Best way to remove CO2 in a bedroom?
I know that CO2 sequestration/capture is imperfect and expensive; however, I was wondering if there is a doable way to remove CO2 in a bedroom at night, to improve air quality why we sleep?
Not being snarky, but a window is one of the best options. Air conditioners can often be your worst option, as the air is recirculated more aggressively. We use a window fan that has multiple settings: circulate, ingress, egress. I find that no matter what setting you use, air is recirculated significantly well. On hot days, the fan is set on egress. This seems to do a really great job of removing excess CO2 while not bringing that much hot air into the house. We have a window fan running in the kitchen for the bulk of the year. We also find that simply cracking the windows in the winter makes a large and measurable difference in CO2, but not with heat.
Ventilation is usually the best way. Even when there is a temperature differential between the outside and inside, it's more economical to heat up / cool down in the new air than trying to scrub CO2 [1]
If you have an air quality concern, you can start by installing an indoor air quality monitor with a CO2 sensor.
[1] https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber
There is no small scale human comparable in room CO2 removal bio/tech. Human breath will increase CO2 in a closed room on the order of many hundreds of ppm over hours, while even "superplants" like those in an Algen Air will decrease it at best on the order of low tens. We need improvements of two orders of magnitude to have room scale impact. So the only answer is "fresh" air ventilation.
Turning on a bathroom vent fan is remarkably effective. Based on the CO2 monitor in my basement utility room, turning on a bathroom vent fan in the upstairs lowers the CO2 in the entire house within a few hours.
An energy recovery ventilator would be ideal, though, as it wares much less energy while still lowering your CO2 levels.
It would be awesome if there were a way to actually capture and sequester in-home CO2, so that your in-home number could be lower than the outdoors. But I’ve never heard of such a thing.
For the kind of technology available to us, it could cost up to $100 a day to buy enough "soda lime" to filter out the CO2. You'd want the "color changing" type of product. You would also need HEPA filters to ensure the powder was not getting in the air. Temperature sensors would also be needed to ensure it wasn't releasing so much heat that it causes a fire.
The algae route is cheaper, but needs a lot of algae.
Energy recovery ventilator. It will exchange indoor air with outdoor air while maintaining indoor heat and humidity. Unfortunately small window mounted models are hard to come by. Most are whole-home systems.
Do you have a CO2 monitor? I bought one during Covid to monitor the classroom I teach in. I was surprised by how bad it got: well over 1000 ppm.
When I brought the monitor home, I was surprised all over again by 1000+ ppm levels with just a couple of people and a cat. All the efforts to seal the house for energy efficiency were in direct opposition to advice to lower CO2 levels. The only reasonably effective solution that isn't absurdly expensive is to open the windows a little. All the time. You pay more on heating and cooling, but.. there is no alternative.
The good news is that it gives you a reason to leave the drafty window air conditioners installed all winter long.
And house plants have negligible impact on the levels. Keep plants for the aesthetic, but they aren't going to solve the problem.
I've found an in-window fan unit (blowing outward) is very effective at keeping CO2 levels down. Noisy, though.
Before that, overnight CO2 levels exceeded 2,600ppm. Now
around 700 or so. Can go lower if I crank the fan up.
Now I have the new problem of poor thermal regulation. My window is directly above my HVAC duct, so cool air goes straight from my air conditioner through the fan and out the window.
I plan to wire up a microcontroller to turn the window fan on and off based on both CO2 levels and A/C activity, but I'm not really happy with the the setup. Too hacky, too much noise, and I need to seal the window screen better to keep bugs out.
I've tried just keeping a window open, with no fan, but my CO2 sensor indicated it wasn't super effective. Plus you have to make sure you close the window when it rains otherwise muggy air fills the bedroom.
It’s typical for bedrooms to have a ACH (Air Changes per Hour) rate of between 0.35 and 1
So the CO2 is removed regularly.
Is there evidence that CO2 levels in the air matter to human health? Humans can tolerate a fairly wide range of blood CO2 levels. We have a buffer system in our blood, and we can use our kidneys to pick up the slack when ventilation (via the lungs) is suboptimal.
Depends on your climate/weather, local noise/crime, and construction of your house.
Opening a window can be an option. So can an open bedroom door.
The best option to me is to just leave your air handler fan set to "on" rather than "auto". Of course you need forced air for this. My house is relatively newer and moderately sized. It still seems to keep the whole house CO2 levels like 50-100ppm over outdoor levels. The bonus here if you're looking for "air quality" and nor just CO2 is that your air handler filter should catch many particulates (although most aren't capable of high merv ratings, it still seems to help).
We leave our bedroom door open whilst we sleep which pretty much solves the issue. Leaving the ensuite bathroom door open also helps but not quite as much as the door to the hallway.
In the UK, 'trickle vents' are mandated in new build houses. They're little vents placed above external facing windows and doors that can be opened and somewhat closed. The goal is to allow moisture to escape to prevent mould but they also obviously allow constant airflow. They don't really allow bugs to get in either.
video: https://www.youtube.com/watch?v=6_2SdLEbHcM
Buy a CO2 monitor.
Then keep a window open enough to keep the air fresh.
I find a few centimeters of gap is all that's needed.
Periodically open your windows wide. If the CO2 quickly builds up though, you could perhaps just leave some windows cracked open. Or you should get some proper ventilation installed. If CO2 is high then other pollutants are likely also high.
I have spent a considerable about of time on this question: and it really seems there is no practical way to remove it. You can let it out by ventilating, but that’s about it.
This realization has made me quite anxious about the Keeling curve.
Mechanical ventilation with heat recovery is a common term (MVHR). Basically a fan but it tries to recover the heat lost in winter. Usually comes as a whole house system but there are some that do single rooms.
I may be missing something (perhaps OP doesn't have windows?) but I open my windows in all the rooms a couple of times per day (in the morning and usually in the afternoon-evening). Isn't that enough?
VMC in general, for energy usage reasons (meaning opening the windows cause too {cold,hot} air inside, open windows (with eventual mosquito net if needed) when external climate allow that.
Opening the window should help, unless the outside air is highly polluted. One can also install a fan that either vents air out of the room to the outside or draws fresh inwatds.
While not directly related to CO2 removal, for air quality, especially if you live in an urban area, adding an air purifier is very useful.
Sleep with the door open, if opening a window isn't an option. At least you won't be hotboxing yourself with CO2 in a tiny area
When using a CO2 sensor in my room, opening a window was very noticeable as a drop in CO2 on the graph.
You could try to use plants and a growing lamp for them to do photosynthesis.
Have a fresh air intake installed on your HVAC system.
What’s the best device to measure CO2 in a bedroom?
I want to experience pre-industrial co2 levels
This is a bit of a nonsense question. The CO2 diffuses away rather quickly and there is no reason to worry about this.