The more we study it, the more we learn how harmful the air inside our homes is.
That's why fresh air is key. Crack a window or two open. Buy an air monitor that monitors CO2 (good proxy for overall freshness), VOCs (sometimes these build up much faster than CO2), and PM2.5.
If CO2 or VOCs are high, open windows more. If PM2.5 is high and coming from outdoors, turn on an air filter.
Yes, this means your heating and cooling bill will be a bit higher. But for your health and concentration, it's worth it.
This is advice that gets thrown around a lot, but it's missing the important bit of how to buy a meter that's both reasonably accurate and affordable. There are countless articles online showing how widely commonly sold meters vary in their readings. What's more, paying more often does not mean you'll get a more accurate reading. Sure, there's diminish returns and past a certain point it doesn't matter, but many meters are completely unreliable.
The problem is there are a lot of effectively 'fake' CO2 monitors. They can't monitor CO2, they only monitor something else and work backwards to estimate CO2 levels.
The cheapest real ones I've found are on the order of ~$150
I tried to do this (buy an affordable priced, reasonably accurate meter) and, after probably after reading the same articles as you, reached the conclusion that there are no meters that are accurate and affordable.
So many seem to rely on automatic ‘calibration’ - which just seems to consist of “let’s assume the lowest sensor readings of the last while correlate to baseline atmospheric CO2”.
For a meter that’s never taken outside, this is obviously going to mean it’s reading too low all the time after a few ‘calibration’ cycles. And, worse, it's likely to be more wrong in less well ventilated spaces.
I have an "INKBIRD WiFi Indoor Air Quality Monitor" (INK-CO2W) and consider it useful and reliable for my purposes.
You calibrate it by setting it outside for a bit to establish the baseline and then bring it inside. The detected CO2 level noticeably tracks with the number of people in the living room in which it is located and whether outside air is being pulled in, either due to the furnace or having multiple windows open.
We do not use the app, so I can't comment on that. And my only complaint is that it has to be plugged in otherwise it runs out of power in an hour or two.
The challenge with opening the window isn't even the cost - which is substantial - from about £250/month to £400/month if I have my windows open even a little bit.
The bigger challenge is with my windows open, my heating just can't even keep up! It'll be maxed out and only 18c.
I do the German-style luften twice a day, but if our interiors are just absorbing the compounds and releasing it when the windows are shut, then that's not even going to help much.
It is called recuperator. If it is possible to retrofit i suggest to use mounted in attic (it will be silent). Otherwise, if you want higher quality not and these `breathing` types the box will have similar size like air conditioner (search: mitsubishi vl-100eu5-e)
Indeed, but a traditional MVHR would require ductwork which isn't common in the UK and often there isn't really any space to route it.
I have been investigating easier to retrofit decentralised MVHR systems such as the Prana Recuperator, Ventaxia Tempra and the Blauberg Vento. They can be noisy (not a problem for me, I don't mind noise) and quite expensive as you have to fit a number of units in different rooms, but still easier than retrofitting ducting.
We have low-voc foam in the attic, which outgasses voc’s slowly and constantly. (They measure voc release at application time, not over the product lifetime).
I started actively venting the attic a two months ago. The whole
house reeked of foam for a week or so whenever the windows were closed.
It’s fallen off a lot, even though the attic foam is 5 years old.
I think the sponge analogy is correct. If the house is sealed, the VOCs accumulate in the atmosphere, and are reabsorbed into the foam at the rate they are released into the air.
If you leave the house completely open, the outgassing will not be offset by reabsorption.
I think the CO2 in our place accumulates faster than the VOCs I can smell, so opening the windows when the meter tells us to keeps the net rate of outgassing high, and the indoor pollution low. It seems like the outgassing is slowing down now.
You’re replying to somebody from the UK. They want it warmer than 18C inside. In winter it is typically much colder than this outside so they’re saying their heating won’t get the house warmer than this even if windows are only cracked open.
> The minimum house temperature your home should be kept at to avoid damp, mould and condensation is 18°C, according to health and energy experts.
That article and the supposed experts are idiotic. Condensation is a function of relative temperatures and humidities. If your house is warmer than outdoors, then you're not going to get condensation from outdoor air.
The outdoor air isn't really relevant, the issue is human activity (breathing, showering, laundry, etc.) raising the indoor humidity when combined with low indoor temperatures causing surfaces to approach the dew point. Particularly external walls or windows that will be a lower temperature than the room as a whole.
At 70% RH and 15C air temperatures, the dew point is 10C - which could easily be achieved along the exterior walls of an older more poorly insulated house.
Spindly old grandmothers can crank the thermostat. Everybody else who cranks it then proceeds to whine about the cost and air quality is being an idiot. Put on a sweater.
Every home should have a heat recovery ventilation system. It gives you fresh outside air in the whole home, but filtered to remove PM2.5 and without the inefficiency.
I built a window vent with a variable-speed computer fan and an esp8266 that communicates with a CO2 monitor and raises the speed when the CO2 gets too high. I have a very fine mesh on the window screen that's designed to filter out pollen and dust. It works really well. I usually only turn it on at night, because that's when my wife and I are both in the room and the CO2 can really build up.
I've been using the Awair Element for years. It helped me decide to install an air exchanger an to swap the gas range with induction. Bonus, it has a local API for pulling data.
I have a purple air sensor outside. One day I'll get around to making the air exchanger smart enough to turn off when the smoke from fires makes the air outside worse than inside, it turn off the air exchanger when inside air is good enough, etc.
I've been happy with the AirGradient One, which does have VOC measurement, as well as CO2, and PPM 2.5. It seems that VOC on the hardware side is relative, so the amount is just compared to a baseline (last 24 hours in the case of the AirGradient One). Also, VOCs are everywhere, but not necessarily harmful: cooking will spike your VOCs, but that's very different than having a can of varnish open.
I bought an aranet 4, it's quite eye opening how you sometimes get a lot of CO2 buildup without even noticing.
I mostly solve any issues with VOC by "Stosslueften", but if that's not enough because the air quality outside is too bad, a CR box is an effective, easy to build and almost perfectly silent design, especially if you do it with decent quality pc fans.
Ah, my bad, I thought that everyone built CR boxes with carbon, but that's not the case. The standard design doesn't use carbon at all. Thanks for the correction.
