alt Hacker News> because they’re so airtight they require expensive mechanical ventilation and make-up air systems unless you want indoor air pollution problems.
Most modern homes have this issue. Building science has driven them to be air tight bubbles. Look at blower door tests on current construction and a lot of "building science" driven construction.
It's still miles ahead of having literal holes in your window frames to let "fresh air" come in when it's -20c outside.
All you need to do is design a house with a sensible ventilation system, which costs virtually nothing compared to the rest of the building costs. It's even more stupid for americans because they already all have complex ventilation system...