Because its open outdoor space and adjacent rooms and entrances are all below ground, the atrium style delivers the most privacy and the greatest amount of protection from the vagaries of nature (high winds, thunder storms, tornadoes, hurricanes, wildfires, etc.).
However, because it is literally a hole in the ground, the atrium can easily fill with snow in a blizzard or rainwater in a tempest, which can cause flooding and drainage problems if some kind of system for diverting rain or melting snow has not been installed.
Because the living areas are entirely beneath ground level, the rays of the sun are not able to enter at a low enough angle to provide ample amounts of natural light, and because the central outdoor space opens directly to the empty sky, the views enjoyed from inside the home are only as good as the effort that has gone into creating an attractive atrium space.
The elevational style, strictly speaking, is neither underground nor bermed, but is more of a combination of both. Elevational homes are built directly into hillsides or mountainsides, looking almost as if they have been inserted into the mouth of a cave, to enough depth to completely cover the side and back walls of the home.
The front of the house is left open to the air, usually facing the south in order to harvest the natural heat and light provided by the daily sun.
Roof covers are normally added to such a home to complement the berm-like sheltering effect of the hillside, and houses constructed in the elevational style have shallow rectangular shapes that feature bedrooms and living spaces arranged linearly in the foreground so the sun can provide heat and light to all the important rooms of the house.
Elevational homes are the least expensive type of earth-sheltered structure to construct, and with their hillside locations they frequently offer grand panoramic views of surrounding natural vistas.
Penetrational homes are built above ground, but are designed to fully exploit the protective abilities of the earth. Each wall of a home constructed in the penetrational style is completely bermed, with only the spaces over doors and windows left open to facilitate easy entrance, good cross-ventilation, and the effective harvesting of natural light.