Ventilation rate raises information processing.
The claim
Ventilation rate is how much fresh outdoor air a space brings to each person, usually measured in litres per second per person or read off the CO2 that builds up when air moves too slowly. When a room supplies more fresh air, the people in it work faster and make fewer errors on tasks that need focus: arithmetic, reading, comparing numbers, reasoning through a problem. The effect shows up most in classrooms and offices where people sit for long stretches and CO2 climbs through the day.
The findings
Allen (2016) found cognitive scores 101 percent higher on days in a high-ventilation building than in a conventional one, and 61 percent higher in a green building, all at p < 0.0001. Petersen (2016) raised outdoor air from an average of 1.7 to 6.6 litres per second per person. Correct answers rose across all four tests: addition by 6.3 percent, number comparison by 4.8 percent, grammatical reasoning by 3.2 percent and reading and comprehension by 7.4 percent.
Wargocki (2020) puts the classroom gain at 12 percent in speed when CO2 falls from 2,100 to 900 ppm. Satish (2012) found large drops in seven decision-making scales at 2,500 ppm against 600 ppm, with raw score ratios from 0.06 to 0.56. Zhang (2017) reported slower addition, longer response times and fewer correct links in a cue-utilisation test when CO2 from bioeffluents reached 3,000 ppm.
Certainty
Allen (2016) and Wargocki (2020) support the link, spanning field experiments in occupied buildings (Allen 2016), controlled classroom and chamber exposures (Petersen 2016, Zhang 2017, Satish 2012) and a synthesis (Wargocki 2020). Nine studies stand behind this factor. The effect sizes are large and repeatable across arithmetic, reading and decision tasks. The two nulls both sit in one setting: Fan (2023) and Klausen (2023) varied CO2 during sleep and tested the next morning, after people had left the exposure, so they speak to overnight air rather than working during the day. No study reports gains above 10 litres per second per person, so the upper end of the range is untested.
In practice
A room can raise fresh air supply toward 6.6 litres per second per person and expect measurable gains in arithmetic, reading and reasoning tasks, on the scale Petersen (2016) recorded across four separate tests. Where CO2 is already tracked, holding it below roughly 900 ppm rather than letting it climb past 2,100 ppm captures the 12 percent speed gain Wargocki (2020) reports. This applies to classrooms and offices where people sit through long stretches and CO2 accumulates over the day. Spaces used mainly overnight sit outside this case. Fan (2023) and Klausen (2023) both varied CO2 during sleep and found no next-morning difference in cognitive performance. A bedroom's ventilation rate should not be treated as a change on daytime work output unless the occupant is still in that air while working. Above 10 litres per second per person the benefit is unmeasured, so pushing ventilation past that point for cognitive reasons has no supporting figure to aim at. The documented effect sits in tasks performed during the fresh air supply, not after people have left it, so a ventilation change earns credit for a performance gain only where task and exposure overlap in time.
Dose and thresholds
Gains run from roughly 2 litres per second per person up to about 10, the range Wargocki (2020) covers; Petersen (2016) measured its improvements moving from 1.7 to 6.6 litres per second per person. Above 10 litres per second per person no data exist, so the ceiling of the benefit is unknown.
Where it is contested
Fan (2023) and Klausen (2023) both found no difference in cognitive performance between CO2 conditions, but each tested the morning after sleep. Fan (2023) exposed people overnight in the bedroom and ran the tests the next day. Klausen (2023) varied CO2 during sleep and tested next-morning after time in well-ventilated rooms, and reported no significant exposure effects on cognitive performance.
The mechanism
Poor air raises arousal and stress: Zhang (2017) found bioeffluents at 3,000 ppm lifted diastolic blood pressure and salivary α-amylase, both markers of a sympathetic response, alongside slower cognitive scores. Fresh air keeps that activation down, so attention holds steady through the day.
What each profession does with this factor.
