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Earth sheltered houses: Past, present and future

Posted by Alex Barrett on 1 December 2016 at 12:40 pm

We have a long history of living in earth sheltered houses. Some of the earliest human dwellings made use of caves, and throughout human history there have been occasions where building your house into a hillside proved far more effective than leaving it exposed.

The ground is a good insulating material and retains a lot of heat once it is warmed up. Covering your walls with earth protects them from the environment and has a lot of thermal advantages. Let’s take a look at earth sheltered houses through the ages, from ancient turf buildings, to the earthships and green roofs of the modern day.

In the past

Earth sheltered houses have been used both in cold parts of the world such as Iceland where they provide good insulation, and in warmer regions like Australia, where living underground can keep a dwelling cool. Earth has a high thermal mass, so it retains heat very effectively. It insulates the building, preventing heat loss and heat gain, and keeping the internal temperature constant regardless of the weather outside.

The heat retaining properties of turf were used extensively in medieval Iceland. Building extensively in wood was not a viable solution, as trees are not very common. The cold climate and inclement weather also means that houses require a lot of insulation in order to keep their occupants warm. Houses were built with walls of stacked turf around a light wooden structure. Slabs of turf are cut, and piled around the hose. These then grow together to create a solid, well insulated structure. Turf houses were in use as early as the Iron Age, and remained common up until the nineteenth century [1].

Present day

Modern earth sheltered houses come in several varieties [2]. The simplest to construct are earth bermed houses. A bank of earth called a berm is piled up around the outside of the walls to provide extra support and insulation. The earth berm might extend all the way around the property as with turf houses, or it might only support a few of the walls, generally those which are pole facing, since these will get the least sun throughout the day.

Other structures go further and cover the roof with soil as well. These are generally called “in-hill buildings” [3, 4]. Some are built into a hillside, while others are much larger in scope. Some have a ring of rooms built into the ground around a sunken courtyard. Of course it is also possible to build a house completely underground and this has been used to great effect in Australia where old mines have been converted into dwellings that stay cool in the hottest weather [5].

Brigton Earthship

One of the most sustainable templates for an earth sheltered dwelling is the “earthship” [6]. This design incorporates recycled materials such as earth packed tires. It is designed to be easy to build by hand. More technologically intensive designs involve a shell of concrete surrounded by earth. In either case good waterproofing is required between the earth bank and the building, so as to ensure that a partly buried house doesn’t flood in bad weather.

Earth sheltered houses can be built fairly cheaply, using sustainable materials, or they can be energy intensive feats of engineering. In either case building one is a large undertaking, and not very easy to retrofit. Earth berms can be constructed around an existing building, but clearly this won’t be feasible for every property.

Green Roofs

There is an increasing trend towards green, or living roofs. A thin layer of earth is added to the roof, so that plants can be grown on that space. Installing a green roof has a variety of advantages, both for the property and the environment. Again they are most easily installed on new builds, as not all existing buildings are strong enough for the extra weight of earth.

Green roofs originated in Germany in the early twentieth century. At the time it was typical for roofs to be waterproofed using bitumen. This had to be covered with a layer of sand so as to cut down on the risk of fire. The sand layer quickly accumulated plants and the environmental benefits of a green roof were soon recognised. Green roofs have now become a widespread element of urban design. The government is increasingly supporting the development of this technology [7] and 165,000 m² of green roofs were installed in London between 2004 and 2008 [8].

Earth sheltered houses have been keeping us warm for thousands of years, and hopefully they will continue to do so for the foreseeable future.

Sedum roof

References

  1. Scribol.com
  2. Inspiration Green
  3. Low Impact: Earth Sheltered Houses
  4. Energy.gov
  5. Outback Australia Travel Secrets
  6. Earthship Project
  7. Islington Council
  8. Low Impact: Living Roofs

Photo 1: Alex Barrett 2013. Reconstructed turf house in southern Iceland.
Photo 2: Brighton Earthship
Photo 3: Sedum roof, SuperHomes

If you have a question about anything in the above blog, please ask it in the comments section below.

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