Bedrooms with the door and window closed averaged 1,150 ppm. With the door or window open, 717. 17 volunteers.
Hogeschool Utrecht, 2018
Aranet4 HOME · No subscription
Aranet4 HOME
People measured their bedrooms. Here’s what they saw.
Owners’ own numbers and a few studies, all in plain words. Heads-up: a lot of these stories end with someone opening a window.
Real owners
Their bedrooms, in their own words.
Aranet4 owners on the bedrooms they measured, quoted word for word.
“my bedroom regularly reaches 3000 in the mornings if no windows are left open.”
“the CO2 in the bedroom got up to 2500ppm”
“we are sharing a bedroom with the kids. It’s cold, we close things... First night I saw CO2 go up to 2500 ppm and I got up to open windows.”
What happened next
Then they opened a window.
The CO₂ number is commonly used as a sign of how much fresh air a room is getting. The window does the work. The screen just tells you when.
“During winter nights we routinely hit 3k-4k in the bedroom by the morning.”
“During summer it never went over 900 due to open window.”
“Solution, get up in the middle of night to open balcony for a few minutes, drops to under 1k very quickly.”
One Aranet4 owner on Hacker News
Researchers measured too
about 60% more
almost 1,000
400–420
It’s not just owners. Researchers have measured bedrooms too.
Here’s what they found, in plain numbers.
ppm in the typical bedroom among 38 in Denmark, measured while people slept, September to December.
Technical University of Denmark, 2022ppm in the air outside, for comparison.
Aranetppm is just the unit CO₂ comes in, the way temperature comes in degrees. On the Aranet4 HOME screen, green turns yellow at 1,000.
1234
What you’ll see
Green, yellow, red. You already know how to read it.
-
The big numberThe CO₂ in your room.
-
TemperatureIn °F.
-
HumidityIn %.
-
The color barGreen below 1,000, yellow from 1,000 to 1,400, red above 1,400.
- See your CO₂ at a glance – no phone needed.
- Real CO₂, measured by a true NDIR sensor.
- Curious how the night went? A free app shows you. It’s optional.
Reviews
“After four years and multiple units, this is still the most dependable CO2 monitor I’ve used. Superbly accurate, runs for months on two AA batteries, and does exactly what it promises.”
“Temp and humidity measurements also seem accurate. Screen is bright and easy to read. Haven’t had to replace the battery yet. Easy to connect to app.”
Do I need another gadget?
It asks for two AA batteries. That’s about it.
- No subscription.
- No Wi-Fi needed, no cords.
- Up to 4 years on two AA batteries.
-
Pop in the batteries
They’re in the box.
-
Set it at breathing height
About 3–6 feet up. Out of direct sun, away from vents and open windows, and not right next to anyone’s face.
-
Glance at it in the morning
That’s the whole routine.
For parents
Kids’ rooms have a number too.
Everyone in a room adds CO₂ when they breathe out, kids included. In a Danish study of 500 children’s bedrooms, about two in three averaged 1,000 ppm or more.
Bekö et al., Building and Environment, 2010.
One for their room. One for yours.
Questions
What does the number mean?
It’s the CO₂ in your room’s air. CO₂ is commonly used as a sign of how much fresh air a room is getting, and when it climbs, the room may not be getting enough. The air outside usually has around 400–420 ppm.
What do people do when the number climbs?
The owners on this page opened a window.
Do I need my phone or Wi-Fi?
No. The screen shows everything on its own, and no Wi-Fi is needed. A free app is there if you want to see how the night went.
Where should I put it?
At breathing height, about 3–6 feet off the floor. Keep it out of direct sun and high humidity, away from vents, open windows and the kitchen, and not right next to anyone’s face.
Does it detect carbon monoxide?
No. Aranet4 HOME measures carbon dioxide (CO₂). For carbon monoxide (CO), you need a dedicated CO alarm.
You’ve seen their numbers. Ready to see yours?
One for your bedroom. Or two: their room and yours, or the bedroom and the office.
See the options
Real owners
Their bedrooms, in their own words.
Aranet4 owners on the bedrooms they measured, quoted word for word.
“my bedroom regularly reaches 3000 in the mornings if no windows are left open.”
“the CO2 in the bedroom got up to 2500ppm”
“we are sharing a bedroom with the kids. It’s cold, we close things... First night I saw CO2 go up to 2500 ppm and I got up to open windows.”
What happened next
Then they opened a window.
The CO₂ number is commonly used as a sign of how much fresh air a room is getting. The window does the work. The screen just tells you when.
“During winter nights we routinely hit 3k-4k in the bedroom by the morning.”
“During summer it never went over 900 due to open window.”
“Solution, get up in the middle of night to open balcony for a few minutes, drops to under 1k very quickly.”
One Aranet4 owner on Hacker News
Researchers measured too
about 60% more
almost 1,000
400–420
It’s not just owners. Researchers have measured bedrooms too.
Here’s what they found, in plain numbers.
Bedrooms with the door and window closed averaged 1,150 ppm. With the door or window open, 717. 17 volunteers.
Hogeschool Utrecht, 2018ppm in the typical bedroom among 38 in Denmark, measured while people slept, September to December.
Technical University of Denmark, 2022ppm in the air outside, for comparison.
Aranetppm is just the unit CO₂ comes in, the way temperature comes in degrees. On the Aranet4 HOME screen, green turns yellow at 1,000.
1234
What you’ll see
Green, yellow, red. You already know how to read it.
-
The big numberThe CO₂ in your room.
-
TemperatureIn °F.
-
HumidityIn %.
-
The color barGreen below 1,000, yellow from 1,000 to 1,400, red above 1,400.
- See your CO₂ at a glance – no phone needed.
- Real CO₂, measured by a true NDIR sensor.
- Curious how the night went? A free app shows you. It’s optional.
Reviews
“After four years and multiple units, this is still the most dependable CO2 monitor I’ve used. Superbly accurate, runs for months on two AA batteries, and does exactly what it promises.”
“Temp and humidity measurements also seem accurate. Screen is bright and easy to read. Haven’t had to replace the battery yet. Easy to connect to app.”
Do I need another gadget?
It asks for two AA batteries. That’s about it.
- No subscription.
- No Wi-Fi needed, no cords.
- Up to 4 years on two AA batteries.
-
Pop in the batteries
They’re in the box.
-
Set it at breathing height
About 3–6 feet up. Out of direct sun, away from vents and open windows, and not right next to anyone’s face.
-
Glance at it in the morning
That’s the whole routine.
For parents
Kids’ rooms have a number too.
Everyone in a room adds CO₂ when they breathe out, kids included. In a Danish study of 500 children’s bedrooms, about two in three averaged 1,000 ppm or more.
Bekö et al., Building and Environment, 2010.
One for their room. One for yours.
