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).

CO₂ levels during a couple of days, peaking 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?

enter image description here

  • 21
    What kind of device are you using to determine the carbon dioxide (CO2) concentration of 1600 ppm? Are you sure this is accurate? Does the measured level change with time of day? – Jim Stewart Aug 20 at 20:33
  • 6
    Measure the CO2 outside the bedroom. If much lower, use a fan to cycle the bedroom air. If similar levels of CO2, then you might have a leaky appliance. Until you figure this out, open a window on both sides of your home. Your health is more important than air conditioning. – John Hanley Aug 21 at 12:32
  • 1
    @JohnHanley, that's a good idea to measure it outside. Will do that for testing, but I can already guess that it is lower outside because when I open the window, the concentration of CO2 decreases considerably. The Fick's laws are also on my side. I also have a fan running, so it forces the CO2 to go out. – Physther Aug 21 at 14:43
  • 1
    @Agent_L, at 20 ( 8PM) I enter the room to watch something before sleeping. Waking up at 7 and opening the door. – Physther Aug 21 at 14:44
  • 3
    Where is this sensor physically located relative to you while you're sleeping? If it's on a table next to the bed and you're facing it, you might be skewing the numbers by breathing directly onto it. The drop-off before you wake up could then be explained by you rolling over and facing away from the sensor. Move the sensor around the room and see if the numbers change. – bta Aug 21 at 21:56
up vote 22 down vote accepted

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.

  • 1
    It would also be useful to transfer the humidity from the incoming air to the outgoing air; can that be done as well? – Daniel Griscom Aug 20 at 19:31
  • 3
    @DanielGriscom there are variants which do, yes. – Harper Aug 20 at 20:02
  • 1
    Having a small make up air source can really make the air in your home better + – Ed Beal Aug 20 at 20:35
  • 5
    Everyone always ignores the V. With today's hermetically sealed houses, you need a fresh air intake even if you don't get an HRV. – Mazura Aug 21 at 0:30
  • @DanielGriscom Rotary recuperators reclaim both heat and humidity. Also called "thermal wheel". – Agent_L Aug 21 at 14:25

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.

  • 2
    This answer is especially correct if you consider the new graph: unless the OP goes to bed at 8PM and gets up at 5AM, a faulty gas cooker seems more likely. – Sanchises Aug 21 at 12:29
  • 11
    I vote for a highly inaccurate CO2 meter. Get that verified first – Carl Witthoft Aug 21 at 17:25
  • 3
    @CarlWitthoft, I don't think the calibration is a problem. I'm pretty sure the values are in that range. The device can also measure PM2.5, which I checked on an air purifier. It shows very good values. I know there are two different sensors but I trust it's a good instrument and it's new (close to calibration time). Besides, I feel very tired at night and I wake up with headaches when the window is closed. With open window, I feel fresh. Either way, the question is how to get rid of CO2 with or without this device. – Physther Aug 21 at 19:35
  • 5
    @jkf, 1600 ppm is "you want to fix it"-high, but it's not dangerous: you could probably go your whole life breathing that with nothing worse than the occasional headache. As a point of comparison, OSHA and NIOSH state that long-term exposure should be kept below 10,000 ppm, while ACGIA recommends keeping exposure below 5000 ppm. The "immediately dangerous" exposure level is somewhere around 30,000-40,000 ppm. – Mark Aug 21 at 23:35
  • 5
    "That's a really high CO₂ level." [citation needed] – Mazura Aug 22 at 0:06

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.
  • 1
    The 3rd point makes a lot of sense and will surely support the idea of me being the source. Will make the calculations soon. Thank you for the suggestion! – Physther Aug 21 at 15:12

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.

  • 6
    This is terrible advice. Plants do not absorb CO2 during the night (they actually add to the problem). Without light there is no way they could do photosynthesis, but being living organisms they need energy to survive. This energy can only come from oxygen in that case. – Damon Aug 21 at 13:09
  • @Damon good point -- plants breathe at night emitting CO2, i.e. they "burn" carbon they have collected from the CO2 when there was light. The net balance for a growing plant is still that it absorbs CO2, but it does that during the day. I once wrote an answer about that on SE biology ... – Peter A. Schneider Aug 21 at 16:27
  • 1
    You could make a grow-room in a closet so the plants are on cycle where they get lamp light at night and they are in the dark during the day. – Arluin Aug 21 at 18:17
  • 2
    @Arluin if USA-based, that's a recipe for a visit from the DEA. – GalacticCowboy Aug 21 at 19:16
  • 3
    @GalacticCowboy: Good. They need a talking-to. – Joshua Aug 21 at 19:28

Your Answer

 
discard

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.