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Comment by Booktrope | Hacker News Reader

The effect mentioned in this article is certainly not suffocation. 2000 ppm of CO2 is about 0.2% of the air, and doesn't signficantly reduce oxygen levels. It's a real problem, but calling it suffocation is pretty dumb.

This is possibly even a more serious problem in tightly weatherized bedrooms. I was in a rehabbed house tightly weatherized by the contractor (to meet a typical building code). It had radiant heat. When my wife and I sat in the bedroom for 1 hour, a calibrated CO2 sensor showed levels rising to 1600 ppm. (Humans put out lots of CO2). Sleeping 6 - 8 hours in that environment is very likely to cause cognitive impairment the next day. So if you're in a "tight" house, make sure to sleep with the windows open!

Raising the question of course, of why then tightly weatherize the house? Well, so we can say, we're being environmentally responsible, of course!

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https://www.osha.gov/dts/hib/hib_data/hib19960605.html

10% (100000 ppm) concentrations can cause unconsciousness or death even if you have enough oxygen.

It is because we don’t only need to get oxygen from air but also to exhale CO2 as waste. And the higher CO2 partial pressure is the harder it is to get rid of it. Eventually killing us.

> So if you're in a "tight" house, make sure to sleep with the windows open!

The right answer is to switch on your heat-recuperating ventilation.

Or get yourself some sansevieria trifasciata plants. Depending on the size of your bedroom, 3-4 should so it (about 1 per 100 square feet of room). They'll convert CO2 to O2 all night - and clean the air a bit as well. They are also easy to maintain.

How exactly do they do that without sunlight?

Also, just how big are American bedrooms? Mine is 172 sqf and I consider it a big one.

They use of a different mechanism to power it by delay. They use a second CO2 fixation pathway known as Crassulacean Acid Metabolism (CAM). Basically they "store" the energy by day, then open up at night and to their thing. Only 5-6% of plants do it this way and, IIRC, almost all of those are succulents or desert plants. This pathway helps preserve water.

https://en.wikipedia.org/wiki/Crassulacean_acid_metabolism is a decent introduction to it.

Also, most "kid" bedrooms are around 10x10 or so, but some master bedrooms can be rather ... large. I said 3-4 to cover both not being the only one in there and the size of the plants. The tests are done on or projected to full-size mature plants, but if you go to the store and buy them they are rarely full size. They'll range from 6-8" babies to about 1/3-1/2 in size (1-2'). For the "full effect" from the reports they size based on a 4' tall plant.

or ERV.

The right answer is not to have such a tight house.

Instead of spending resources to tighten it, then spending more resources to install a compensating appliance.

Is that accurate though? So I live in recent new construction, and run the house fan for long periods of time/overnight, and the power bills are still the lowest I’ve experienced. Fans take very little power to run, compared to burning gas/running ac to achieve desired temperature...

A heat exchanger will allow you to circulate the air without losing most of the heat.

I wouldn’t be surprised if by 2100 we have rooms that maintain low CO2 PPM indoors because outdoors would be 1000+

And only a select few can afford to keep it going all the time.

Well the people who make a living projecting high CO2 levels would be surprised, since that is about 50% higher than their recent highest projections. Some older predictions had the levels in 2100 up to 800ppm, but the IPCC has been revising them downward for quite some time now. This is in part because we've had them for long enough to see they haven't been accurate, and because the "worst case" ones don't use any theory they just calculated a straight based on the highest rate they find. These predictions have consistently been higher than actual data. So the likelihood that we'd hit 1000ppm by 2100 would mean they'd have to have predicted around 1100-1200 ppm by then, but their worst case is around 800ppm. Which, based on their historical performance would indicate the worst case is more akin to 600-700.

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