A bedroom spent 72% less time above 1,000 ppm after one routine changed.
Aeroshi found recurring overnight CO2 buildup in one bedroom. The household began ventilating more deliberately, and later comparable nights improved.
- Before
- 120 min
- After
- 34 min
- Difference
- 72% less
The investigation
Room-level comparison turned an indoor-air concern into a testable operational decision.
- The pattern01
20 of 24 nights
In February, the bedroom rose above 1,000 ppm on most adequately covered nights.
- The response02
Ventilate more
After seeing the pattern, the household opened windows more often and ventilated more heavily.
- What followed03
14 of 16 nights
Weather-matched later nights had lower bedroom peaks than their February comparisons.
Why room comparison mattered
The bedroom behaved differently from the rest of the home.
Across 159 comparable nights, bedroom peaks were higher than the lounge on 89% of nights. That made the next decision specific: change the bedroom routine, then check whether the pattern followed.
The practical change
Open windows more often and ventilate the bedroom more heavily.
What happened next
120 to 34
minutes above 1,000 ppm
This comparison uses 16 later nights matched to February nights within 1°C of outdoor temperature. It reduces the chance that warmer weather alone explains the difference.
Bedroom CO2 across the study
Median nightly peak, 22:00-07:00 on adequately covered nights
February Bedroom
1,096 ppm
July Bedroom
595 ppm
How we checked this
Fixed monitoring
Four rooms, using 15-minute readings across 159 adequately covered comparable nights.
Same-home comparison
The lounge provided a second room under the same household and broad weather conditions.
How to interpret it
The precise change date, window position and occupancy were not recorded, so the result is an observed association rather than proof of cause.
Use room-level monitoring to test an indoor-air decision
Scope the rooms, operating change and evidence audience. Aeroshi provides monitoring, analysis and a report that shows what was observed before and after.