Carbon Dioxide levels inside cabin while using HVAC in Auto mode

[ElGuano]

I have a bunch of CO2 monitors, have never tried to measure in the car before, but sitting in a home office for 15 minutes without a window open will quickly spike CO2 levels above 1500ppm. I wouldn't be surprised at all if a car cabin with recirc on spikes much higher.

But if you select recirc mode, what exactly would you expect?

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[rhumbliner]

There was an episode of CarTalk many years ago about this very subject. A women called in asking if she could pass out from lack of oxygen while driving with the recirc on. She claimed her husband told her to always drive with a window cracked. After Click & Clack stopped laughing they told her, in plain English, that her husband was an idiot.

 

[Dark-Fx]

Sounds like someone just has too much time and equipment on their hands. Maybe just set the mode to always pull in outside air or open a window and not worry about it

3.6 roentgens. Not great, not terrible.

 

[Dark-Fx]

There was an episode of CarTalk many years ago about this very subject. A women called in asking if she could pass out from lack of oxygen while driving with the recirc on. She claimed her husband told her to always drive with a window cracked. After Click & Clack stopped laughing they told her, in plain English, that her husband was an idiot.

CO2 is a legitimate concern for the DIY teardrop community. They design their coffins to seal so well that they can end up dying overnight if they don't wake up from the lack of fresh-air introduction. Which, if you don't, you had other health issues to begin with.

 

[Dave Cundiff]

There was an episode of CarTalk many years ago about this very subject. A women called in asking if she could pass out from lack of oxygen while driving with the recirc on. She claimed her husband told her to always drive with a window cracked. After Click & Clack stopped laughing they told her, in plain English, that her husband was an idiot.

Oxygen and carbon dioxide are separate issues.

As I recall, air is 21% oxygen. It takes a LOT of oxygen consumption to decrease that percentage by enough to matter. Even the air we breathe OUT has enough oxygen in it (maybe 16%?) so that CPR works!

Outdoor air is about 0.04% carbon dioxide. It doesn't take much CO2 production to increase that percentage significantly. Since carbon dioxide functions as a weak acid in our bodies (dissociating in water to hydrogen ion and bicarbonate ion), and since acid-base balance is crucial to our metabolism, "excess carbon dioxide" is at least potentially concerning while "inadequate oxygen" is not.

In CO2 environments of 3000 ppm, most of us would just breathe a little faster in order to keep a steady blood level of carbon dioxide/bicarbonate. Most of us wouldn't notice the difference at all. Some might be more sensitive, and might notice an effect. So the original report didn't show any levels that I would find urgently concerning.

Still, it would be a classy thing (and probably pretty easy to program) if Rivian addressed mandatory-minimum ventilation via a future OTA.

Best to all!

 

[Singletracker]

I usually crack a rear window a bit to aid circulation. If the windows are closed and cabin is sealed, even setting the HVAC to use outside air will minimize the air flow. If you’re cramming air into a sealed space, you need to make room for it. A little window venting does wonders for the air flow. Do that and quit breathing (exhaling CO2) and problem solved.

 

[Eeyore]

Maybe keep it on recirculate for the first several min if the cab is really hot, then switch to "normal" once the cab cools down. Isn't that what most folks do anyway?

I do the opposite. Usually the outside air is cooler than the inside of the truck when I get it. I want to blow out the hot air while the HVAC starts up. Once it's producing cold air, I put it on recirc.

 

[Eeyore]

the DIY teardrop community.

I just realized that you are talking about camping trailers.

 

[madhat]

I usually crack a rear window a bit to aid circulation. If the windows are closed and cabin is sealed, even setting the HVAC to use outside air will minimize the air flow. If you’re cramming air into a sealed space, you need to make room for it. A little window venting does wonders for the air flow. Do that and quit breathing (exhaling CO2) and problem solved.

Pretty sure Rivians have pressure relief flaps (usually in doors) that all cars have. It's not 100% outside air, maybe 10%, but there is still fresh air coming in with the windows closed.

 

[tjrivian]

While I am not particularly concerned with these elevated CO2 levels, I think the article does do a great job of pointing out yet another flaw in Rivian's auto-climate control mode. Rivian vehicles are significantly behind other manufacturers auto modes when it comes to both keeping a comfortable temperature AND good fresh air quality. Hopefully articles like these will convince Rivian to invest to make these features better in the future.

 

[Donald Stanfield]

I was wondering this myself after a long road trip on recirculating air. I got a headache and was dizzy. I switched to fresh air and felt better. I don't think this is a Rivian issue though, any car with a decent cabin seal is going to have this problem. After this I might change my behavior to turn off recirculating air.

 

[josh0]

I am shocked an appalled that a CO2 scrubber is not standard equipment on these vehicles!

 

[Laserboy1054]

I just realized that you are talking about camping trailers.

Thanks for saving me a google. I thought it was a goth sex thing. Hmmm...now that I think about it...

 

[MountainBikeDude]

So, one thing someone brought up a couple weeks ago on this same subject was that even in manual mode, the HVAC will still kick back and forth between external air and recirculating periodically.

I didn't believe the post at first, but started to notice the same behavior in mine despite not being in Auto. Whether or not this is a bug, or an intentional efficiency move on Rivian's part, it is somewhat worth making not of, especially if it's not intentional.

 

[beatle]

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