A big part of why this works so well in German homes is that they have a high thermal mass. Even single family homes are built with concrete floors and plastered over brick walls (brick as in square building block, I think the currently popular form is expanded concrete?).
In these buildings, you can replace all air with outside air at once, and once you close the windows the thermal mass of the building will quickly heat it up again.
New buildings tend to move away from it though, instead using automatic fans for ventilation
In these buildings, you can replace all air with outside air at once, and once you close the windows the thermal mass of the building will quickly heat it up again.
New buildings tend to move away from it though, instead using automatic fans for ventilation