Suffocation risk
user-7573980
| Posted in Mechanicals on
Hi everyone, this is kind of a dumb question but part of me feels weird about a house that has to rely on mechanical ventilation in the event of prolonged power outages…
Could a family conceivably suffocate in a house with 0.01 ACH (or 0.0) where the power went out in the night and they breathed up all the oxygen?
Not sure how to calculate these things, but imagine a 1500 sf house with 8’ ceilings, and 4 people breathing.
Happy Monday! Lol
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Replies
I don't know but I doubt it. I have never heard of anybody suffocating in a house. Probably they would notice the air getting stuffy long before there was any serious danger.
It would be awful hard and expensive to create a house with a 0.01 ACH.
Well, I just wrote a long post doing the math on this, but wordpress apparently doesn't like it and says I've been blocked, so you get the summary: After 12 hours of light activity, CO2 levels are uncomfortable but not deadly at 5500ppm, and O2 levels are reduced but not dangerously so.
Editors, is there a list anywhere of what gets one "blocked"? I've unsuccessfully tried several times to post my original comment with the math, and I always get a "you've been blocked" message. I'm pretty sure I'm not using any profanities, and I've tried posting without any links too, so I don't know what's going on.
bumped so editor will see this. I'd love to see the math also.
I suspect the risk would be quite low. That said, CO2 levels can climb rather rapidly. On Sunday, I was home alone for most of the day with our HRV turned off and windows closed. At 06h00, CO2 levels had stood at 850 ppm and by 19h00 they had topped 1,700 ― no pets, no scented candles, no combustion appliances; 53-year old, 2,700 sq. ft. Cape Cod, not exactly air-tight.
There have been times when it has exceed 2,500 ppm (in this second chart, it hit 2,880 ppm before I turned the HRV back on).
My understanding of human physiology is that we are quite attuned to the danger of suffocation, and that our body starts to panic with rising CO2 levels, long before the level of O2 gets dangerously low. So it's unlikely you would suffocate in your sleep.
The reason carbon monoxide is so dangerous is that your body doesn't really detect oxygen scarcity so much as the presence of CO2. So if you're breathing a gas with no O2 in it, but no CO2 either your body won't know the difference. It's also the reason high altitude can be dangerous.
You are correct, the body can sense CO2, but not O2 or CO. If you ever breath a very high CO2 atmosphere, your body will give you a "BAD! GET OUT!" feeling. I've had the fun of expieriencing this before with a CO2 fire suppression system.
I don't know if your body would notice a very slow increasing concentration of CO2 though. The slow increase might make you less likely to notice. You'd probably feel weak and have a headache and not necassarily understand the reason why.
Bill