High CO₂ is the measurable signature of an under-ventilated, overcrowded classroom — and the published research links it to slower thinking and lower attainment. Enter your typical CO₂ and we estimate the effective teaching hours lost, and what bringing it down recovers.
Don't know your CO₂? That's the point — measure first. A typical full, naturally-ventilated UK classroom sits at 1500–2500 ppm by mid-morning.
Indicative model based on the published CO₂/cognition relationship (Wargocki & Wyon; Harvard/SUNY COGfx). Real attainment depends on many factors — this estimates the ventilation-attributable share only.
Below ~800 ppm we assume no ventilation penalty. From there, cognitive performance declines roughly linearly with CO₂, reaching about a 15% decrement by 2000 ppm in the controlled studies. We hold it flat above that rather than over-claim. Your penalty is read off this curve at your CO₂.
Penalty% × (hrs/week × weeks)
= effective teaching
hours lost per year
Recoverable =
(penalty@now − penalty@target)
× annual teaching hours
This is a planning estimate to make an invisible problem visible, not a measured outcome. BB101 sets an average CO₂ target below 1500 ppm (1000 ppm for mechanically-ventilated spaces). Persistent readings above that are your evidence base for action.
We supply CO₂ monitoring across a school estate, dashboard the data for your premises team, and advise where ventilation plus HEPA/UV-C makes the difference — priced in your currency.