Outside air isn’t a panacea. There is often plenty of pollution right outside your window unless you live on an idyllic beachfront property. The humidity level outside is also rarely what you want in your home, whether it is too high or too low.
Much better than cracking a window is the use of ERVs (energy recovery ventilators) and air filters on the incoming air.
An ERV is a fairly simple device that exchanges air with the outside while mitigating the loss of energy and humidity.
Any modern home build likely has an ERV as part of the design, but it’s not like they can’t be retrofitted, and I’ve even seen some DIY-friendly window unit ERVs (but I’ve never heard if those are any good).
> Any modern home build likely has an ERV as part of the design
Sounds very country dependent. I really doubt it's true here in the UK. But then, UK housing is just garbage all around unless you build something custom and put a lot of money and attention into it.
Yes, I meant in the US. Apologies for not making that clearer. I don't think ERVs are uncommon in new construction outside the US, but I don't know as much about that.
I installed an ERV system in my very small and very old home. It was quite a bit of work, but nothing terribly difficult. Finding a suitable spot for the ERV unit was the biggest challenge: it is quite bulky and not silent, and you need to be able to route ducting to it from all over the house.
It's easily the favourite thing in my home. It filters the outdoor air, reducing pollen and mosquitoes. It keeps out excess moisture in summer. I don't have to open a window when it's cold. It automatically goes into overdrive after a particularly steamy shower. It's great.
Could you share which one you installed and under which circumstances? I'm running two mobile HEPA air filters; not very efficient nor very effective I'd assume.
I have a Zehnder ComfoAir Q350. Overall I'm very happy with it. My only regret is not having installed the optional additional filter box. Due to the limited space and the place I've installde it, it's not feasible to retrofit it.
I live in an apartment in Washington DC. Opening a window reduces CO2 and VOCs. An ERV is great if you can afford it, but cracking the window is still quite reasonable.
CO2 and VOCs, but what about PM2.5 and PM10? What about pollen? What about humidity control?
Cracking a window is also costly, since it directly raises your heating and cooling bills. It's just an "invisible" cost that's easy for some people to ignore since it's hard to directly measure. An ERV pays for itself over time, so it's more a question of whether you can afford to just crack a window?
Living in an apartment makes this difficult because your landlord may not let you improve this situation, but just ignoring the cost of opening a window doesn't make the cost go away.
I live in the DC area and whenever I hear people say "just crack a window" I think, that brings in all of the pollen I'm allergic to in all seasons except winter, plus humidity and 95 f degree heat if it's the summer... I' be been looking into getting an ERV for a while.
The humidity and temperature are rough. Some months I can't open the window at all. This month has been pretty good though, huh? At least for the temperature and humidity.
I feel you about the pollen. I use a Blueair filter, and that keeps PM 2.5 and PM 10 in check.
Don't leave your windows open all the time. Open them for 5-10 minutes at least once a day. Heating air is cheap, it's heating all the other mass in your home that's hard, so don't let it cool down.
If you live somewhere uninhabitable like Texas, change heating for cooling.
The GP comment is technically correct, if somewhat incomplete. A 40 m3 room (about 14’x14’x8’) has about 50kg of air in it; that’s only ~300 Wh to heat every molecule of it by an entire 20C. The thermal mass of the other things is orders of magnitude larger.
The reason that I consider that explanation somewhat incomplete is the behavior of the air and the embodied energy. Imagine it’s winter, the exterior air is quite dry, and you open a window. You will easily lose a large amount of moisture, making the air uncomfortably dry. So you turn on a humidifier, but that will cool the room further with the evaporation of water. You also have to consider convective heat transfer. The fast-moving air is quite good at transferring heat to the outdoors. So, even if you don’t care about humidity, you will lose a lot of heat through convection.
But yes, strictly speaking, the thermal mass of the air is very low in most structures and situations.
I've got one laptop case where it is quite spongy with panels like neoprene and some stretch fabric. When I ride about half an hour with a driver who is not smoking but had smoked in the vehicle (supposed to be always with the windows open out of courtesy to the other drivers), the next morning when I pick up the laptop it smells like tobacco and it takes a few days to go away. This doesn't happen with the backpack which is not built like that.
You can also take the domestic calculations further.
If you have 50 kilos of dead weight for instance, whether it's a set of workout weights or a piece of furniture, and it's all a stable 10 degrees C through and through, it's going to take 50 kilos of 30 C warm air constantly coming into intimate contact with the dead weight however long it takes before your dead weight gets to 20 C and the air does too.
That can be a whole lot longer without forced air. But it still takes 50 kilos of air no matter what.
>the thermal mass of the air is very low
This is exactly it, along with heat exchange capacity.
If you pull out the water hose you could spray it down with 50 kilos of water in no time, but not everybody's living room can withstand that :)
Now if you had 500 kilos of 20 C furniture along with everything else, and you opened your windows and let out the full 50 kilos of air which was fully replaced by 0 C air, then shut the window to achieve a closed system once again, you'd still be sitting on 20C furniture for some time and only breathing 0C air for a short period before the overwhelming mass of the furniture itself warmed the much lesser mass of air right back up a few degrees, and to about 18 C eventually. Which none of the other heated mass will drop below.
With no additional heat added, assuming insulation was perfect, but that's the number of degrees lost from one single full air exchange alone under those conditions.
While the windows are open is the time to vacuum the carpets, drapes and furniture so you can get some forced air through them and let absorbed irritants out instead of just stir it up and move it around. The high-surface-area porous materials can soak up more than you think.
Air exchange matters again because some of the irritants are not the kind that evaporate or "dissolve in air" very fast, and they might have had all kinds of continuous time to accumulate.
You've got to figure that curtains can hold grams of unwanted stuff in their pores from previous bad air days, furniture ounces & carpets pounds plus a lot of the latter is solids which may give off odors or stir up allergens for quite some time once it has gotten into the pores and other tortuous passages. That's a lot of air exchange when you do the math.
Change your air filter after stirring things up and breathe easier after that :)
Can you link an example of a window unit ERV? I tried searching briefly, and came across some folks hacking together units to make them work with windows or adding their own ducting, but nothing analogous to a simple window air conditioning unit. As a renter of an apartment in a very much not modern home, I don't really see anything that seems like it would work.
