Most high quality modern homes are built to be air tight and bring air in with exchangers. Monopoly framing is how they are approaching this with stick frame houses. They essentially create what looks like a building from the game Monopoly (no overhangs) with air tight materials and tape every hole they can find. They will install a blower door and measure how much air leaks from the building envelope. The overhanging features are installed outside of the air tight monopoly frame.
All of the Zip boards are air and water tight and they use the tape on all of the seams to seal those. The roof will sit on top of the already water & air tight frame. Same with the siding.
I had trouble with my heating system and got a good long talk with the HVAC pro.
I think variable output heating/cooling has one interesting capability - it can adjust to things you've adjusted. For example, a one or two-stage heating system has trouble if you close heating vents in some rooms. It might overheat if too many are closed for example. With a variable-output system, it can support this. further with variable dampers it can support zoned heating and cooling. You can give the places that need it less or more airflow and have a more comfortable house without waste.
after seeing things like heatermeter (pid controlled smoker controller based on the raspberry pi), I wonder why this kind of convenient and efficient control isn't more common.