With Chennai’s ambitious metro project underway, the authors wish to explore possibilities of building underground to go with the metro rail stations. This paper looks at the advantages/challenges in going underground, the physical aspects of going underground and some case studies of buildings built underground.
Introduction
Urban areas have always been associated with tall buildings and dense neighbourhoods. Few realise the importance of the under bowels of cities which come masqueraded as basements. New York City would not be able to function without its basements, though they are not well designed spaces. When we think of underground the basic thing that comes to our mind is the stereotype of these spaces as being dark and gloomy. Underground as in many cultures is a metaphor for virtual host of negative associations: death, darkness, cold, dampness, and deceit. This preconception has deeply embedded in the psychology of most people. However, going underground has a host of features to offer and this paper will be exploring the advantages and challenges of building underground.
With the advent of Chennai Metro, Chennai goes underground for the first time. This opens up many opportunities for well designed subterranean spaces that are accessible to the metro rail stations. Shopping malls, cultural centres, libraries, art galleries, theatres, offices, etc. are some spaces that could be associated with Chennai Metro as it takes a deep dive into the grounds of the city. Such associations are pretty common in developed countries where trains form a central role in society. Such spaces could help to glamorise the metro and make it hit the ground running, unlike the maligned MRTS project which is yet to take off in terms of usability.
Advantages/Challenges of building underground
Although they can be expensive and difficult to construct, underground facilities offer many important advantages over surface structures. The biggest advantage of going underground is that it enables us to replenish the ground cover, and not spoil the visual impact of the adjacent environment. . Diminishing the surface footprint of a building creates or preserves open space, provides habitat for local animals, enhances the visual environment, and lets rain fall directly on the living earth.
Underground buildings can provide thermal comfort and can reduce our energy cost by 50-80%. The other added advantage of going underground is that it doubles the usage of the land. Their depth can make them resistant to conventional and some nuclear attacks. Surprisingly, experience in Japan and San Francisco has shown that underground buildings are remarkably safe in earthquakes. Additional advantages include lower long-term maintenance costs (because underground structures are not exposed to weather).
Underground placement sometimes offers a practical solution to a vexing problem. For example, elementary schools located under the flight paths for the Los Angeles and Phoenix airports have quiet classrooms because of earth sheltering. Precision instrument factories located inside bedrock can function without traffic-induced vibration or expansion/contraction of materials due to fluctuating temperatures.
But the problem in going underground is that you have to remove the soil layer to create the spaces, which is very expensive and in some cases you have to cut the rocky terrains which is very expensive and laborious, and you to deal with the structure that is going to bear the soil load above, and incorporating the earth quake resistance measures is a costly affair, and other than this you have your air circulation and day lighting criteria which has to be seriously addressed.
Although they can be expensive and difficult to construct, underground facilities offer many important advantages over surface structures. The biggest advantage of going underground is that it enables us to replenish the ground cover, and not spoil the visual impact of the adjacent environment. . Diminishing the surface footprint of a building creates or preserves open space, provides habitat for local animals, enhances the visual environment, and lets rain fall directly on the living earth.
Underground buildings can provide thermal comfort and can reduce our energy cost by 50-80%. The other added advantage of going underground is that it doubles the usage of the land. Their depth can make them resistant to conventional and some nuclear attacks. Surprisingly, experience in Japan and San Francisco has shown that underground buildings are remarkably safe in earthquakes. Additional advantages include lower long-term maintenance costs (because underground structures are not exposed to weather).
Underground placement sometimes offers a practical solution to a vexing problem. For example, elementary schools located under the flight paths for the Los Angeles and Phoenix airports have quiet classrooms because of earth sheltering. Precision instrument factories located inside bedrock can function without traffic-induced vibration or expansion/contraction of materials due to fluctuating temperatures.
But the problem in going underground is that you have to remove the soil layer to create the spaces, which is very expensive and in some cases you have to cut the rocky terrains which is very expensive and laborious, and you to deal with the structure that is going to bear the soil load above, and incorporating the earth quake resistance measures is a costly affair, and other than this you have your air circulation and day lighting criteria which has to be seriously addressed.
Physical factors to consider while building underground
Ventilation and air circulation-
Ventilation and air circulations plays the major role in underground structures, we have to maintain at least two to three air change rate per hour, so that intoxicants like carbon monoxide and other harmful elements are remove and the supply of fresh air is maintained, the air movement should be enough to cause psychological cooling, in underground there should be a separate inlet and outlet structure for the air to come in and go out,
In the most of the existing cases the wind catchers and mechanical systems are used to draw the air in, the air is filtered out and circulated below the window level so that when the air raises up and it cools the surrounding by the process of convection and the heat energy which is dissipated due to the human activities and by the use of machineries is carried along with the rising air and which is vented through solar chimneys, these chimneys works on the principle of stack effect and creates the suction that removes the stale air and helps in air circulation. In some cases the air conditioning units are installed for cooling and maintaining the quality of the air
These chimneys has the glass coverings at the top which heats the air, the hot air raises up there by creating the suction, which helps the stale air to move out.
