>In one part they mention the study was done in 2015 (no link to article) on 24% where people did 61-101% better on some test.

I think this is the study

https://dash.harvard.edu/bitstream/handle/1/27662232/4892924...

>Results: On average, cognitive scores were 61% higher on the Green building day and 101% higher on the two Green building days than on the Conventional building day (p < 0.0001). VOCs and CO2 were independently associated with cognitive scores