I assume just installing CO2 scrubbers would have no benefit though, since the CO2 level is just a proxy for how much the air is recirculating.
So all the standards and codes are designed around reducing unnecessary ventilation and frankly, there's been very little consideration of the health implications until COVID hit.
On the HVAC side, you want a system with a high CoP and I'd probably be looking at some form of energy recovery on the ventilation side.
I live in a relatively new building in NL, where many of these configurations are applied and on its own it won’t go lower than 21C in winter and 25C in summer. Thick walls, thick anhydrous cement floor layer for insulation (although I think it’s also meant to give the option to implement floor heating), _external_ blinds on the South side.
I simply can’t justify a smart thermostat/radiator valve build, despite my inside nerd constantly whispering I should.
Only downside is the heat exchanger air recirculator: it dries the air terribly in winter. You need a humidifier to avoid getting parched skin and mucosa.
This is the answer! Even more important than insulation is air sealing, so you keep the conditioned air inside.
I've learned an enormous amount about building efficiency from
https://www.greenbuildingadvisor.com/ and https://www.energyvanguard.com/
I installed it, and would never go back to forced air. For some reason, it's not popular on the west coast.
It's so simple, a DIY'er could do the instal.
My energy bill is down, and allergies are better.
(I've noticed every store I have been in has forced HVAC, and I have a weird feeling forced air spread viruses. Plus--most retail stores have old systems. They might have slapped in some high mir filters, but I doubt they help with anything on old leaky systems.
(To those interested in hydronic heating, buy Modern Hydronics, by Stegenthal? I'm too lazy to look up his last name, but his book is used as text books.
- The term hydronic heating.
- That most Americans don't have hydronic heating.
That's so weird, here in France radiators are just ubiquitous.
This is the detachable showerhead thing all over again. How do you people survive like that? You're supposed to be the highest GDP country in the world!
You can also find baseboard heating, but that tends to be electric and have quite expensive operating costs. It's mostly only used in additions and places where you would only heat the space if you were currently in the room.
> This is the detachable showerhead thing all over again.
Uhhh... Everywhere I've lived in the US has had a detachable showerhead, from places built in the 1890s to places built in the 2000s. It's a normal thing for apartment dwellers to buy a nicer showerhead to replace the likely cheap and crappy one that landlord installed and then put the crappy one back before moving out.
You’ll find hydronics in expensive houses that can justify the double expense or in colder climates where the heating benefits are more important than AC.
Also everyplace I’ve lived in the last 25 years has had detachable showerheads.
This contrasts against the more common American method of using hot air to heat a home. I believe air heating is more common in the US because AC systems already require the relevant air ducting, so it's easier to install.
Meanwhile here in NL airconditioning is very rare, and 95% of people use a gas fired water heater and metal radidators in rooms for heat distribution.
He recommended I buy it myself on amazon and linked me to a youtube to install it: https://www.iwaveair.com/products/iwave-r
He said that his company would install it, but they'd overcharge and it is easy for anyone to install themselves. He had one in his house and told me all about it like a sales pitch. I installed one not because of the coronavirus, but because it helps with particulates in the air such as pollen and dander, which absolutely wreck me. I've only had it for a year, but it does seem to be noticeably better allergy-wise.
That's a good thing, because there is no safe/acceptable level of ozone in indoor air:
https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-...
Ionizing can be a great way to remove fine particulate from the air, but it works best when there are charged surfaces for the charged particles to plate-out on. Simply ionizing them in the ductwork means the particles stick to whatever's handy, which may be the ducts, may be the furniture, may be your lungs.
Which is to say, this product uses a lot of the right vocabulary, to describe precisely the wrong engineering.
https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-...
Do read the warning from the EPA.
We are, of course, talking about miniaturizing a Direct Air CO2 capture system, which usually operates at large scale to get efficiency. Replaceable cartridges that are regenerated at a central location may be a better option.
But oxygen concentrators are small and cheap and portable and don’t require much energy to operate.