Ventilation and air circulations plays the major role in underground structures, we have to maintain at least two to three air change rate per hour, so that intoxicants like carbon monoxide and other harmful elements are remove and the supply of fresh air is maintained, the air movement should be enough to cause psychological cooling, in underground there should be a separate inlet and outlet structure for the air to come in and go out,
In the most of the existing cases the wind catchers and mechanical systems are used to draw the air in, the air is filtered out and circulated below the window level so that when the air raises up and it cools the surrounding by the process of convection and the heat energy which is dissipated due to the human activities and by the use of machineries is carried along with the rising air and which is vented through solar chimneys, these chimneys works on the principle of stack effect and creates the suction that removes the stale air and helps in air circulation. In some cases the air conditioning units are installed for cooling and maintaining the quality of the air
These chimneys has the glass coverings at the top which heats the air, the hot air raises up there by creating the suction, which helps the stale air to move out.
Day lighting-
Lighting has its own importance in the built environment, in underground spaces the importance of lighting becomes more, as there is a general perception that underground spaces are dark, gloomy, cold and is always associated with death, deceit etc, minimum requirement of light inside a building is 500 lux, proper sunlight is also needed inside a building to ward off any microbial growth which may disintegrate the building so in an underground structure there must be a provision of lighting probably at the top as the other sides remain inside the ground.
For lighting, openings may be left in the roof which may be covered at the top by glass or any other transparent or translucent material which does not restrict the entry of light inside the building, in this case we can go for fully glazed roofing but it is costly and may heat up the building basically in these kind of buildings we go for artificial lighting to light up the space.
Lighting has its own importance in the built environment, in underground spaces the importance of lighting becomes more, as there is a general perception that underground spaces are dark, gloomy, cold and is always associated with death, deceit etc, minimum requirement of light inside a building is 500 lux, proper sunlight is also needed inside a building to ward off any microbial growth which may disintegrate the building so in an underground structure there must be a provision of lighting probably at the top as the other sides remain inside the ground.
For lighting, openings may be left in the roof which may be covered at the top by glass or any other transparent or translucent material which does not restrict the entry of light inside the building, in this case we can go for fully glazed roofing but it is costly and may heat up the building basically in these kind of buildings we go for artificial lighting to light up the space.
Climatology
Chennai has a warm and humid climate. Average temperature ranges from 27-40 deg C. The presence of sea near the city increases the humidity, and therefore going underground will be a challenging task. In underground spaces due to the lack of enough air movement, the air gets stagnant; and due to the sweating and other human activities the humidity level increases which causes discomfort underground. But this has an advantage as well, as we go down to a depth of 3-4m we can achieve a stable temperature which is equal to the average of extreme temperatures. As we go down further the temperature decreases by 1deg Celsius per meter. Therefore this makes the underground spaces cool during the summer and warm during the winters. This in turn reduces the energy consumption of heating or cooling the building.
Chennai has a warm and humid climate. Average temperature ranges from 27-40 deg C. The presence of sea near the city increases the humidity, and therefore going underground will be a challenging task. In underground spaces due to the lack of enough air movement, the air gets stagnant; and due to the sweating and other human activities the humidity level increases which causes discomfort underground. But this has an advantage as well, as we go down to a depth of 3-4m we can achieve a stable temperature which is equal to the average of extreme temperatures. As we go down further the temperature decreases by 1deg Celsius per meter. Therefore this makes the underground spaces cool during the summer and warm during the winters. This in turn reduces the energy consumption of heating or cooling the building.
Geology
The geology and soil properties along with the ground water conditions determine technically speaking the way the subsurface activities can take place. underground structures have to bear the following forces/loads:- lateral forces, due the land movement which is a result of tectonic activities, load on top of the surface.
The geology and soil properties along with the ground water conditions determine technically speaking the way the subsurface activities can take place. underground structures have to bear the following forces/loads:- lateral forces, due the land movement which is a result of tectonic activities, load on top of the surface.