- ArchitectOutdoor air rate is the ventilation number worth specifying
- Asset managerVentilation moves the rent only through the whole certification label
- Corporate real estateAir quality outweighs the energy line
- Developer and investorA CO₂ logger shows the air a building delivers; a green rating does not
- HR and workplaceMore outdoor air raises measured task performance
- MarketingOnly the ventilation category is an air claim you can verify
- Workplace strategistVentilation raises cognitive performance
The Built Review. TBR-F-2813 (v1): Ventilation rate raises information processing. https://thebuiltreview.com/factors/ventilation-rate-information-processing Licensed CC BY 4.0.
More from these studies
31 studysheets from 8 of the studies above
Some state this factor, the rest are what else those papers found.
+1.7%
office task performance improves with each doubling of ventilation rate
Doubling the ventilation rate improved office work performance by 1.7% on average
PAWEL WARGOCKI et al., 2000, Indoor air
+6.3%
better ventilation improved children's addition test scores
Higher ventilation rate improved addition test scores by 6.3%
S. Petersen et al., 2016, Indoor air
+3.2%
better ventilation improved children's grammatical reasoning scores
Higher ventilation rate improved grammatical reasoning scores by 3.2%
S. Petersen et al., 2016, Indoor air
+4.8%
better ventilation improved children's number comparison scores
Higher ventilation rate improved number comparison scores by 4.8%
S. Petersen et al., 2016, Indoor air
+7.4%
better ventilation gave the largest boost to reading and comprehension scores
Higher ventilation rate improved reading and comprehension scores by 7.4%
S. Petersen et al., 2016, Indoor air
bioeffluents at 3000 ppm CO2 increased fatigue and sleepiness
Bioeffluent exposure at 3000 ppm CO2 increased reported fatigue and sleepiness
X. Zhang et al., 2017, Indoor Air
bioeffluents at 3000 ppm CO2 reduced perceived air quality
Bioeffluent exposure at 3000 ppm CO2 reduced perceived air quality
X. Zhang et al., 2017, Indoor Air
bioeffluents at 3000 ppm CO2 slowed cognitive task performance
Bioeffluent exposure at 3000 ppm CO2 reduced speed and accuracy on cognitive tasks
X. Zhang et al., 2017, Indoor Air
bioeffluents at high CO2 reduced cognitive performance on a cue-utilization test
Bioeffluent exposure at 3000 ppm CO2 reduced performance on a cue-utilisation cognitive test
X. Zhang et al., 2017, Indoor Air
bioeffluents at high CO2 significantly raised diastolic blood pressure
Bioeffluent exposure at 3000 ppm CO2 significantly increased diastolic blood pressure compared with pre-exposure levels
X. Zhang et al., 2017, Indoor Air
bioeffluents at high CO2 significantly raised salivary α-amylase, a stress marker
Bioeffluent exposure at 3000 ppm CO2 significantly increased salivary α-amylase compared with pre-exposure levels
X. Zhang et al., 2017, Indoor Air
higher end-tidal CO2 and less heart rate decrease at very high CO2 levels
Exposure to 3000 ppm CO2 (added or via restricted ventilation) altered physiological responses compared to reference conditions
X. Zhang et al., 2017, Indoor Air
>1,300 ppm
a modeled projection of indoor CO₂ in 2100 under a business-as-usual scenario and current ventilation codes
Indoor CO₂ could exceed 1300 ppm by 2100 if buildings are ventilated to current standards, under a business-as-usual emissions scenario
Asit Kumar Mishra et al., 2021, Indoor air
11–23% lower
decision-making scores drop at 1,000 ppm CO₂ compared to 600 ppm
Decision-making scores dropped 11–23% at 1,000 ppm CO₂ vs. 600 ppm
Usha Satish et al., 2012, Environmental Health Perspectives
44–94% lower
decision-making scores collapse at 2,500 ppm CO₂ compared to 600 ppm
Decision-making scores fell 44–94% at 2,500 ppm CO₂ vs. 600 ppm
Usha Satish et al., 2012, Environmental Health Perspectives
35–93% lower
doubling CO₂ from 1,000 to 2,500 ppm cuts decision-making scores sharply
Going from 1,000 to 2,500 ppm CO₂ cut decision-making scores by 35–93%