A couple examples I see on Google. I'm not advocating for any of these, because I have no idea if they are any good, but I see no technical reason an ERV couldn't work as a window unit. Maybe it's an underserved market and someone should make a business out of that.
Yes, consider spores from harmful microorganisms that are released during building work or harmful airborne particles from transport vehicles. Its not as simple as: open the window!
If you have ERVs and filters then amazing. That's still outdoor air.
Yes you have to take into account running an air filter for PM2.5, closing the window while a truck is idling outside, running your humidifier or dehumidifier if you want.
But you need fresh air coming in somehow, at a certain rate. There's no way around it. Pollution in terms of VOC's, and CO2, is always higher indoors than outdoors, because things indoor generate it and don't remove it.
> Most people don't, and cracking a window is the only option.
It's not usually the only option. Installing an ERV is an option for the more than half of the population that owns their own property in the US, and an ERV will save money and pay for itself compared to opening your windows, in addition to the other benefits.
For renters, that's where the window units I mentioned come in, but there aren't as many options there as I would hope yet. If people don't ask for ERVs en masse, then apartments won't offer ERVs as a benefit to attract tenants unless they are legally required. Helping people understand that options exist seems like the first step to changing things. Ideally, even window-unit ERVs wouldn't be the only option for renters. Nearly 90% of households in the US have air conditioning now (which I believe includes rentals), because people asked for air conditioning and were willing to pay for it. ERVs have the added benefit that they don't just make things better, but they should pay for themselves in energy savings too. Maybe I'm too optimistic. I believe the 2024 IECC building codes make ERVs mandatory in new construction in climate zones 6 through 8, as one example of a change that is coming.
My cheap Chinese PM2.5 sensors (PMS7003) installed both outside and inside provide accurate readings all year round. They track official government data very closely (monitored by expensive and certified equipment that goes through calibration every year).
My problem with this advice is not that it's difficult to measure pollution levels (it really isn't), but that there's no "fresh air" outside for many of us. In many parts of the world, the air is significantly worse outside than inside even without running an air purifier (and with a purifier the difference in particulate levels can run into 100× or more during winter).
Some years ago I looked at the few papers that measured the difference in gaseous pollutants (like NO2 and SO2) inside and outside with windows open and windows closed, and for some reason closed windows do provide limited protection against them. Nobody really understands why AFAIK, it shouldn't work that way since they're mixed with air in a gaseous mixture from which they can't be filtered out without a specialized chemical filter, but it does help.
We should clarify what type of sensors we're talking about. It seems to be easier to find accurate inexpensive sensors for particulate matter (PM) and CO2 than it is for VOCs.
> and with a purifier the difference in particulate levels can run into 100× or more during winter
No surprise. A lot of homes are still being heated by combustion. Gas heating is relatively clean if the burners are properly maintained, oil burners are a hit and miss, but everything else... wood pellets are often declared as the "green" alternative, but that's only valid for CO2 (and even there, the actual benefit for the climate is massively debated) - these things spew an awful lot of particulate emissions, brick-wood ovens are even worse, especially when people illegally throw in too humid firewood or, worse, garbage that has no business being incinerated outside of an industrial high temperature facility with proper exhaust stack treatments.
Unfortunately, as you say, in many parts of the world people are too poor to afford proper heating fuel sources, and it's costing them and their countries so much productivity and money in the long run... and in developed countries, there still are a sizable amount of people who have no idea how to properly heat their ovens, how to prepare their firewood or that just outright skirt garbage disposal fees. Jörg Kachelmann, founder of the weather service Meteomedia, has extensively written about that topic in the past [1] and keeps ranting on social media about it under #holzofengate.
Exactly this. Is my Awair Element perfectly accurate? No, but VOC at 200 or less when the windows have been open (on a good air day) looks very different than 3,000 when we finish cooking something on the stove.
Maybe my numbers should be 100 and 10,000, but it doesn't matter, I know when I need to turn the air exchanger on turbo and when we are back to "normal".
> Yes, this means your heating and cooling bill will be a bit higher.
Not even necessarily. People these days are accustomed to keeping their homes at comfortable T-shirt temps even in the dead of winter, but if you dress appropriately for the season you can drop your indoor temperatures 20F or more from what people normally set the thermostat to while still maintaining a safe margin to keep your pipes from freezing.
Yeah, also: The walls are covered with vapor-permeable lime plaster. the idea is to let a contractor specialized in this knock it all off. I have heard that there‘s probably lead in there from leaded gasoline, could be bad for health.
I'm asking myself if building a DIY setup or buying something like Airthings Wave Plus will actually track these compounds at decent accuracy - and if anyone here has gone down this rabbit hole for family health?
From what I've gathered, consumer devices hit acceptable accuracy for CO2/temp/humidity but PM2.5 is hit-or-miss, and VOC readings are more "relative change indicators" than absolute values..
DIY with Home Assistant is more work/fun yes but again only gets similar accuracy AFAIK (with potentially better automation)..
You can (within reason) calibrate these cheap CO2 easily with esphome and an outdoor air reference point overtime. I’ve had to do it for thermometers as well.
This is why your plastic ketchup bottle still smells like ketchup after washing it multiple times - at a microscopic level, plastics essentially look like uncooked ramen/instant noodles, basically a big tangle of polymer chains which act like a sponge.
Now, consider what happens when you wash that plastic with a cocktail of chemicals in your dishwasher...
Obviously very hard/dense plastics (melamine comes to mind) are less prone to this
The article doesn't seem to have immediate actionable recommendation, and is mainly a brick in a wall that can lead (or not) to better design decisions.
One unclear point for example is what happens with the deposited toxins, how hard is it to clean them? are they transferred by touch?
Well, it's a classic research paper. They're essentially only supposed to report findings.
If you live in a house with central HVAC, a decent, regularly replaced filter will help a lot (make sure to only use full blown HEPPA filters if your furnace supports it otherwise you'll have all sorts of airflow issues). Otherwise you can buy air purifiers. The study measured smoke (cigarette and wildfire) as well as insecticides, so minimizing exposure to both is probably the easiest first step (not smoking inside is easy, but wildfire depends on how porous your house is).
The study is about VOCs. You’ll want a carbon filter, as even a HEPA filter won’t do much.
