Earth shelter

Earth acts as thermal mass, making it easier to maintain a steady indoor air temperature and therefore reduces energy costs for heating or cooling.

One of the oldest examples of berming, dating back some 5,000 years, can be found at Skara Brae in the Orkney Islands off northern Scotland.

[2] The majority of publications about earth sheltering date to this period, with dozens of books dedicated to the topic being published in the years leading up to 1983.

[9] Other notable proponents of earth sheltering active in this era include Mike Oehler, Rob Roy, John Hait, Malcolm Wells, Peter Vetsch, Ken Kern and others.

[13] Some postulate that over time the reducing availability of building space, and the increasing need and interest for environmentally friendly housing will make earth shelters more common.

The "low tech" approach might involve natural building techniques, wooden posts and shed style roofs, recycling of materials, owner labor, hand excavation, etc.

The atrium arrangement provides a much less compact plan than that of the one or two-story bermed/in hill design; therefore it is commonly less energy efficient, in terms of heating needs.

In culvert homes ("Cut and Cover"), precast concrete containers and large diameter pipes are arranged into a connecting design to form a living space and then backfilled with earth.

[5] An experimental construction design from the 1980s of Japan, coined 'Alice City', proposed to use a wide and deep cylindrical shaft sunk into the earth, with a domed skylight roof.

In most of the Northern Hemisphere, a south-facing structure with the north, east, and west sides covered with earth is the most effective application for passive solar systems.

In 1981, Oehler promoted his low-budget building design (a simple hole in the ground with walls of wooden planks backed by plastic sheeting) by claiming it needed no foundation, used less building material and labour, had less maintenance, was aesthetically pleasing, had a lower taxation rate in the US at the time, cost less to regulate temperature, was less affected by stormy weather, had pipes which wouldn't freeze where they entered the house, were "ecologically sound", relatively fireproof, soundproof and had an increased garden space as compared to regular house on a similarly sized plot of land.

[17] The most superficial layer of earth typically is less dense and contains the root systems of many different plants, thereby acting more like thermal insulation,[14] meaning, it reduces the rate of temperature flowing through it.

[24] For example, raising poultry and domesticated animals is an important part of the traditional Chinese rural human settlements and these elements create a stable and sustainable ecological cycle that benefits the environment.

[22] Compared to other building materials, such as wood, earth houses feature efficient fire protection owing both to the use of concrete and the insulation provided by the roof.

For example, yaodong and pit cave dwellings in Northern China hide themselves underground and blend in perfectly within the Loess plateau environment.

[4] A small "underground home" built in the style of Oehler, as only a simple, non-waterproofed hole in ground with simple planks and a plastic sheet to a wall, despite using free labour (ignoring the opportunity costs of not having time to go to work) and recycled materials, e.g. windows and planks for the wall, is estimated to be 30% cheaper to construct when compared to paying a contractor to build a regular house using new construction materials at standard prices,[4] although Oehler's design will quickly rot and collapse after a few years.

The specific architecture of earth houses usually leads to non-righted, round-shaped walls, which can cause problems concerning the interior decoration, especially regarding furniture and large paintings.

Problems of water seepage, internal condensation, bad acoustics, and poor indoor air quality can occur if an earth shelter has not been properly designed and ventilated.

[14] Compared to above ground house, earth-shelters may have limited escape routes in case of emergency,[26] which can fail egress and fenestration building codes.

For bermed or in-hill construction, a common plan is to place all the living spaces on the side of the house facing the equator (or north or east, depending on latitude).

Well graded gravels have a large bearing capacity (about 8,000 pounds per square foot), excellent drainage and a low frost heave potential.

A few ways to protect against capillary action responsible for frost heaves are placing foundations below the freezing zone or insulating ground surface around shallow footings, replacement of frost-sensitive soils with granular material, and interrupting capillary draw of moisture by putting a drainage layer of coarser material in the existing soil.

In regions such as the southeastern United States, earth sheltering may need additional care in maintenance and construction due to condensation problems in regard to the high humidity.

[28] Brick or stone masonry reinforced with steel bars can be utilized for walls that will be subjected to lateral or vertical pressure from earth cover.

Wood can be widely employed in earth-sheltered buildings for structural and internal work, including floors, roofs, and exterior walls.

The advantage is that steel has high tensional and compressional strength, while the disadvantage is that it must be protected from corrosion if it is exposed to air, water, or other chemicals.

Terra-Dome (USA) is a company specializing in construction of earth-sheltered houses and sells a modular system of concrete domes intended to be covered by earth.

Epoxies are very brittle so they are paired up with an overcoat of a high-build flexible water-based acrylic membrane in multiple coats of different colors to ensure film coverage—this is reinforced with non-woven polypropylene textile in corners and changes in direction.

Foam insulation requires an additional protective top coat such as foil or fleece filter to help it resist water penetration.

[14] Some advise that topsoil and turf (sod) be put aside from the initial excavation and be used for the grass roof and to place as the topmost layer on the berm.