ppm on average: bedrooms with the door and the window closed, against bedrooms with either one open. About 60% more. 17 volunteers’ bedrooms.
Hogeschool Utrecht, 2018
Aranet4 HOME · No subscription
Step 2 of 3 · What owners found
Next
What owners saw
People measured their bedrooms. Here’s what they saw.
Owners’ own words, three studies in plain English, and the little screen. Heads-up: most of these stories end with a window.
“Screen is bright and easy to read.”
On this page:
- The numbers owners saw on their screens in the morning
- What happened when they opened a window
- What researchers measured in real bedrooms
Words and numbers fromAranet4 ownersHogeschool UtrechtTechnical University of DenmarkBreatheSafeAirBuilding and EnvironmentAmazon reviews
Guess first
Door shut, windows shut, all night. Guess the morning number.
Your guess: 800 ppm Drag to where you think a closed-up bedroom lands by morning. ppm is just the unit CO₂ comes in, the way temperature comes in degrees.
What owners saw
- You
800 ppm, your guess
- 1
2,500 ppm, a parent’s first night, in a bedroom shared with the kids
- 2
3,000 ppm, one owner’s bedroom in the mornings, with no windows left open
Higher than you guessed.
Right in their range. Good guess.
A little lower than you guessed.
“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.”
“my bedroom regularly reaches 3000 in the mornings if no windows are left open.”
“the CO2 in the bedroom got up to 2500ppm”
On the Aranet4 HOME screen, green turns yellow at 1,000 and red above 1,400.
What happened next
Then they opened a window.
One Aranet4 owner, three moments. Tap through them.
3k–4k
“During winter nights we routinely hit 3k-4k in the bedroom by the morning.”
900 max
“During summer it never went over 900 due to open window.”
under 1k
“Solution, get up in the middle of night to open balcony for a few minutes, drops to under 1k very quickly.”
CO₂ is commonly used as a sign of how much fresh air a room is getting.
1k is owner shorthand for 1,000 ppm.
In plain numbers
Researchers measured bedrooms too.
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, usually. For comparison.
Aranet
1234
What you’ll see
Green, yellow, red. You already know how to read it.
- The big number. The CO₂ in your bedroom.
- Temperature. In °F.
- Humidity. In %.
- The color bar. Green 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 about the room overnight? A free app shows it. It’s optional.
The review
Four years in. Still the one.
“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.”
Do I need another gadget?
It asks for two AA batteries. That’s about it.
1
Pop in the batteries
Two AA. They’re in the box.
2
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.
3
Glance at it in the morning
That’s the whole routine.
- No subscription
- No Wi-Fi needed
- No cords
- Up to 4 years on two AA batteries
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, answered.
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, or the balcony for a few minutes.
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 look back later.
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.
Step 3 of 3
Next: pick your kit. One room or two.
Step 2 of 3 · What owners found
Next
What owners saw
People measured their bedrooms. Here’s what they saw.
Owners’ own words, three studies in plain English, and the little screen. Heads-up: most of these stories end with a window.
“Screen is bright and easy to read.”
On this page:
- The numbers owners saw on their screens in the morning
- What happened when they opened a window
- What researchers measured in real bedrooms
Words and numbers fromAranet4 ownersHogeschool UtrechtTechnical University of DenmarkBreatheSafeAirBuilding and EnvironmentAmazon reviews
Guess first
Door shut, windows shut, all night. Guess the morning number.
Your guess: 800 ppm Drag to where you think a closed-up bedroom lands by morning. ppm is just the unit CO₂ comes in, the way temperature comes in degrees.
What owners saw
- You
800 ppm, your guess
- 1
2,500 ppm, a parent’s first night, in a bedroom shared with the kids
- 2
3,000 ppm, one owner’s bedroom in the mornings, with no windows left open
Higher than you guessed.
Right in their range. Good guess.
A little lower than you guessed.
“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.”
“my bedroom regularly reaches 3000 in the mornings if no windows are left open.”
“the CO2 in the bedroom got up to 2500ppm”
On the Aranet4 HOME screen, green turns yellow at 1,000 and red above 1,400.
What happened next
Then they opened a window.
One Aranet4 owner, three moments. Tap through them.
3k–4k
“During winter nights we routinely hit 3k-4k in the bedroom by the morning.”
900 max
“During summer it never went over 900 due to open window.”
under 1k
“Solution, get up in the middle of night to open balcony for a few minutes, drops to under 1k very quickly.”
CO₂ is commonly used as a sign of how much fresh air a room is getting.
1k is owner shorthand for 1,000 ppm.
In plain numbers
Researchers measured bedrooms too.
ppm on average: bedrooms with the door and the window closed, against bedrooms with either one open. About 60% more. 17 volunteers’ bedrooms.
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, usually. For comparison.
Aranet
1234
What you’ll see
Green, yellow, red. You already know how to read it.
- The big number. The CO₂ in your bedroom.
- Temperature. In °F.
- Humidity. In %.
- The color bar. Green 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 about the room overnight? A free app shows it. It’s optional.
The review
Four years in. Still the one.
“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.”
Do I need another gadget?
It asks for two AA batteries. That’s about it.
1
Pop in the batteries
Two AA. They’re in the box.
2
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.
3
Glance at it in the morning
That’s the whole routine.
- No subscription
- No Wi-Fi needed
- No cords
- Up to 4 years on two AA batteries
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.
Step 3 of 3
