Ventilation ensures that the house has fresh air both in sumer and winter.

Summer Ventilation 

Summer ventilation makes use of the fact that hot air rises.  Hot air is vented from the top of the second story, and cool air is drawn in through an EarthTube from a cool part of the garden.

Winter Ventilation

Winter ventilation makes use of a heat recovery ventilator. This device uses the outgoing warm air to warm up the incoming coolair.