wrote:
| I wish there was a credible, volunteer run indoor/outdoor
| pollution map.
|
| With cheap probes and peer-review software (properly packaged in
| Linux distributions).
| gruez wrote:
| FYI to the author: you can get tiny screws off ebay/aliexpress.
| They're under $2 for 50-100, including shipping.
| geerlingguy wrote:
| True, I just don't have any that small on hand. I have a few
| boxes of M2.5 and M3, but none smaller.
| jvanderbot wrote:
| I did a similar thing -- set up AQ sensors in the house.
|
| I used the sps30 from sparkfun, CAD'd up a panel mount, 3d
| printed it, built a wooden box for it + a pi, set up all the
| networking and hosting, and packaged my utils for debian.
|
| Anyway, the AQ is fine, HEPA filters work when in-line with the
| A/C, and there's nothing much to monitor even when AQ is mod/bad
| outside. Boring, but nice to know, and fun to learn all those new
| skills.
|
| Just don't burn incense.
| sneak wrote:
| Or standard paraffin candles! The soot (even when they burn
| normally/"clean") is killer.
|
| I have some beeswax ones coming soon which are supposed to be
| better; my PM25 meter is standing by for their arrival.
| jvanderbot wrote:
| I bought some electric candles. They can go months on a AA
| nimh battery, and if you pay enough for them, they are
| actually good / realistic enough for the wife's relaxation.
| Great for power outages as well.
| throwawaysea wrote:
| Is there a particular "expensive" model you would recommend
| for realism?
| jvanderbot wrote:
| These work really well, and seem to actually be made of
| wax so the candle looks quite good. Note the "wick" is
| sunk in an inch or two so there's nothing to really
| suspend disbelief.
|
| Also they have an optional 24-hour timer so they'll
| remember to turn on the same time you turned them on
| yesterday.
|
| https://www.potterybarn.com/products/flameless-outdoor-
| candl...
| sneak wrote:
| I like fire, and I like dripping wax, and I have really
| nice sterling candelabras that look quite spiffy on my big
| table bedecked with a half dozen long black taper candles.
| eulers_secret wrote:
| I feel the same way. Electrics are neat, though -
| especially if you make your own:
| https://cpldcpu.wordpress.com/2016/01/05/reverse-
| engineering...
|
| But I just like the 'ambiance' too much. There are always
| different levels of risk adverseness: if I was
| considering candles a pollution health hazard I should
| also stop riding motorcycles, vaping various things, and
| stop eating like I do...
| blacksmith_tb wrote:
| That has been my experience too - unless you put your monitor
| in your kitchen, in which case frying or baking will usually
| cause a pretty significant spike...
| Scene_Cast2 wrote:
| I'm currently building an adapter to mate furnace filters to
| quiet, high static pressure fans. This should keep the same
| volume of filtration as a box fan, but lower the noise
| significantly. I'll probably be ordering a batch of 5-10, if
| interested, email me (link in profile). Or comment, as long as
| you have an email in your profile, I suppose.
| smiley1437 wrote:
| I'm interested
| Scene_Cast2 wrote:
| Do you have an email or a way to reach out? I didn't find one
| in your profile.
| smiley1437 wrote:
| updated my profile thanks
| fotta wrote:
| Probably worth noting that the South Coast AQMD tests various PM
| sensors from consumer-grade to lab-grade and publishes results
| [0]. Lots of cheaper consumer-grade sensors outperform the
| expensive lab-grade sensors.
|
| [0] http://www.aqmd.gov/aq-spec/evaluations/summary-pm
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