There are two different types of earth sheltered house :
COLD CLIMATE TYPE and Hot CLIMATE TYPE
They are different in the way they work . . . . and how they need to be designed.
COLD CLIMATE - usually found in Europe and the USA :
HOT CLIMATE - the Australian type
So, let's be clear - the Cold Climate and Hot Climate types are completely different, and that Northern Hemisphere practices will not fit with Australian conditions - there are exceptions, but they are rare.
There's a lot of information on the internet that is either out of date or not applicable to the Australian Building Codes, or our climates.
We in Australia have terrific climates, from the temperate and alpine regions to the tropical and sub-tropical zones . . . most of the year we can spend a lot of time outdoors, and so we at ShelterSpace advocate the use of readily accessible outdoor living areas that capture the breezes and shield the occupants from harsh sunlight.
A typical internal temperature range within our homes is between 15 to 25 degrees.
My place once reached a maximum of 26 degrees inside. . . . but it was 46 degrees outside.
Usually in summer the inside is around 22 degrees.
ShelterSpace earth sheltered house at Bendameer NSW