Also, don’t put a HEPA filler in your HVAC return — not only is it unhelpful overkill, it will have excessive static pressure drop, thus wasting power, increasing noise, reducing airflow, and potentially damaging the blower. Use an appropriate filter in the MERV 13-16 range.
Carbon filters in air purifiers are a pain. They do work, but due to their smaller volumes they tend to get full quite fast and require frequent replacements.
If you're considering one, make sure to get an air purifies where the carbon filter can be changed independently from the main filter.
Having moved into a home previously owned by a chain smoker ten years prior, I have no problem believing this. We've had to run ozonators in rooms repeatedly to finally get the smell out.
I've toured a '60s era Cold War diesel-electric sub that's been a museum for ~20 years, and it still absolutely reeked of diesel. Combine that with the smell of a couple dozen dudes that haven't showered properly in weeks, and your answer would be not good.
The long-term health outcomes are probably significantly worse for people that served in diesel subs than nuclear because of the constant exposure to fossil fuel volatiles. Just being in there for a 20 minute tour made me feel like I just smoked 20 cigarettes.
Isn't this obvious? I don't know, maybe there are some details of this study that are are scientifically useful, but as a news it's pointless?
Yeah, make sure to get a lot of ventilation, but that doesn't require any study. Even without any any pollutants, indoor air will have a bad quality. And your body deals with minor amount of bad stuff just fine.
> The findings suggest that regular ventilation alone may be insufficient to remove many indoor contaminants. Physical cleaning activities such as vacuuming, mopping and dusting are necessary to effectively remove compounds with high partition coefficients from surface reservoirs.
Yup. Indoor smoker homes are the worst because cleaning alone is often not enough. Cheap landlords just slap a coat of paint on to hide the visible stain, better landlords use nicotine blocker paint that's pretty expensive... but that's only good for moderate smoke. Decent ones run a few ozone generators for a few weeks while no one and no thing is inside, with the added danger that the decomposition products are toxic on their own and the ozone might damage the electrical wiring.
The only actually reasonably safe way to deal with a heavily smoke laden home is to rip out everything where the smoke has seeped into. For the Americans here, that may mean a complete teardown as the cardboard, insulation and even framing wood will be soaked in smoke residue; Europeans have it a bit better because for us, it's usually enough to remove the plaster but leave the brick/concrete walls alone.
Homes that have been affected by fire are often written off for the same reason, even if the fire itself didn't blaze in the home (say, a lower apartment burned off). The smoke seeps everywhere, especially in older buildings where doors aren't airtight or you got bathroom/kitchen exhaust vents without backflow prevention, and fire smoke is orders of magnitude worse in its effect than cigarette smoke - cigarettes are at least plant based materials, household fire smoke is riddled with stuff like dioxine (from plastics) and other highly toxic combustion products.
This is also one of the saddest aspects of retro computing.
Most listings fail to mention whether previous owners were smokers, and most sellers either aren't sensitive to and/or haven't experienced the off-gassing that occurs once devices warm up through actual use.
So this is actually the main reason I'm thrilled about the MiSTer project and the growing number and variety of FPGA-based clones being released today.
I picked up a second hand gaming PC once: 9 months later our entire downstairs floor was still noticeably smelling of their fabric softener despite frequent airings. They’re like sponges.
And some things like arcade machines, you often can't even get them in "no smoker" conditions as they've been installed in arcades, pubs and other venues where a lot of the attendees smoke.
Not good news, it's just better to know, than to not know. These sponges don't take chemicals out of our environment, they trap it and slowly release it where we would need cleanness. These chemicals would have gone away a long time ago, but the sponges kept them there.
Additionally why this is not good news, these materials were not supposed to be sponges to begin with. So, it's like discovering a bad side effect. Again, better to know than to not know, but it's not what one would call good news.
The more we study it, the more we learn how harmful the air inside our homes is.
That's why fresh air is key. Crack a window or two open. Buy an air monitor that monitors CO2 (good proxy for overall freshness), VOCs (sometimes these build up much faster than CO2), and PM2.5.
If CO2 or VOCs are high, open windows more. If PM2.5 is high and coming from outdoors, turn on an air filter.
Yes, this means your heating and cooling bill will be a bit higher. But for your health and concentration, it's worth it.
This is advice that gets thrown around a lot, but it's missing the important bit of how to buy a meter that's both reasonably accurate and affordable. There are countless articles online showing how widely commonly sold meters vary in their readings. What's more, paying more often does not mean you'll get a more accurate reading. Sure, there's diminish returns and past a certain point it doesn't matter, but many meters are completely unreliable.
The problem is there are a lot of effectively 'fake' CO2 monitors. They can't monitor CO2, they only monitor something else and work backwards to estimate CO2 levels.
The cheapest real ones I've found are on the order of ~$150
Unless your CO2 monitor has purge gas to calibrate it's going to underestimate indoor CO2.
They all assume that they will be exposed to atmospheric concentrations of CO2 at least once a week.
In their defense, they usually mention this requirement in the manual.
Sure but do you take your CO2 meter for a walk?
When nobody is home so there's no CO2 being emitted, it goes down to outdoor levels within a couple of hours if your windows are open even a crack.
If you have a meter that shows you a graph on your phone, you can watch it reach equilibrium. It's very obvious.
And in similar vein, when was the last time you read the manual for a household appliance?
I tried to do this (buy an affordable priced, reasonably accurate meter) and, after probably after reading the same articles as you, reached the conclusion that there are no meters that are accurate and affordable.
So many seem to rely on automatic ‘calibration’ - which just seems to consist of “let’s assume the lowest sensor readings of the last while correlate to baseline atmospheric CO2”.
For a meter that’s never taken outside, this is obviously going to mean it’s reading too low all the time after a few ‘calibration’ cycles. And, worse, it's likely to be more wrong in less well ventilated spaces.
I have an "INKBIRD WiFi Indoor Air Quality Monitor" (INK-CO2W) and consider it useful and reliable for my purposes.
You calibrate it by setting it outside for a bit to establish the baseline and then bring it inside. The detected CO2 level noticeably tracks with the number of people in the living room in which it is located and whether outside air is being pulled in, either due to the furnace or having multiple windows open.
We do not use the app, so I can't comment on that. And my only complaint is that it has to be plugged in otherwise it runs out of power in an hour or two.