Case studies
Some buildings by David J. Bennett, FAIA
Bennett designed and oversaw construction of half a dozen subterranean buildings in Minnesota's twin cities of Minneapolis and St. Paul. They ranged from a single-story structure nestling in topsoil to a building burrowed into bedrock 112 feet below the surface. Determined to dispel the stereotype of underground spaces as being dark and gloomy, Bennett devised a variety of innovative techniques for drawing daylight into his buildings.
Some buildings by David J. Bennett, FAIA
Bennett designed and oversaw construction of half a dozen subterranean buildings in Minnesota's twin cities of Minneapolis and St. Paul. They ranged from a single-story structure nestling in topsoil to a building burrowed into bedrock 112 feet below the surface. Determined to dispel the stereotype of underground spaces as being dark and gloomy, Bennett devised a variety of innovative techniques for drawing daylight into his buildings.
1. Williamson Hall, University of Minnesota
His first underground creation was Williamson Hall, a University of Minnesota building that houses administrative offices and the campus bookstore. Bennett daylighted its interior in a straightforward manner, using large expanses of windows. Recessing a triangular courtyard in the two-story-deep building provided three walls that could be filled with windows. Angling the windows at 45 degrees from the vertical increased their surface area and, consequently, their ability to transmit sunlight. The strategy was effective in making Williamson Hall the "sunniest building on campus," although its large, sloping windows were vulnerable to heat loss in the winter.
His first underground creation was Williamson Hall, a University of Minnesota building that houses administrative offices and the campus bookstore. Bennett daylighted its interior in a straightforward manner, using large expanses of windows. Recessing a triangular courtyard in the two-story-deep building provided three walls that could be filled with windows. Angling the windows at 45 degrees from the vertical increased their surface area and, consequently, their ability to transmit sunlight. The strategy was effective in making Williamson Hall the "sunniest building on campus," although its large, sloping windows were vulnerable to heat loss in the winter.
2. Holaday Circuits factory and corporate office building
Bennett again relied on windows to transmit daylight. This time, however, he placed the windows on top of the structure, leaving the entire floor area of the building available for manufacturing and administrative activities. Some of the windows became the south faces of rooftop boxes called daylight monitors. Placing these glass panels vertically maximized their thermal efficiency. One skylight strip atop a building-long corridor employed a different kind of efficiency. During daylight hours, these sloping panels admitted a maximum amount of natural light; at night, light fixtures mounted above them served double duty by illuminating the hallway below while serving as outdoor security lighting.
Bennett used an even more imaginative daylighting scheme for the windows along a shallow, recessed courtyard provided natural light and exterior views to rooms on the first subsurface level of this building. One floor below, office workers could enjoy sunshine and scenery through a simulated window. Long, angled mirrors at the top and bottom of a vertical shaft essentially created a wide periscope. The angles of the mirrors allowed them to function well for workers seated at their desks, but the view was less realistic when viewed from a standing position.
Bennett again relied on windows to transmit daylight. This time, however, he placed the windows on top of the structure, leaving the entire floor area of the building available for manufacturing and administrative activities. Some of the windows became the south faces of rooftop boxes called daylight monitors. Placing these glass panels vertically maximized their thermal efficiency. One skylight strip atop a building-long corridor employed a different kind of efficiency. During daylight hours, these sloping panels admitted a maximum amount of natural light; at night, light fixtures mounted above them served double duty by illuminating the hallway below while serving as outdoor security lighting.
Bennett used an even more imaginative daylighting scheme for the windows along a shallow, recessed courtyard provided natural light and exterior views to rooms on the first subsurface level of this building. One floor below, office workers could enjoy sunshine and scenery through a simulated window. Long, angled mirrors at the top and bottom of a vertical shaft essentially created a wide periscope. The angles of the mirrors allowed them to function well for workers seated at their desks, but the view was less realistic when viewed from a standing position.
3. Civil and Mineral Engineering Building at the University of Minnesota in Minneapolis
Bennett created his most ambitious light management devices for the Civil and Mineral Engineering Building at the University of Minnesota in Minneapolis. The state legislature decreed that the building should be designed to test and showcase new technologies for underground space utilization in addition to providing instruction, research, and administrative spaces.
Along one side of the building, windows faced a recessed courtyard. Windows in some interior walls let sunlight shine farther into the building. Along the other side of the building, a light monitor on the roof served as an entrance for natural light. A long, south-facing mirror directed sunlight into the north-facing monitor. Carefully placed lenses and reflective surfaces dispersed the light throughout the building's interior.
Yet another light path began in a glass-topped cupola containing a movable mirror that tracked the sun and sent its beams down to the deepest levels of the building, providing a swatch of sunlight 112 feet below the surface.
