Due to the possibility of there being an underground water table, there was a need for the building to be constructed on a reinforced concrete raft foundation. This foundation rests on bedrock. The bedrock plays an essential interaction with the footings of all walls and is also reinforced. Due to the pressure that is acting on the back wall of the building through the soil that is behind the wall, a kicker was needed in order to act as a prevention measure. This was to prevent the soil pushing the wall forward on the foundation.
The berm house needs to be waterproof to prevent any water moving through the earth that surrounds it and causing damage to the building’s walls. This can be done by using a method called tanking.
The above photo shows the tanking of the berm house.
The tanking is a bituminous material that acts as an impermeable barrier to any water that penetrates the earth covering the building. It envelopes the building so that potential water damage to internal walls is vastly reduced.
The outer skin of the cavity wall acts as a shutter for the waterproof tanking material. The building needs to be entirely waterproofed. It also needs to be a lasting characteristic and not semi-permanent. If the tanking fails then it would be a very costly measure to remove and replace the tanking.
Photo showing the tanking material.
The earth that is banked against the walls of the building, and also the earth that can be situated on the roof of the building, can act as a thermal regulator. The earth will draw extra heat away from the building during hot weather and insulate the building during winter weather.
The roof needs to be designed very accurately, due to the amount of weight that it needs to support the weight of the soil that is placed on top of the roof. In order to do this pre-stressed concrete beams were used, which contain reinforcing steel ropes. Once they are put into place a concrete grout is placed on top of the concrete beams. The roof then needs to be tanked and the tanking of the roof needs to be incorporated into the tanking of the perimeter structures.
There is also a form of earth-sheltered building that is known as “Earthship”. This form constructs houses that are built to be self-contained and independent. The design of such buildings allows food to be grown indoors, maintenance of water and solar electrical systems. Such buildings perform the environmentally conscious aspect by using unusual building materials. Materials such as, aluminium cans being used to fill non load-bearing walls.
Thermal Factors
To keep the temperature of a building warm, there is a need to replace the heat that escapes the building. Conduction is one way in which heat is lost; the amount of heat that is lost through conduction varies on a combination of factors. These factors are internal temperature, external temperature and conductivity of building materials. The practice of covering the house with soil, acts as a form of insulation.
For the site that has been mentioned in this report, there is extra insulation located four inches behind the outer masonry wall. There is also extra insulation that is located in the ceiling of the living areas, which is covered by a vapour barrier.
Heat escape from a building is also lost when it is replaced by cold air. All the windows that are fitted in the building are all sealed windows with no openings; this reduces any exchange of warm and cold air occurring at these areas. Every room that is in the building is separated from the outside with three tight fitting doors, again minimising the amount of cold and warm air exchanges occurring. With the majority of the building’s walls are underground, there is very little heat lost through the ground that covers the buildings.
Any “waste” air that is taken from the internal environment, and extracted to outside. The air extracted is warm air, and as it passes through the duct, it passes heat to the cold air that is being pumped into the building. This is achieved by running the extraction duct through the middle of a larger duct in which the cold air is being pumped into the building. The heat passes from the warm air to the cold air, thus ensuring that although there is new “clean” air being pumped in, there is not a significant decrease in the temperature drop.
Heating of the building is obtained through the use of the windows located in the south facing wall of the building. Due to the south facing nature of the windows, they gain more heat from the sun during the year. This reduces the need for a separate heating system to be installed. The heat energy that is gained from the windows acts as the main source of the building’s heat.
Conclusion
In conclusion, although the initial costs of the construction of a berm house are a lot higher than that of a conventional house build, there are advantages that are gained. These advantages include, susceptibility to the impact of extreme outdoor temperatures is lowered, there is a more stable internal temperature, and, the effects of external weather are not felt to such a degree in a conventional house.
There is also the advantage of reducing the amount of menial tasks that need to be done. Such as the amount of guttering that needs to be installed and maintained being limited to just one external wall, and tasks such as painting external walls. There is some natural soundproofing, provided by the soil, and there is greater defence against high winds or extreme weather.
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