The seeking of shelter within the earth is no unique idea; man, and animal alike have exploited the protective and insulative properties of the soil long before recorded history, developing sophisticated, yet simple, means of dealing with harsh climates and hostile environments. From arid deserts to polar cold regions, subterranean dwellings offer refuge from exposure to the sun, wind, storm, and extreme variations in atmospheric temperatures, as well as providing thermal compensation for seasonal temperature changes. Apart from that, with the increase in urban cities in the world, urban land is expected to become a limited resource, climate change is also a major phenomenon. So we can provide a better living environment by designing underneath and thus increasing natural open spaces on the land. The spaces created underneath requires a different set of structural and constructional rules.
Beyond producing immediate and “natural” shelter, the practice of underground architecture possesses a tremendous heritage that, although poorly if ever documented in architectural history texts, is rich in spatial variety, responding to environmental issues factors with design solutions addressing accessibility, ventilation, and light. An architectural adobe above the soil can be perceived as a product addition that includes various spatial enclosures with different volumes. The spaces beneath the earth are the result of positive negative spaces with a difference in the type of structural and constructional rules.
The first inhabitants of underground space were troglodytes or cave-dwellers. Many of man’s first architectural attempts were artificially created caves. It is no accident that men and entire cultures have not done the practice of cave-dwelling and “cave-building. An in-depth historical overview is mentioned further to understand the evolution of the underground dwelling system. Currently, it is technically possible to build underground living spaces for people. But are we willing to spend a long period in subterranean dwellings?
The Building Concepts
A wide variety of approaches exists within the concept of the underground building. At one extreme, a building can be erected on the original surface of the ground (i.e. at grade) and then be covered by earth to shelter the building partially or completely. At the other extreme, the building is constructed in a completely excavated site (i.e. Below grade). In between there are several different other types of underground building concepts that can be distinguished as shown in Figure, this does not include every design possible, but gives a typological overview.
(a) Fully underground spaces
These spaces have little or no contact with the above world. These are the spaces below the ground completely. Only the entrance will be above the ground. So these spaces have a supply of light and air. The absence of natural light and views makes prolonged stays underground less appealing.
(b) Submerged Spaces.
Submerge spaces are the ones lying just under the surface of the ground. They possess the ability to extend deep into the ground but they always have direct contact with the above-ground world and with natural light. To admit daylight, the surface of the ground is perforated by various elements like patios, atriums, and domes. An atrium can transport daylight to great depths, providing not only natural light but also some external views. In any event, a view of the sky provides contact with the seasons, the weather and the time of day.
(c) Earth Covered Spaces.
An earth-covered building is not entirely underground, but rather at grade, having a surface laid over it. This building type is free of the technical disadvantages of an underground building while enjoying its advantage of spatiality. Daylight can penetrate and views are usually unimpaired. The elevated ground level can be laid out as a park, landscape, or urban environment as well. In the majority of cases, earth-covered buildings can be constructed traditionally with a unique touch of its own.
So, from the above these are the following variables that reflect the potential of Subterranean Architecture having significant characteristic:
The table below shows a comparative analysis of four cases located in different zones. It reflects a description of the above mentioned eight parameters.
With its unique feature of spatiality, underground architecture can be deeply explored in various terms to introduce a different dwelling system in today’s era of land scarcity and climate change. But along with these added advantages, certain limitations will surely challenge the existing advantages of underground Architecture.
The major limitation can be the lack of adaptability and acceptance for the subterranean dwelling system as there is a direct relation with the psychological reactions of a feeling of claustrophobia, fear of collapse, etc. When it comes to the living system, the provision of basic necessities becomes a major concern. So, the foremost solution should be portrayed for the supply of water, fresh air, and electricity. This leads us to the thought of openings and ventilation, wherein most of the case studies the parameter of ventilation is merely solved by the AC Ducts which does not solve the problem of Openings to be provided to sustain an entire living system beneath the ground.
The accessibility is one of the major concerns when it comes to connecting or reaching these systems with the neighbourhoods. This function must relate and fulfil the visual as well as the physical parameter. As we dig underground, there is a major possibility of degradation of the environment, unfavourable geology, water table problems, Confined work Conditions, Cost certainty, etc.