The nights became colder so we started closing the window during night. This brought the topic of measuring Indoor CO2 again in scope. Motivated by this research, i decided to try and close also the room door it and monitor what happens with CO2 Levels during the night. As you know elevated levels of Carbon Dioxide can result in headaches and bad sleep. You can find an interesting read about this here.
Or bedroom is ~16 m2, part of a 120 m2 apartment and usually we do not close our door. The apartment is free and we do not have lot’s of flowers inside, so the CO2 Level in the evenings is ~800 PPM. On the chart below you can see the changes in CO2 based on the occupancy of the room and whether the doors or windows are shut or open.
While I was expecting it would rise, i was quite surprised to see the rate in which CO2 rises. On the chart below i have estimated it at ~430ppm/h.
Time-Graph of CO2 PPM Level while sleeping in a closed room
What you can clearly see on the chart is how each change in the rooms occupation affects the CO2 Level quite quickly. Also what is astonishing is that we passed 2000 ppm at ~1 am. This is just 2 hours after we went to sleep in a relatively fresh air.
At 4.30am i woke up (i usually wake up then) and the air felt quite stuffy (maybe also because i Knew the PPM). But then i decided to open the door wide and give my wife and baby some fresh air.
If i had left the door shut, the level would have easily reached 4500 ppm until 7am.
The next test that i am about to do is to try keeping the door just 10-20cm open. This is how it how it usually stays. Some quick observations from last nights showed that also in the case CO2 was rising, though not that fast.
10 thoughts on “Sleeping in a Closed Room – Indoor CO2 Analyze”
very interesting !
curious to see the CO2 graph with the door just 10-20cm open.
me too 🙂 i will be away for a few days, but end of next week i should have done it
There is a solution to this : “smartzone ventilation technology”.
This system adapts the ventilationrate using different sensors and was recently awarded the GOLD medal for best building product development in France.
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Hi, thanks for this research. Usually I sleep in small room with closed door seems I am continuously getting too much of CO2 at nights. Could you please share which meter do you use for checking CO2 levels and from where can I get it??
yeah, i am using this CO2 monitor: http://shop.vair-monitor.com/index.php?rt=product/product&product_id=133, which is also manufactured by me. I prefer using the calibration-free models, as the others require fresh air each 3 days, which is a bit hard to grant during the winter months. And w/o this – the accuracy is affected
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I’m not sure your readings are right?
I have tested two nights running and only get an increase of 100ppm per night.
I to am in a 16 metre square room 2.4 m high giving 38000L of air.
I calculated breathing 10L per minute you would breath out 430L on an 8 hour night.
When you breath in, 20% is oxygen and of that you only use 4% .
This means every litre you breath out is appropriately 8000ppm.
430L at 8000 ppm spread over 38000L means an increase of about 90ppm. In 8 hours
This is about what I am seeing with just me in the room.
I am using an MH-Z19B sensor.
Here is the unit I built then added a data logger
Great project 🙂 i like the enclosure, i always stuggled with the 3d printed case of mine 🙁
As for the MH-Z19, i had bought 1 unit and it wasn’t measuring well, it was showing values less than 400 ppm.. then when i tried talking to the support, they told me to recalibrate it, which didn’t work. I know there are lot’s of people that have no issues with it.. and i also wanted to use it due to the price and simplicity, but i was afraid there could be others that do not work. On the contrary – the ones i us haven’t had a failure till now… so i am a little hesitant about the quality of this one.
as for your computations, you are missing a factor of 10 🙂 10L/min *480 minutes/night
the CO2 in exhaled air is ~5%, which is ~240L per night. By default it is 0.04% outside (400 ppm), seldom it is less than 700 ppm at home. Which for 38000 L is ~25L, so you will end up with ~260L of CO2 which is 0.68% or 6800ppm