The Awair Element is the best option for consumers who want something easy and relatively inexpensive.
Hackers may prefer other options.
Awair is awesome and very sensitive but pretty expensive (150€ for mine) but integrates well in HA
The challenge with opening the window isn't even the cost - which is substantial - from about £250/month to £400/month if I have my windows open even a little bit.
The bigger challenge is with my windows open, my heating just can't even keep up! It'll be maxed out and only 18c.
I do the German-style luften twice a day, but if our interiors are just absorbing the compounds and releasing it when the windows are shut, then that's not even going to help much.
Get a heat recovery exchanger.
https://natural-resources.canada.ca/stories/spotlight-energy...
Good advice if you can do it, but this isn't possible for most people, for example if you're renting or you're in an apartment.
It is called recuperator. If it is possible to retrofit i suggest to use mounted in attic (it will be silent). Otherwise, if you want higher quality not and these `breathing` types the box will have similar size like air conditioner (search: mitsubishi vl-100eu5-e)
Indeed, but a traditional MVHR would require ductwork which isn't common in the UK and often there isn't really any space to route it.
I have been investigating easier to retrofit decentralised MVHR systems such as the Prana Recuperator, Ventaxia Tempra and the Blauberg Vento. They can be noisy (not a problem for me, I don't mind noise) and quite expensive as you have to fit a number of units in different rooms, but still easier than retrofitting ducting.
For those prices, buy an Ambient Weather base station along with this CO2 sensor:
https://ambientweather.com/indoor-wireless-air-quality-monit...
We have low-voc foam in the attic, which outgasses voc’s slowly and constantly. (They measure voc release at application time, not over the product lifetime).
I started actively venting the attic a two months ago. The whole house reeked of foam for a week or so whenever the windows were closed.
It’s fallen off a lot, even though the attic foam is 5 years old.
I think the sponge analogy is correct. If the house is sealed, the VOCs accumulate in the atmosphere, and are reabsorbed into the foam at the rate they are released into the air.
If you leave the house completely open, the outgassing will not be offset by reabsorption.
I think the CO2 in our place accumulates faster than the VOCs I can smell, so opening the windows when the meter tells us to keeps the net rate of outgassing high, and the indoor pollution low. It seems like the outgassing is slowing down now.
I really should get some VOC meters.
Why do you need it to be cooler than 18c?
> The bigger challenge is with my windows open, my heating just can't even keep up! It'll be maxed out and only 18c.
They're trying to heat it.
You’re replying to somebody from the UK. They want it warmer than 18C inside. In winter it is typically much colder than this outside so they’re saying their heating won’t get the house warmer than this even if windows are only cracked open.
I think they want more than 18c. 18c is pretty cold to sit in for a prolonged time.
At 18C I wouldn't even put on a sweater. People need to stop being so wimpy. 10C is a good target temperature during the winter.
10C is a great indoor temperature if you want condensation everywhere and eventually mold, but that's a price worth paying to not be considered "wimpy" I suppose? https://www.homebuilding.co.uk/advice/minimum-house-temperat...
> The minimum house temperature your home should be kept at to avoid damp, mould and condensation is 18°C, according to health and energy experts.
That article and the supposed experts are idiotic. Condensation is a function of relative temperatures and humidities. If your house is warmer than outdoors, then you're not going to get condensation from outdoor air.
The outdoor air isn't really relevant, the issue is human activity (breathing, showering, laundry, etc.) raising the indoor humidity when combined with low indoor temperatures causing surfaces to approach the dew point. Particularly external walls or windows that will be a lower temperature than the room as a whole.
At 70% RH and 15C air temperatures, the dew point is 10C - which could easily be achieved along the exterior walls of an older more poorly insulated house.
If only there were some way to circulate expired air out of a building, perhaps with open windows...
My house is bone dry in winter with the windows regularly open. The humidity concern is idiotic.
Good that everybody is the same and when 18°C is enough for you everybody should be fine with it, even children, old people and sick ones.
Spindly old grandmothers can crank the thermostat. Everybody else who cranks it then proceeds to whine about the cost and air quality is being an idiot. Put on a sweater.
Good for you. At 18C my fingers get too cold to type properly and I keep missing keys.
> German-style luften twice a day
Das ist nicht genug und klingt ehrlich gesagt grauslich.
Not German approved.
Every home should have a heat recovery ventilation system. It gives you fresh outside air in the whole home, but filtered to remove PM2.5 and without the inefficiency.
Many new builds will, especially in places with required efficiency standards, but the average house in the US is 40 years old. And leaky as hell.
Can you say more? Maybe link to a useful page or product(s)?
https://en.wikipedia.org/wiki/Heat_recovery_ventilation
I built a window vent with a variable-speed computer fan and an esp8266 that communicates with a CO2 monitor and raises the speed when the CO2 gets too high. I have a very fine mesh on the window screen that's designed to filter out pollen and dust. It works really well. I usually only turn it on at night, because that's when my wife and I are both in the room and the CO2 can really build up.
I use an ikea air filter that just so happens to fit perfectly in the window + a smart outlet and co2 sensors.
I’d like to do a custom build like you so the fan speeds are variable.
Good advice on the CO2 monitor. Cheap and surprisingly effective. I haven't considered the VOC--any recommendations?
As an aside, I open up my window, but sometimes smokers decide to take a break outside and...well. Other times, I have neighbors barbecuing.
If I don't shut the windows quickly I've just replaced stale and somewhat harmful air with oxygenated and definitely harmful air.
I've been using the Awair Element for years. It helped me decide to install an air exchanger an to swap the gas range with induction. Bonus, it has a local API for pulling data.
I have a purple air sensor outside. One day I'll get around to making the air exchanger smart enough to turn off when the smoke from fires makes the air outside worse than inside, it turn off the air exchanger when inside air is good enough, etc.
I've been happy with the AirGradient One, which does have VOC measurement, as well as CO2, and PPM 2.5. It seems that VOC on the hardware side is relative, so the amount is just compared to a baseline (last 24 hours in the case of the AirGradient One). Also, VOCs are everywhere, but not necessarily harmful: cooking will spike your VOCs, but that's very different than having a can of varnish open.
I bought an aranet 4, it's quite eye opening how you sometimes get a lot of CO2 buildup without even noticing.