Bennett also devised a periscope-like system of lenses and mirrors to deliver a remote view of the surface to the lowest floor of the building. The view was good enough to allow building occupants to see what the weather was like outside. However, because the scene was visible from only one spot, the simulated window seemed unnatural. Furthermore, cost-saving modifications to the original design made the equipment difficult to maintain.
Bennett created his most ambitious light management devices for the Civil and Mineral Engineering Building at the University of Minnesota in Minneapolis. The state legislature decreed that the building should be designed to test and showcase new technologies for underground space utilization in addition to providing instruction, research, and administrative spaces.
Along one side of the building, windows faced a recessed courtyard. Windows in some interior walls let sunlight shine farther into the building. Along the other side of the building, a light monitor on the roof served as an entrance for natural light. A long, south-facing mirror directed sunlight into the north-facing monitor. Carefully placed lenses and reflective surfaces dispersed the light throughout the building's interior.
Yet another light path began in a glass-topped cupola containing a movable mirror that tracked the sun and sent its beams down to the deepest levels of the building, providing a swatch of sunlight 112 feet below the surface.
Bennett also devised a periscope-like system of lenses and mirrors to deliver a remote view of the surface to the lowest floor of the building. The view was good enough to allow building occupants to see what the weather was like outside. However, because the scene was visible from only one spot, the simulated window seemed unnatural. Furthermore, cost-saving modifications to the original design made the equipment difficult to maintain.
Friedrichstrasse, Berlin
After the fall of the Berlin Wall, the municipality of Berlin decided to revitalize Friedrichstrasse, formerly a fashionable shopping area. With three different designers involved and their own interpretation of the brief, the result was a series of independent mega structures lining Friedrichstrasse. In addition to seven stories above ground, each unit contains four sublevels. All the units are connected underground by spacious shopping streets.
In an attempt to reintroduce the typical Berlin building style, many of the units along Friedrichstrasse and in the surrounding area have courtyards. In one of the units, the Galeries Lafayette, designed by French architect Jean Nouvel, stands a remarkable structure. The four sides of the building are of glass and round at one corner. The innumerable reflections this creates provide a spectacular image. The transparency of the building is enhanced by reflections of artificial light. The masterstroke of the unit is the way the building has been cored. Two cones of glass, placed one on top of the other, bore like a whirlwind through the unit from top to bottom. The first cone reaches its largest diameter at the level of the ground floor and the second tapers downward from that point. The logical result is that natural light penetration is optimized and transported deep down into the building. At ground level, the cone is open, offering a view of all eleven storeys.
Conclusion
Though there are physical challenges and human prejudices to overcome, building underground can offer many advantages, and can be a visually stimulating experience. If taken up seriously, this opportunity can be a shot in the arm for Chennai’s metro rail project, and could help arrest the glamour of urban sprawl and fast cars.
References
1.Meijenfeldt, Enrst von; Below Ground Level – Creating New Spaces for Contemporary Architecture; Birkhauser, 2003
2.Hall, Loretta; Underground buildings – Architecture and Environment; subsurfacebuilding.com, 2002
After the fall of the Berlin Wall, the municipality of Berlin decided to revitalize Friedrichstrasse, formerly a fashionable shopping area. With three different designers involved and their own interpretation of the brief, the result was a series of independent mega structures lining Friedrichstrasse. In addition to seven stories above ground, each unit contains four sublevels. All the units are connected underground by spacious shopping streets.
In an attempt to reintroduce the typical Berlin building style, many of the units along Friedrichstrasse and in the surrounding area have courtyards. In one of the units, the Galeries Lafayette, designed by French architect Jean Nouvel, stands a remarkable structure. The four sides of the building are of glass and round at one corner. The innumerable reflections this creates provide a spectacular image. The transparency of the building is enhanced by reflections of artificial light. The masterstroke of the unit is the way the building has been cored. Two cones of glass, placed one on top of the other, bore like a whirlwind through the unit from top to bottom. The first cone reaches its largest diameter at the level of the ground floor and the second tapers downward from that point. The logical result is that natural light penetration is optimized and transported deep down into the building. At ground level, the cone is open, offering a view of all eleven storeys.
Conclusion
Though there are physical challenges and human prejudices to overcome, building underground can offer many advantages, and can be a visually stimulating experience. If taken up seriously, this opportunity can be a shot in the arm for Chennai’s metro rail project, and could help arrest the glamour of urban sprawl and fast cars.
References
1.Meijenfeldt, Enrst von; Below Ground Level – Creating New Spaces for Contemporary Architecture; Birkhauser, 2003
2.Hall, Loretta; Underground buildings – Architecture and Environment; subsurfacebuilding.com, 2002
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