Usha Satish et al., 2012, Environmental Health Perspectives
6–56% of baseline
at 2,500 ppm CO₂, decision-making scores fell to as little as 6% of the low-CO₂ baseline
At 2,500 ppm CO₂, decision-making scores were only 6–56% of baseline values
Usha Satish et al., 2012, Environmental Health Perspectives
−13%
a 500-µg/m³ rise in total VOCs was independently linked to lower cognitive function scores
A 500-µg/m³ rise in total VOCs was linked to a 13% drop in cognitive scores
Joseph G. Allen et al., 2016, Environmental health perspectives
−15%
ASHRAE-acceptable CO₂ level still cut cognitive scores by fifteen percent
CO₂ at ~945 ppm (an ASHRAE-acceptable level) reduced cognitive scores by 15%
Joseph G. Allen et al., 2016, Environmental health perspectives
−50%
CO₂ at 1,400 ppm halved cognitive scores vs. low-CO₂ conditions
CO₂ at 1,400 ppm cut cognitive scores by 50% compared to ~550 ppm
Joseph G. Allen et al., 2016, Environmental health perspectives
+25%
doubling outdoor air supply from 20 to 40 cfm per person raised cognitive scores by a quarter
Doubling outdoor air ventilation raised cognitive scores by 25%
Joseph G. Allen et al., 2016, Environmental health perspectives
+18%
each extra 20 cfm per person of outdoor air was linked to higher cognitive scores
Each additional 20 cfm/person of outdoor air was associated with an 18% increase in cognitive scores
Joseph G. Allen et al., 2016, Environmental health perspectives
−21%
every 400-ppm rise in indoor CO₂ was linked to a fifth fewer cognitive function points
Every 400-ppm rise in CO₂ was linked to a 21% drop in cognitive scores
Joseph G. Allen et al., 2016, Environmental health perspectives
+61%
green building conditions raised cognitive function scores well above conventional office levels
Green building conditions boosted cognitive scores by 61% vs. conventional buildings
Joseph G. Allen et al., 2016, Environmental health perspectives
+101%
high-ventilation low-VOC conditions more than doubled cognitive scores over a conventional building day
Green+ (high ventilation) building conditions more than doubled cognitive scores vs. conventional buildings
Joseph G. Allen et al., 2016, Environmental health perspectives
+299%
information usage scores nearly four times higher under Green+ than conventional conditions
Information Usage scores were nearly 3× higher under Green+ vs. conventional conditions
Joseph G. Allen et al., 2016, Environmental health perspectives
+288%
strategy and planning scores nearly four times higher under Green+ than conventional conditions
Strategy scores were nearly 4× higher under Green+ vs. conventional building conditions
Joseph G. Allen et al., 2016, Environmental health perspectives
44.1 min
average time for children to fall asleep in the climate chamber
Mean sleep onset latency in climate chamber was 44.1 minutes
Frida Bejder Klausen et al., 2023, International Journal of Occupational Medicine and Environmental Health
6 of 10
Cognition trended slightly better after low-CO₂ sleep on 6 of 10 test outcomes, but the study found no statistically significant effect of CO₂ on cognition
Cognitive performance showed a non-significant numerical trend toward better scores after low-CO₂ sleep on 6 of 10 CANTAB outcomes
Frida Bejder Klausen et al., 2023, International Journal of Occupational Medicine and Environmental Health
+10.5 min
children fell asleep more slowly in a low-CO₂ room than in a poorly ventilated high-CO₂ one
Sleep onset latency was 10.5 minutes longer under low CO₂ conditions vs. low-ventilation high-CO₂ with bioeffluents
Frida Bejder Klausen et al., 2023, International Journal of Occupational Medicine and Environmental Health
+19.2 min
children took longer to fall asleep in a well-ventilated low-CO₂ room than in a high-CO₂ one
Sleep onset latency was 19.2 minutes longer under low CO₂ conditions vs. high CO₂ with added pure CO₂
Frida Bejder Klausen et al., 2023, International Journal of Occupational Medicine and Environmental Health