It’s not clear from the press release whether this is a UK rollout or just in England- I suspect the latter - at last count there were 302 thousand classes in English schools, so this number makes sense.
But maybe they were for the ones where they're use was (particularly) not pointless? I.e. those with consistent high readings, with simple measures like opening windows not helping (or for some reason not being practical).
It would make more sense to me to send 7-8k of them to say London schools than 20k to country schools.
Seems a bit tough to ever make them practical without central AC though, which is not common (nor any AC) in the UK.
One interview I heard called it 'gesture politics'. Sadly, I think that assessment is on the money. It's just not plausible that there are only 7k classrooms in the UK that have bad ventilation.
I think it's the deep malaise of UK politics that they just hate spending money on anything, even if it will save far more money in the future. It's why the UK has the GDP-per-capita of Japan, but mostly looks like Serbia.
> Is ten classrooms per school a reasonable average?
That sounds low: a secondary school with no sixth-form will have students in 5 different year groups, and will typically have more than two classes per year group.
There are 8,911,853 pupils in England alone with an average class size of 26.6
That's 335,032 classes, and thus at least 335k classrooms (add extra ones for specialist classrooms)
However that number includes private schools. Remove those and you're looking at 8.3 million, with a larger class size, so potentially just 277k classes assuming 30 people per room (plus specialist classrooms like IT, Art, D+T, PE, etc)
Presumably, 300,000 CO2 monitors is in the right range for one per classroom? Is ten classrooms per school a reasonable average?