Earth-Sheltered Home Design

If you are looking for a home with many energy-efficient features that will provide a comfortable, tranquil, weather-resistant atmosphere, an earth-sheltered house could be right for you.

There are two basic types of earth-sheltered houses:

    * Underground

    * Bermed (or banked with earth)

Both types usually have earth-covered roofs. Some roofs may have a vegetation cover to reduce erosion.

To help determine what type of earth-sheltered house and design might work best, you should consider the following:

    * Advantages and Disadvantages of Earth-sheltered homes

    * Site-specific design factors

    * Construction Materials and Other Consideration

Designing Underground Earth-Sheltered Homes

When an entire earth-sheltered house is built below grade or completely underground, it's called an underground structure. The atrium or courtyard design can accommodate an underground, earth-sheltered house.
Atrium or Courtyard Design

An earth-covered dwelling may have as little as 6–8 inches (0.2 meters) of sod or as much as 9 feet (2.7 meters) of earth covering the structure. An atrium design offers an open feeling because it has four walls that give exposure to daylight. This design uses a subgrade open area as the entry and focal point of the house.

The house is built completely below ground on a flat site, and the major living spaces surround a central outdoor courtyard. The windows and glass doors that are on the exposed walls facing the atrium provide light, solar heat, outside views, and access via a stairway from the ground level. Atrium/courtyard homes are usually covered with less than 3 feet (0.9 meters) of earth primarily because greater depths do not improve energy efficiency. This style also offers the potential for natural ventilation.

The atrium design is hardly visible from ground level and barely interrupts the landscape. It also provides good protection from winter winds and offers a private outdoor space. This design is ideal for an area without scenic exterior views, in dense developments, and on sites in noisy areas. Passive solar gain—heat obtained through windows—might be more limited, due to the window position in an atrium plan. Courtyard drainage and snow removal are important items to consider in design.

Designing Bermed Earth-Sheltered Homes

A bermed earth-sheltered house may be built above grade or partially below grade, with outside earth surrounding one or more walls. Such a structure can accommodate more conventional earth-sheltered house designs, such as elevational and penetrational.
Elevational Design

Elevational plans expose one whole face of the house and cover the other sides—and perhaps the roof—with earth. The covered sides protect and insulate the house. The exposed front of the house, usually facing south, allows the sun to light and heat the interior. The floor plan is arranged so common areas and bedrooms share light and heat from the southern exposure.

This type of house may be placed at varying depths below ground level and is usually set into the side of a hill. The view provided will be one of landscape, rather than open sky, as in the atrium design. A structure designed in this way can be the least expensive and simplest to build of all earth-sheltered structures.

The elevational design may have limited internal air circulation and reduced daylight in the northern portions of the house, though there are ways to alleviate these problems by using skylights. The wide design of the house can be offset by close attention to architectural details, landscaping, and exterior materials.
Penetrational Design

In a penetrational design, earth covers the entire house, except where it is retained for windows and doors. The house is usually built at ground level, and earth is built up (or bermed) around and on top of it. This design allows cross-ventilation opportunities and access to natural light from more than one side of the house.

The design you choose will ultimately depend on the geography and climate of your location, your budget, and your own preferences.

Read about green landscaping in Humboldt County, California

Learn about other Green Building techniques.

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