A modern, energy efficient house is intentionally very air tight, and ventilation is achieved using mechanical ventilation with heat recovery. That basically gi

A modern, energy efficient house is intentionally very air tight, and ventilation is achieved using mechanical ventilation with heat recovery. That basically gives you the best of both worlds - a highly ventilated house (so low humidity levels) coupled with very little heat loss - MVHR systems can often recovery 90% of the heat in the ventilated air. Look at Passivhaus for the most extreme version of this. But even regular new build houses in the UK now have to meet air tightness regulations.