How to get rid of CO₂ in a house with A/C in hot summer?

Question

Recently, I've been measuring the CO₂ concentration during multiple nights and the levels in the bedroom where I sleep are very high and unhealthy (over 1600 ppm).

_{I use an AirVisual monitor, which is high precision and catches the trends. I opened the window last night, and that's why the CO₂ is lower. But on all the other days, it's over 1400-1600 ppm.}

I get a high concentration only when I'm sleeping, so I assume that the CO₂ comes from me. Since the windows are shut and the door closed, the CO₂ gets trapped.

The problem is that during the summer, the temperatures outdoor are over 95 F (35 C) with high humidity, and I have the airconditioning running inside. If I open the window, the heat comes in very fast and then the AC has to do extra work, which means waste of money and resources. And it's the same situation during the night.

How do I get rid of CO₂ inside the house without opening the windows when the weather is hot?

EDIT: After reading all the great suggestions, I have tried a new measurement with the device far away from my bed, so it will not be affected by my breath. I also checked for timers and couldn't find any. Last night I closed the window and the door at around 11 PM and the concentration started to slowly increase. During the night, the CO2 levels increased significantly (see graph below). In the morning, I opened the window and it slowly started decreasing. I have no doubt that there is a lot of CO2 in the room. So my question stands. How to get rid of CO2 or any other gases/vapors for that matter, in a hot, humid climate. Is HRV the only solution?

Answer 1

You want an high-efficiency heat exchanger.

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

Basically, you pipe in fresh air, but have it cooled before, while you heat out the air that is going out. It's typically installed on central hvac systems.

It needs maintenance to be efficient and it is quite often overlooked by contractors as it's hard to notice when it's not working.

Answer 2

That's a really high CO₂ level. You need to figure out what is causing it and fix that, it's not normal.

Gas fired appliances with leaky vents are the most likely suspects — hot water heater, dryer? (Probably not your furnace, since its summer!)

In the meantime I would seriously open some windows and suck it up, that's dangerously high if accurate.

Answer 3

What type of air condition are you using? Some only cool the air inside, while others use fresh air from outside. In a cafe or club there are norms about how much fresh air the air condition must put inside during a given period of time.

I would suggest the following:

1. measure the CO₂ concentration outside to compare it with your inside CO₂ concentrations.
2. Measure CO₂ concentration on a Sunday while you stay at home. Does it increase the same amount?
3. Try to calculate how much O₂ you turn to CO₂ while you sleep and make an estimate of how large the CO₂ concentration should be after one night. If it is much higher than it could be just by your breathing, search for other things that may increase CO₂ in your room.

Answer 4

Plants respire throughout the day, producing both O² and CO². They produce much more oxygen than CO² though. It is a good idea to have plants to help with air, but they don't produce enough to make a huge difference. People intake approximately 750L of oxygen per day. We exhale approximately 0.02 cubic meters of CO² per hour. A plant, on average, produces approximately 22L of oxygen per day. It would take a lot of plants to change your room's exchange. That doesn't mean it is a bad idea though. Everything helps. Specific plants exchange better than others, and some help to remove harmful pollutants from the air. Do not fall victim to the myth that plants exchange CO² only at night and that they come even close to an even exchange. They exchange far more oxygen and do help.

Answer 5

I have asthma and an 80% collapsed windpipe. With CO2 levels even within a good range (less than 600 ppm) I become short of breath. I had an erv system(energy recovery ventilation)system installed. Can’t use that during fire season! It hasn’t helped at all and the installers haven’t been helpful in figuring out why an open window does a better job. When I use it Particulate matter increases and opening windows does a better job of lowering CO2. The best idea I’ve found is to reverse a powerful fan out of the window to pull CO2 from the room. In minutes I can reduce the level but I can only rely on this method in the spring and fall unfortunately.

Answer 6

Snake plants might help - they intake Carbon Dioxide during the night and need very little light and water. Read the below research papers:

https://www.ias.ac.in/article/fulltext/sadh/048/0049

https://ntrs.nasa.gov/api/citations/19930073077/downloads/19930073077.pdf

Answer 7

Yeah. CO2 is nuts. I just bought a Carbon Hepa Air Purifier and the minute I turn it off triple fan, the highest setting; an Air Monitor alarm goes off in the bedroom, even though I'm not in there. Basically; the smaller the apartment, the harder you work/breathe/have big lungs and the better sealed it is; the worse it ramps. Well; placed in the centre of the apartment, in the middle of the floor on full 24/7 (it only uses 25 Watts or so); the alarm is off and it's down to about 450ppm. Gonna stick it on a RCD 'cos it's working fairly hard (for when I go out). All's I did was turn it down to No. 2 fan when I went out and I came back to alarms screaming. So; I've solved the problem. I've got more energy, feel more positive and my memory is coming back that I didn't even know I'd lost? I feel a bit trippy and spaced-out but I'm sure I'll get used to it. I wouldn't want to clean too far below 400 because we are designed to absorb/dissolve a certain amount of CO2. I'm not planning on "doing a Michael Jackson" with his pure Oxygen sleep chamber anytime soon. God knows what damage years of sleeping in excessive CO2 has done to me poor, wee brain; but I believe it's healing GREAT! Think CO2 makes us irritable, even spiteful? Damn strangest thing it resolving. The last week has been like watching a movie of irritability passing from me that doesn't amount to anything at all. I wasn't irritable before but it is defo. perfecting my nerves. Hope this helps.

Answer 8

Contrary to popular belief, I think there is too much hysteria over CO2 levels. In some countries, people sleep with bedsheets and duvets over their heads. I can assure you that they do not die, do not go mad and their brain does not suffer.

Sure there is a limit where CO2 is dangerous, but I do no think that level is as low as prescribed by the UN.

Having said that, I have a Mitsubishi HRV system called Lossnay. It feeds my 3 heat pump systems with air. This is because I have a almost sealed house to improve heating efficiency.

I would suggest that you look for something similar.

Answer 9

You can also try this: Get some plants in places where there's high co2 concentration. If there's no sun, then use plants which are good in that situation.