I didn't understand the purpose as pressurising the structure. I understood the purpose as ventilating the interior, providing a central place to attach a filter, and preventing air from coming in from other places.
I edited my post above to hopefully make it a bit more clear, but it seems you get it right away! Cheers
>they didn't want to stop air coming in
The neat thing is, if you're already accepting this heat loss penalty anyway (in the service of positive pressure), it greatly reduces or even eliminates the ERV you need to maintain good indoor CO2. So in addition to better indoor AQI, positive pressure can greatly reduce total equipment cost.
Seems like a win/win to me!
Buckminster Fuller proposed a similar scheme in his Dymaxion House (even removing dust via baseboard vents), but it used passive heating and cooling so there was little penalty.
No AI of course.