Any home with an ACH nat of 1 that's attempting to condition the air (heating or cooling) is wasting a mind boggling percentage of the energy. Surely that's not the natural ventilation rate of the _typical_ home? That would imply that 50% of homes are worse.

This reference suggests that the mean air change rate in southern europe is 1.1 +/- 0.8 ac/h. https://www.researchgate.net/publication/265511654_Proportio....

Do you live in a wind-tunnel?

But if it's hot air touching cool brick, won't the air cool down quicker than the brick warms up?

The air inside is only a tiny fraction of a building's mass.