An Energy Factsheet
An earth-sheltered building is either banked on one
or more sides with earth, or built partially or entirely
underground. This approach to building is one way
to more effectively control a building’s interaction
with its surrounding environment. Earth-sheltering
reduces a building’s energy needs for heating and/
or cooling by (1) preventing the leakage of air out
of and into the building, and (2) placing a barrier
between the walls of the building and the extreme
outdoor temperatures. In the more temperate areas
of Alaska the average ground temperature for depths
of 5 to 10 feet below the surface ranges from 35° F
at Anchorage to 41° F in Juneau.
Earth sheltering does not need to result in a
dark or damp environment. On the contrary, by
exposing the south-facing walls and windows to the
outdoors and making use of clerestory windows,
an earth-sheltered building can be bright and airy
The building site is central to the planning of an earth-
sheltered home. Soil and ground water conditions
will determine structural and waterproofing
requirements. Some soils are more susceptible than
others to expansion when wet or frozen, and will
place more demands on the strength of the building.
Permafrost areas occur in Alaska and special care
should be taken during preliminary site preparation
to ensure the ground is not disturbed when
permafrost is present. Because of this, earth-sheltered
homes are not recommended for permafrost areas.
Soil testing may be needed at this critical stage in
the design phase.
The topography of the site — lay of the land
— will affect wind flow and drainage patterns,
and will determine how easily the building can
be surrounded by earth. A modest slope requires
more excavation than a steep one, and a flat site is
the most demanding, needing extensive excavation.
Buildings on flat ground are bermed more easily on
one or more sides. Berming is the practice of banking
earth up against the walls of the building.