Souterrain (below ground) or underground passages designed primarily as food storage areas, were ventilated, but draft free.
They maintain a constant temperature of around 4 degrees no matter how hot it gets on the surface. They could also be used as places of refuge during attacks on the Ring Fort, many souterrain have secondary or tertiary chambers which are difficult to enter, thereby affording their occupants a measure of security. Kids, big and small, just love them!