Moved into new (to us, built in 1980) house 2 years ago. Installed an Airthings radon meter a year ago. Levels get up to 400 Bq/m3 when all the windows are closed. Finally had a radon mitigation system installed. Will hopefully get to much safer level below 100 Bq/m3.
It is a lot more complicated than that. Got the final report. They actually do flow testing to see how much air volume they need to achieve a specific vacuum differential, then select piping size and motor type to achieve the required results with the least amount of energy use.
They used an RN2 motor with 4” piping for our house.