At 1400ppm CO2, we've turned what, 1000ppm O2 into CO2 (is it 1-1?), or 1% of the atmosphere. Dropping O2 from (Edit: Fixed numbers) 21% to 20%. Or about a 5% reduction in O2 density. Equivalent to approximately 1500 feet of elevation... That's just not that much.
(There's also a long list of papers showing issues with CO2 toxicity at low levels of CO2... I keep intending to write a blog post summarizing them)
1400ppm is 0.14%. Earth's current atmospheric co2 level is around 400ppm, or 0.04%. While the jump from 0.04% to 0.14% might seem significant (3.5x more co2!), it's not.
Submariners survive on 3400 to 11300 ppm co2, or 0.34 to 1.13%:
> Submarine crew are reported to be the major source of CO2 on board submarines (Crawl 2003). Data collected on nine nuclear-powered ballistic missile submarines indicate an average CO2 concentration of 3,500 ppm with a range of 0-10,600 ppm, and data collected on 10 nuclear-powered attack submarines indicate an average CO2 concentration of 4,100 ppm with a range of 300-11,300 ppm (Hagar 2003). [0]
[0] https://www.nap.edu/read/11170/chapter/5
I'd like to emphasize that the average CO2 concentration for submariners is 4,100 ppm or 0.40%, or ten times Earth's current CO2 level.
Oxygen is much more toxic than small amounts of CO2. Pure CO2 will kill you quickly, pure o2 will kill you slowly.
> (There's also a long list of papers showing issues with CO2 toxicity at low levels of CO2... I keep intending to write a blog post summarizing them)
I'm interested.
2) Don’t doctors provide severe COVID patients with pure oxygen? If it’s toxic, why would they do that?
3) How does pure oxygen kill you? What’s the mechanism?
Pure CO2 will knock you out in 4-6 breaths, and cause your expiration in 10-20 minutes. Laboratory animals are routinely euthanized with co2 [0]. Pure O2 will cause your expiration in 4-6 days through the accumulated damage of reactive oxygen species.
[0] "Expose the animals to CO₂ until complete cessation of breathing is observed for a minimum of 2 minutes (a total of approximately 5 to 10 minutes is usually required)" - https://www.bu.edu/researchsupport/compliance/animal-care/wo...
> 2) Don’t doctors provide severe COVID patients with pure oxygen? If it’s toxic, why would they do that?
This is bad medicine. Early 20th century medical investigators figured out best practices for oxygen support, but the insights got forgotten, now they're just in the old papers in the libraries.
> 3) How does pure oxygen kill you? What’s the mechanism?
tl/dr: Hyperventilation.
Oxygen is highly toxic to the cells in the human body, but not generally under standard atmospheric pressure. Breath pure oxygen while >33ft below water and you’ll quickly experience oxygen toxicity, ultimately leading to death. Yes, that’s generally specific to divers, but even pure oxygen at standard atmospheric pressure can have health impacts.
More information: https://en.m.wikipedia.org/wiki/Oxygen_toxicity
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> I'm interested.
Well I don't have a blog post ready to go yet, but I can point you to some papers now.
- This review cites a bunch of papers about health effects in the 1-10k ppm range: https://www.nature.com/articles/s41893-019-0323-1.epdf?refer...
- Table 3 in this paper references a bunch of papers around 10kppm: https://www.researchgate.net/profile/Susan-Rice-3/publicatio...
- These papers show mental effects in the 1-4k ppm range:
https://ehp.niehs.nih.gov/doi/full/10.1289/ehp.1104789
http://www.aretas.ca/sites/default/files/imce_images/Indoor%...
- These two are from nasa about the ISS - which brings it's own complications but otherwise also show mental effects in the above range
https://web.archive.org/web/20190613133240/https://ston.jsc....
As someone pointed out in a reply to another comment in this thread, oxygen is especially toxic 33 feet below the surface of the water (because of higher pressure), but can have toxic effects at the surface too. I don't grok respiration yet, but my understanding is that altitude/pressure is essential for putting the relative N2/O2/CO2 partial pressures into context.
Dry air is ~21% oxygen by volume.
I'm getting the density numbers from here by the way if you want to check the rest of my math: https://www.engineeringtoolbox.com/air-altitude-pressure-d_4...