I mostly solve any issues with VOC by "Stosslueften", but if that's not enough because the air quality outside is too bad, a CR box is an effective, easy to build and almost perfectly silent design, especially if you do it with decent quality pc fans.
A CR box only removes particulates, not VOCs. To remove VOCs, you need a filter with many pounds of activated carbon.
Ah, my bad, I thought that everyone built CR boxes with carbon, but that's not the case. The standard design doesn't use carbon at all. Thanks for the correction.
Outside air isn’t a panacea. There is often plenty of pollution right outside your window unless you live on an idyllic beachfront property. The humidity level outside is also rarely what you want in your home, whether it is too high or too low.
Much better than cracking a window is the use of ERVs (energy recovery ventilators) and air filters on the incoming air.
An ERV is a fairly simple device that exchanges air with the outside while mitigating the loss of energy and humidity.
Any modern home build likely has an ERV as part of the design, but it’s not like they can’t be retrofitted, and I’ve even seen some DIY-friendly window unit ERVs (but I’ve never heard if those are any good).
> Any modern home build likely has an ERV as part of the design
Sounds very country dependent. I really doubt it's true here in the UK. But then, UK housing is just garbage all around unless you build something custom and put a lot of money and attention into it.
> Sounds very country dependent.
Yes, I meant in the US. Apologies for not making that clearer. I don't think ERVs are uncommon in new construction outside the US, but I don't know as much about that.
They are common in new construction in the Nordics as well.
I installed an ERV system in my very small and very old home. It was quite a bit of work, but nothing terribly difficult. Finding a suitable spot for the ERV unit was the biggest challenge: it is quite bulky and not silent, and you need to be able to route ducting to it from all over the house.
It's easily the favourite thing in my home. It filters the outdoor air, reducing pollen and mosquitoes. It keeps out excess moisture in summer. I don't have to open a window when it's cold. It automatically goes into overdrive after a particularly steamy shower. It's great.
Could you share which one you installed and under which circumstances? I'm running two mobile HEPA air filters; not very efficient nor very effective I'd assume.
I have a Zehnder ComfoAir Q350. Overall I'm very happy with it. My only regret is not having installed the optional additional filter box. Due to the limited space and the place I've installde it, it's not feasible to retrofit it.
I live in an apartment in Washington DC. Opening a window reduces CO2 and VOCs. An ERV is great if you can afford it, but cracking the window is still quite reasonable.
CO2 and VOCs, but what about PM2.5 and PM10? What about pollen? What about humidity control?
Cracking a window is also costly, since it directly raises your heating and cooling bills. It's just an "invisible" cost that's easy for some people to ignore since it's hard to directly measure. An ERV pays for itself over time, so it's more a question of whether you can afford to just crack a window?
Living in an apartment makes this difficult because your landlord may not let you improve this situation, but just ignoring the cost of opening a window doesn't make the cost go away.
I live in the DC area and whenever I hear people say "just crack a window" I think, that brings in all of the pollen I'm allergic to in all seasons except winter, plus humidity and 95 f degree heat if it's the summer... I' be been looking into getting an ERV for a while.
The humidity and temperature are rough. Some months I can't open the window at all. This month has been pretty good though, huh? At least for the temperature and humidity.
I feel you about the pollen. I use a Blueair filter, and that keeps PM 2.5 and PM 10 in check.
Don't leave your windows open all the time. Open them for 5-10 minutes at least once a day. Heating air is cheap, it's heating all the other mass in your home that's hard, so don't let it cool down.
If you live somewhere uninhabitable like Texas, change heating for cooling.
> Heating air is cheap, it's heating all the other mass in your home that's hard
Is the air cheap to heat? Even if it were, that still wouldn't solve the other issues that were mentioned.
The GP comment is technically correct, if somewhat incomplete. A 40 m3 room (about 14’x14’x8’) has about 50kg of air in it; that’s only ~300 Wh to heat every molecule of it by an entire 20C. The thermal mass of the other things is orders of magnitude larger.
The reason that I consider that explanation somewhat incomplete is the behavior of the air and the embodied energy. Imagine it’s winter, the exterior air is quite dry, and you open a window. You will easily lose a large amount of moisture, making the air uncomfortably dry. So you turn on a humidifier, but that will cool the room further with the evaporation of water. You also have to consider convective heat transfer. The fast-moving air is quite good at transferring heat to the outdoors. So, even if you don’t care about humidity, you will lose a lot of heat through convection.
But yes, strictly speaking, the thermal mass of the air is very low in most structures and situations.
I've got one laptop case where it is quite spongy with panels like neoprene and some stretch fabric. When I ride about half an hour with a driver who is not smoking but had smoked in the vehicle (supposed to be always with the windows open out of courtesy to the other drivers), the next morning when I pick up the laptop it smells like tobacco and it takes a few days to go away. This doesn't happen with the backpack which is not built like that.
You can also take the domestic calculations further.
If you have 50 kilos of dead weight for instance, whether it's a set of workout weights or a piece of furniture, and it's all a stable 10 degrees C through and through, it's going to take 50 kilos of 30 C warm air constantly coming into intimate contact with the dead weight however long it takes before your dead weight gets to 20 C and the air does too.
That can be a whole lot longer without forced air. But it still takes 50 kilos of air no matter what.
>the thermal mass of the air is very low
This is exactly it, along with heat exchange capacity.
If you pull out the water hose you could spray it down with 50 kilos of water in no time, but not everybody's living room can withstand that :)
Now if you had 500 kilos of 20 C furniture along with everything else, and you opened your windows and let out the full 50 kilos of air which was fully replaced by 0 C air, then shut the window to achieve a closed system once again, you'd still be sitting on 20C furniture for some time and only breathing 0C air for a short period before the overwhelming mass of the furniture itself warmed the much lesser mass of air right back up a few degrees, and to about 18 C eventually. Which none of the other heated mass will drop below.
With no additional heat added, assuming insulation was perfect, but that's the number of degrees lost from one single full air exchange alone under those conditions.
While the windows are open is the time to vacuum the carpets, drapes and furniture so you can get some forced air through them and let absorbed irritants out instead of just stir it up and move it around. The high-surface-area porous materials can soak up more than you think.
Air exchange matters again because some of the irritants are not the kind that evaporate or "dissolve in air" very fast, and they might have had all kinds of continuous time to accumulate.
