Drafty houses are not healthy houses: timber needs to be able to dry out to stay rot-and mold-free, but draftiness is associated with weakened immune systems and therefore poorer health. The draftiness rule only holds for older houses constructed before insulation, where the draftiness is needed to counteract the cool, stone/brick basement collecting moisture. A modern house design for insulation should be tight and mechanically ventilated, both for the maintenance of the structure and for human health.
