Before I came up with my current system I spent a lot of time looking into actuators for windows. They exist but they're expensive, often bulky and look like a lot of work to install and maintain. Then it occurred to me that I already have a whole-house fan (HVAC system)... if I could just get it to draw from outside rather than from the air returns. That part woks great and I think it does give me a pretty good single point of control. The only problem is that the house is pretty tight so I also needed a way to create some negative pressure, hence the laundry room to attic fan. I think that's still my airflow bottleneck.
As for whether I've crunched the numbers.... no, I haven't. And since I installed solar last year it maybe doesn't even matter any more? Throughout most of the summer I'm actually giving away nearly a MWh per month of electricity even after running house, A/C, car, steam shower, etc. So it's really more of a game to me than a serious attempt to save money. That said, I do watch my energy consumption closely (game, right?) and running the fans consumes maybe 400W. Overnight that's about 3.2 kWh. Meanwhile, my AC draws 4 kW, so if my AC kicks on for 45 minutes it consumes as much as the passive system does all night. And for that, the passive system cools the house by ~10F degrees while the AC will cool it by about 2F, which would indicate 5X efficiency improvement. But even that doesn't fully capture it, because the AC will cool the *air* by 2F while the passive system will cool the house and also much of the thermal mass, so it's actually moving quite a bit more heat out than the thermostat temperatures would indicate.
So, yeah, an order of magnitude more efficient seems about right. When outside air cools down at night!
I've also been thinking about building something for my shop. It's an uninsulated pole barn (30' wide x 40' long x 25' high) which gets quite hot in the summer and quite cold in the winter. I think some automated fans to exploit day/night temperature variations could probably move the average interior temperature several degrees closer to comfortable, year round. Even better if I insulate it.