CO2 and Indoor Air Quality, school me please

[Poindexter]

I have a CO2 problem. Typically my clean outdoor air carries 200-300 ppm CO2. When I am home and exhaling CO2, I need to run my HRV 40 minutes per hour. At that setting, my indoor CO2 usually runs in the 600s of CO2 ppm.

Today, with hazardous outdoor air quality I am seeing 700s ppm CO2 indoors.

Here is three pics, I'll add discussion in the next post.

 

[Poindexter]

Fundamentally, I am running everything I got at full throttle.

The sensor at "NCore" run by the EPA (and closest to my home) doesn't publish CO2. I don't know if they measure CO2.

Currently two wildfires burning within 30 miles of town. There are a couple directions the wind "could" blow from to relieve the city of wildfire smoke.

The intake filter on the HRV captures 50-100mcg/m3 of PM2.5. The box fan on the floor with one MERV 13 taped to the back draws 0.5 amps continuous. The fridge sized cabinet with 6 of MERV13 in it draws 0.6 amps continuous. My standalone dehumidifier is drawing 5.5 amps on about a 50% duty cycle to maintain 40%RH.

I could turn up the HRV to continuous to flush out more CO2, but my particle counts will start going up.

So I am looking to add some kind of CO2 capture to my IAQ suite.

 

[Poindexter]

Before you start selling me on house plants, please understand that so far this summer I have killed two dill, 2 thyme, one sage, 2 oregano and a rosemary. These were all on my kitchen counter next to my cutting board.

NASA did find that enough plants can scrub CO2 from human habitation, but they needed 10-1000 plants per square meter of floor.

https://en.wikipedia.org/wiki/NASA_Clean_Air_Study

I hear spider plants are tough and hard to kill. I will get one to see if that is true.

 

[Poindexter]

Well fiddlesticks. I have turned the HRV up to continuous.

 

[stoveliker]

I think you don't need to aim for outdoor CO2 levels indoors.

 

[Poindexter]

@stoveliker , in this thread https://www.hearth.com/talk/threads...d-indoor-air-quality-hearth-com-style.198427/ comma, I busted out my google-fu for this post: https://www.hearth.com/talk/threads...y-hearth-com-style.198427/page-2#post-2675304

In my preference less CO2 is better, some is inevitable. Given my previous findings as linked above, my comfort zone is under 700ppm. Ambient outdoor CO2 in Fairbanks, with no wildfire activity seems to run 200-300 ppm.

I think of CO2 <700ppm as the green zone. 700-800ppm, single yellow. 800-1000 ppm double yellow, over 1000ppm is the well accepted red zone.

Like PM2.5 this is an airborne pollutant I would rather keep managed in the green zone rather than try to come up with something from scratch when I am already in the red zone.

I did also have this observation in a thread about HRV systems. Running the indoor CO2 up to 1660ppm (measured) when my first CO2 detector came in the mail got my undivided attention. I had been running the HRV one hour per day as instructed by the landlord. I had been grumpy and not sleeping good and constant headaches for more than a week. Once I got the place aired out and the CO2 level under control all that cleared up save for my baseline cantankerousness.

 

[stoveliker]

Yes but all the URLs there basically say <800 is okay, recommended etc.

 

[Poindexter]

I am not sure which sensor was used to come up with the PM2.5 count of 1160 mcg/m3 this morning, but it is believable.

I am kinda leaning towards adding capacity to my particle filters for days like these. With the toolbox I have just pumping out exhaled CO2 and dealing with incoming particles seems like the path of least resistance.

I am very open to points of view from folks with different skillsets.

 

[EbS-P]

I regularly see 900 ppm CO2 measurements on my cheap meter. I’d like it to be lower but I don’t have a good way yet to bring in filtered air. In your case I see your elevated CO2 levels as not typical but how many days a year will you see them? Sounds like you. Need a co2 scrubber. How about supplemental oxygen for really bad days. How much would that cost?

 

[zrock]

not something i ever check for and im far from knowledgeable on this subject, but first thing that came to mind is what inside your home is increasing the level, and why is your landlord telling you how to run it? First thing that comes to mind is something in the home.

 

[begreen]

I am not sure which sensor was used to come up with the PM2.5 count of 1160 mcg/m3 this morning, but it is believable.

I am kinda leaning towards adding capacity to my particle filters for days like these. With the toolbox I have just pumping out exhaled CO2 and dealing with incoming particles seems like the path of least resistance.

I am very open to points of view from folks with different skillsets.

View attachment 328129

And I thought New Dehli with an over 600 reading was bad. That's awful.

 

[Poindexter]

And I thought New Dehli with an over 600 reading was bad. That's awful.

I am noticing the wildfire smoke here this summer is not evenly distributed. There is an over all minimum, and perhaps a bit of an average, but there are also some remarkably thick tendrils slithering around in the murk.

To me 1166 mcg/m3 local one one sensor is believable, but I doubt the sensor of the homeowner is actually calibrated to read accurately at that high of a concentration.

It is awful.

 

[EbS-P]

I’ve been thinking more. They burn the pine plantations here. We will get ash fallout from it. Max we have 4-5 days a year. Indoor CO2 below 1000 ppm might make for an uncomfortable 5 days for me but probably not unhealthy.

Parts of the world will undoubtedly see many more than 5 days. The answer it’s filtered outside air. At multiple stage filtration may be needed. Have you read anything about clean room design for semiconductor manufacturing? Probably some decent information to be gained.

 

[peakbagger]

FWIW,I looked into CO2 scrubbers for an industrial HVAC issue about 20 years ago. It was sealed insulated small room for a process control computer. Operation employees tended to hang out in their during their shifts as it could be brutal outside the room especially in summer. There was gasketed stainless steel door to access the room. The outside environment was hot wet and nasty. The computer needed clean air cool air but its location precluded bringing in outside air to pressurize the room. The room had a AC unit that just recirculated air around and round. The only fresh air was leakage and when the door opened. It smelled like a locker room inside and there was valid concern about air quality including CO2. I was asked to find a CO2 scrubber for the room and I never found one that met the requirements. There were amine based units but way out of the budget. The management decision was to ignore it and ban workers from hanging out in it.

At the pulp mill, there were a couple of rooms for Distributed Control Systems with walls of racks of local I/O panels and the main processors, the atmosphere even outside the buildings was corrosive and unless the rooms were supplied treated air, the electronics didnt last long. We installed deep bed scrubbers which usually were activated carbon based with some potassium permanganate added to it. The air volume of the room was circulated through the beds continuously with a small outside vent upstream of the carbon bed to pressurize the space. If the rooms were well sealed, the doors were kept shut and the system maintained they worked well but it was a bear to retrofit the systems to existing rooms. The filter media had to be changed about every 3 months. The media supplier supplied special test coupons that consisted of strips of copper, silver and gold that were placed in equipment cabinets and they could send them out to the lab and determine the extent of corrosion and link that the media life.

 

[begreen]

I am noticing the wildfire smoke here this summer is not evenly distributed. There is an over all minimum, and perhaps a bit of an average, but there are also some remarkably thick tendrils slithering around in the murk.

To me 1166 mcg/m3 local one one sensor is believable, but I doubt the sensor of the homeowner is actually calibrated to read accurately at that high of a concentration.

It is awful.

Unfortunately, this is going to get worse. I've read that the temperature swings and extremes will be felt in the arctic regions the most. The major loss of arctic sea ice in June 2024 is most disturbing. So are the expected and unexpected effects of permafrost melt. 2023 was a record breaking year for global temperatures and 2024 is already on track to beat that record easily.