You've got to figure that curtains can hold grams of unwanted stuff in their pores from previous bad air days, furniture ounces & carpets pounds plus a lot of the latter is solids which may give off odors or stir up allergens for quite some time once it has gotten into the pores and other tortuous passages. That's a lot of air exchange when you do the math.
Change your air filter after stirring things up and breathe easier after that :)
Can you link an example of a window unit ERV? I tried searching briefly, and came across some folks hacking together units to make them work with windows or adding their own ducting, but nothing analogous to a simple window air conditioning unit. As a renter of an apartment in a very much not modern home, I don't really see anything that seems like it would work.
http://www.purifresh.com/erv.html
https://swervair.com/
A couple examples I see on Google. I'm not advocating for any of these, because I have no idea if they are any good, but I see no technical reason an ERV couldn't work as a window unit. Maybe it's an underserved market and someone should make a business out of that.
A much more DIY example that's probably closer to what you were talking about with "hacking together" a solution: https://www.mychemicalfreehouse.net/2023/10/window-mounted-p...
Thank you! You're right that's the sort of "hacked together" solution that looks cool but beyond my abilities, and I appreciate the first two links.
Yes, consider spores from harmful microorganisms that are released during building work or harmful airborne particles from transport vehicles. Its not as simple as: open the window!
If you have ERVs and filters then amazing. That's still outdoor air.
Yes you have to take into account running an air filter for PM2.5, closing the window while a truck is idling outside, running your humidifier or dehumidifier if you want.
But you need fresh air coming in somehow, at a certain rate. There's no way around it. Pollution in terms of VOC's, and CO2, is always higher indoors than outdoors, because things indoor generate it and don't remove it.
> Most people don't, and cracking a window is the only option.
It's not usually the only option. Installing an ERV is an option for the more than half of the population that owns their own property in the US, and an ERV will save money and pay for itself compared to opening your windows, in addition to the other benefits.
For renters, that's where the window units I mentioned come in, but there aren't as many options there as I would hope yet. If people don't ask for ERVs en masse, then apartments won't offer ERVs as a benefit to attract tenants unless they are legally required. Helping people understand that options exist seems like the first step to changing things. Ideally, even window-unit ERVs wouldn't be the only option for renters. Nearly 90% of households in the US have air conditioning now (which I believe includes rentals), because people asked for air conditioning and were willing to pay for it. ERVs have the added benefit that they don't just make things better, but they should pay for themselves in energy savings too. Maybe I'm too optimistic. I believe the 2024 IECC building codes make ERVs mandatory in new construction in climate zones 6 through 8, as one example of a change that is coming.
Those monitors are useless. Unless they're VERY expensive they only show a change over a short period of time
My cheap Chinese PM2.5 sensors (PMS7003) installed both outside and inside provide accurate readings all year round. They track official government data very closely (monitored by expensive and certified equipment that goes through calibration every year).
My problem with this advice is not that it's difficult to measure pollution levels (it really isn't), but that there's no "fresh air" outside for many of us. In many parts of the world, the air is significantly worse outside than inside even without running an air purifier (and with a purifier the difference in particulate levels can run into 100× or more during winter).
Some years ago I looked at the few papers that measured the difference in gaseous pollutants (like NO2 and SO2) inside and outside with windows open and windows closed, and for some reason closed windows do provide limited protection against them. Nobody really understands why AFAIK, it shouldn't work that way since they're mixed with air in a gaseous mixture from which they can't be filtered out without a specialized chemical filter, but it does help.
We should clarify what type of sensors we're talking about. It seems to be easier to find accurate inexpensive sensors for particulate matter (PM) and CO2 than it is for VOCs.
> and with a purifier the difference in particulate levels can run into 100× or more during winter
No surprise. A lot of homes are still being heated by combustion. Gas heating is relatively clean if the burners are properly maintained, oil burners are a hit and miss, but everything else... wood pellets are often declared as the "green" alternative, but that's only valid for CO2 (and even there, the actual benefit for the climate is massively debated) - these things spew an awful lot of particulate emissions, brick-wood ovens are even worse, especially when people illegally throw in too humid firewood or, worse, garbage that has no business being incinerated outside of an industrial high temperature facility with proper exhaust stack treatments.
Unfortunately, as you say, in many parts of the world people are too poor to afford proper heating fuel sources, and it's costing them and their countries so much productivity and money in the long run... and in developed countries, there still are a sizable amount of people who have no idea how to properly heat their ovens, how to prepare their firewood or that just outright skirt garbage disposal fees. Jörg Kachelmann, founder of the weather service Meteomedia, has extensively written about that topic in the past [1] and keeps ranting on social media about it under #holzofengate.
[1] https://www.t-online.de/nachrichten/panorama/id_84671908/kac...
There's a spectrum between "useless" and "good enough", for most people it acts more of an awareness tool and for that it does the job well.
Exactly this. Is my Awair Element perfectly accurate? No, but VOC at 200 or less when the windows have been open (on a good air day) looks very different than 3,000 when we finish cooking something on the stove.
Maybe my numbers should be 100 and 10,000, but it doesn't matter, I know when I need to turn the air exchanger on turbo and when we are back to "normal".
> Yes, this means your heating and cooling bill will be a bit higher.
Not even necessarily. People these days are accustomed to keeping their homes at comfortable T-shirt temps even in the dead of winter, but if you dress appropriately for the season you can drop your indoor temperatures 20F or more from what people normally set the thermostat to while still maintaining a safe margin to keep your pipes from freezing.
Crack a window open (Except if you live in a city)
We have a basement garage in our house which has probably not seen a car since the 80s. It still smells of gasoline.
Concrete absorbs petroleum spills. You may need to identify areas that are stained and do a thorough cleaning to try to extract as much as possible.
Yeah, also: The walls are covered with vapor-permeable lime plaster. the idea is to let a contractor specialized in this knock it all off. I have heard that there‘s probably lead in there from leaded gasoline, could be bad for health.
How do you have a basement garage? I've seen some weird arrangements, but did the driveway have some massive slope or something?
I'm asking myself if building a DIY setup or buying something like Airthings Wave Plus will actually track these compounds at decent accuracy - and if anyone here has gone down this rabbit hole for family health?
From what I've gathered, consumer devices hit acceptable accuracy for CO2/temp/humidity but PM2.5 is hit-or-miss, and VOC readings are more "relative change indicators" than absolute values..
DIY with Home Assistant is more work/fun yes but again only gets similar accuracy AFAIK (with potentially better automation)..
You can (within reason) calibrate these cheap CO2 easily with esphome and an outdoor air reference point overtime. I’ve had to do it for thermometers as well.
This is why your plastic ketchup bottle still smells like ketchup after washing it multiple times - at a microscopic level, plastics essentially look like uncooked ramen/instant noodles, basically a big tangle of polymer chains which act like a sponge.
Now, consider what happens when you wash that plastic with a cocktail of chemicals in your dishwasher...
Obviously very hard/dense plastics (melamine comes to mind) are less prone to this
The article doesn't seem to have immediate actionable recommendation, and is mainly a brick in a wall that can lead (or not) to better design decisions.
One unclear point for example is what happens with the deposited toxins, how hard is it to clean them? are they transferred by touch?
Well, it's a classic research paper. They're essentially only supposed to report findings.
If you live in a house with central HVAC, a decent, regularly replaced filter will help a lot (make sure to only use full blown HEPPA filters if your furnace supports it otherwise you'll have all sorts of airflow issues). Otherwise you can buy air purifiers. The study measured smoke (cigarette and wildfire) as well as insecticides, so minimizing exposure to both is probably the easiest first step (not smoking inside is easy, but wildfire depends on how porous your house is).
The study is about VOCs. You’ll want a carbon filter, as even a HEPA filter won’t do much.
Also, don’t put a HEPA filler in your HVAC return — not only is it unhelpful overkill, it will have excessive static pressure drop, thus wasting power, increasing noise, reducing airflow, and potentially damaging the blower. Use an appropriate filter in the MERV 13-16 range.
Carbon filters in air purifiers are a pain. They do work, but due to their smaller volumes they tend to get full quite fast and require frequent replacements.
If you're considering one, make sure to get an air purifies where the carbon filter can be changed independently from the main filter.
Having moved into a home previously owned by a chain smoker ten years prior, I have no problem believing this. We've had to run ozonators in rooms repeatedly to finally get the smell out.
I wonder what the air quality inside a submarine is like, after spending 60 days submerged. How does it smell?
I've toured a '60s era Cold War diesel-electric sub that's been a museum for ~20 years, and it still absolutely reeked of diesel. Combine that with the smell of a couple dozen dudes that haven't showered properly in weeks, and your answer would be not good.
The long-term health outcomes are probably significantly worse for people that served in diesel subs than nuclear because of the constant exposure to fossil fuel volatiles. Just being in there for a 20 minute tour made me feel like I just smoked 20 cigarettes.
Nuclear subs have diesel engines too, so I'm not sure what makes you think it wouldn't be as bad on a nuclear sub.
Isn't this obvious? I don't know, maybe there are some details of this study that are are scientifically useful, but as a news it's pointless?
Yeah, make sure to get a lot of ventilation, but that doesn't require any study. Even without any any pollutants, indoor air will have a bad quality. And your body deals with minor amount of bad stuff just fine.
I think that the crowd on HN tend to enjoy learning, and thus wouldn’t find it pointless to read.
> The findings suggest that regular ventilation alone may be insufficient to remove many indoor contaminants. Physical cleaning activities such as vacuuming, mopping and dusting are necessary to effectively remove compounds with high partition coefficients from surface reservoirs.
Yup. Indoor smoker homes are the worst because cleaning alone is often not enough. Cheap landlords just slap a coat of paint on to hide the visible stain, better landlords use nicotine blocker paint that's pretty expensive... but that's only good for moderate smoke. Decent ones run a few ozone generators for a few weeks while no one and no thing is inside, with the added danger that the decomposition products are toxic on their own and the ozone might damage the electrical wiring.
The only actually reasonably safe way to deal with a heavily smoke laden home is to rip out everything where the smoke has seeped into. For the Americans here, that may mean a complete teardown as the cardboard, insulation and even framing wood will be soaked in smoke residue; Europeans have it a bit better because for us, it's usually enough to remove the plaster but leave the brick/concrete walls alone.
Homes that have been affected by fire are often written off for the same reason, even if the fire itself didn't blaze in the home (say, a lower apartment burned off). The smoke seeps everywhere, especially in older buildings where doors aren't airtight or you got bathroom/kitchen exhaust vents without backflow prevention, and fire smoke is orders of magnitude worse in its effect than cigarette smoke - cigarettes are at least plant based materials, household fire smoke is riddled with stuff like dioxine (from plastics) and other highly toxic combustion products.
This is also one of the saddest aspects of retro computing.
Most listings fail to mention whether previous owners were smokers, and most sellers either aren't sensitive to and/or haven't experienced the off-gassing that occurs once devices warm up through actual use.
So this is actually the main reason I'm thrilled about the MiSTer project and the growing number and variety of FPGA-based clones being released today.
I picked up a second hand gaming PC once: 9 months later our entire downstairs floor was still noticeably smelling of their fabric softener despite frequent airings. They’re like sponges.
And some things like arcade machines, you often can't even get them in "no smoker" conditions as they've been installed in arcades, pubs and other venues where a lot of the attendees smoke.
This sounds similar to what happens in cars that have been smoked in, but there are even more soft surfaces, nooks and crannies in a car.
Smaller space, but easier to get fresh air into.
Cars are easier to remediate. The textiles can all be washed with powerful solvents and plastic doesn’t soak up too much smoke.
Brings back memories of how much the old people I know would open every door and window to let in "fresh air".
Sometimes old heads...
newsflash: permeable materials are permeable
Not really good news for my OCD.
Sounds like good news. The sponges take harmful chemicals out of our environment.
Not good news, it's just better to know, than to not know. These sponges don't take chemicals out of our environment, they trap it and slowly release it where we would need cleanness. These chemicals would have gone away a long time ago, but the sponges kept them there.
Additionally why this is not good news, these materials were not supposed to be sponges to begin with. So, it's like discovering a bad side effect. Again, better to know than to not know, but it's not what one would call good news.
...to then re-release them gradually over the next days and months. So, no.
Then you need a better sponge.
Yes, they are bad sponges, that's the issue, both that they are sponges and that they are bad at it.