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Contents (Jump to)
Chapter 1: Introduction
Section 1.1: Overview of the dissertation
Section 1.2: The need for sustainable building solutions
Section 1.3: Underlying principles and mechanisms
Chapter 2: Solutions from Nature
Section 2.1: Wind-induced ventilation of the burrow of the prairie dog, Cynomys ludovicianus
Section 2.2: Other notable investigations
Chapter 3: Examples of Buildings that incorporate sustainable features derived from natural examples
Chapter 4: Conclusions
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Chapter 1: Introduction
Section 1.1: Overview of the dissertation
This dissertation will focus on looking at how Nature can provide sustainable building solutions, in particular for wind-induced natural ventilation systems. The first part of the dissertation will look at the need for sustainable building solutions, in terms of the damage that has been, and continues to be, wrought on the Earth’s natural systems, and the possible solutions that can be found by studying how Nature has developed solutions to the problems of ventilations in burrows, and the need for gas exchange. The fact that Nature has produced these solutions is discussed as an event occurring over evolutionary time, through the process of natural selection. Subsequent sections of the dissertation discuss the physical principles that have been mastered by the process of evolution, such as the Bernoulli Principle and the Venturi effect, which has led to the appropriate, sustainable, solutions that are found in Nature.
These principles are discussed in detail in Chapter 2, in terms of their appearance in natural systems: the burrows of the black-tailed prairie dog, Cynomys ludovicianus, the complex burrow and cone system of the mud shrimp Callianassa truncata and the burrow-mound system of the goby Valencennea longippinis which allows for increased gas exchange to the developing eggs in the burrow. The three examples are discussed in detail, in terms of the relevant literature and experimental studies that have been performed to determine how and why the animals produce such structures.
Chapter 3 presents some examples of buildings that have applied solutions found from Nature to provide sustainable living spaces. Examples include, amongst others, several buildings designed by Eugene Tsui, such as the residence of Florence and William Tsui in Berkeley, California, the Watsu School at Harbin Hot Springs, the Exposition Building for the International Celebration of Innovation and the Tsui Design and Research Inc. Headquarters in Emeryville, California, and the the Kanak Cultural Centre in Noumea, New Caledonia designed by Renzo Piano.
The dissertation concludes with Chapter 4, which presents some concluding remarks, concerning the fruitfulness of looking to Nature for ideas for sustainable building, for looking to Nature can prove a valuable exercise, for as Tsui, one of the great contemporary ‘organic’ architects states in his book Evolutionary Architecture: Nature as a Basis for Design, “Every great discovery that has marked the upward surge of humanity has been an insight into some profound aspect of natural phenomena. Every tool, every medicinal remedy, every scientific venture, every exploration of the physical and psychological world is a glimpse of the ineffable mind of nature a mind that has no beginning, no end, no dimension and no parameters; a mind that is compelled to create, produce, evolve, differentiate and regenerate with such perfection and thoroughness as to be the model for every human endeavour”.
Section 1.2: The need for sustainable building solutions
Mankind is slowly killing the Earth and its natural systems. We are living with unacceptable levels of carbon dioxide in the atmosphere, which is leading to increases in the greenhouse effect and widespread climate changes across the globe. These climate changes are causing problems for many systems, amongst them agriculture, making it much more difficult for those in sub-Saharan Africa, for example – which is increasingly affected by drought and erratic rainfall patterns – to be self-sufficient in terms of being able to grow enough crops to survive. Other experts predict changes in the circulation of ocean currents due to global warming, which is leading to a melting ice reserves and glaciers and causing far greater volumes of water to enter the ocean circulatory systems. Shifts in the circulation of ocean currents could have grave consequences for mankind.
In addition to the problems created by increases in atmospheric carbon dioxide, pollution of the Earth’s water system has occurred on a massive scale, with experts predicting potential future problems with supplies of non-polluted water that is suitable for human use. The Earth, the blue planet, full of water and previously perfectly balanced, is facing unprecedented onslaughts to its vital systems, due to the excessive, wasteful and polluting habits of mankind.
What can be done about this? It is fundamental that legislation be put in place now to preserve the Earth and its systems, and that we begin to act, individually and collectively, to save the Earth and its resources that are of fundamental value to us. Sustainability is a fundamental concern for all of humankind, as the population of the Earth begin to realise that we only have one Earth and that it needs to be looked after. By listening more closely to, and taking lessons from, the Earth and the inhabitants we share the Earth with, we can begin to live much more harmoniously and in concert with – not antagonistically with – the Earth and its inhabitants.
The construction, use and maintenance of buildings contributes significantly to adverse environmental impacts, such as carbon dioxide production, something that will only get worse as the population increases and the need for housing grows. Many recent regulations and conventions have already been put in place to ensure that sustainable building principles become the norm in future; for example, a recent convention has been signed to reduce the discharge of hazardous chemicals to zero by 2020, and, documents such as the 1999 policy document entitled A better quality of life – a strategy for sustainable development for the United Kingdom, provide targets for sustainability within the construction industry.
As many contemporary architects realize, nature itself is fully harmonious, with all of its parts working in harmony with each other, from species interacting but co-existing in a habitat, on a small scale, to – on a larger scale – the ocean circulation systems working in harmony to deliver nourishing currents across the globe. This harmony has been violated by the actions of mankind, and, through mankind not recognizing and respecting this harmony, we have arrived at the situation we are in with the Earth and its systems and inhabitants being exposed to very real threats. It is perhaps time that architects begin to study Nature and her solutions in order to arrive at sustainable building solutions.
As Tsui, one of the great contemporary ‘organic’ architects states in his book Evolutionary Architecture: Nature as a Basis for Design, “Every great discovery that has marked the upward surge of humanity has been an insight into some profound aspect of natural phenomena. Every tool, every medicinal remedy, every scientific venture, every exploration of the physical and psychological world is a glimpse of the ineffable mind of nature a mind that has no beginning, no end, no dimension and no parameters; a mind that is compelled to create, produce, evolve, differentiate and regenerate with such perfection and thoroughness as to be the model for every human endeavour”.
Looking at the natural world for inspiration can be a valuable exercise. Subsequent sections of the dissertation will look at specific examples of wind-induced ventilation, from the black-tailed prairie dog, the mud shrimp and the goby. These examples will show how each of these animals has adapted their immediate environment fully in harmony to the immediate environment, to the benefit of themselves and to their wider community. The ideas of organic, or ‘evolutiionary’ architects, such as Tsui, are based on similar principles, that architects should start, on a wide scale, to look to nature for sustainable building solutions.
Looking to Nature for answers to building problems should, argues, Tsui (1999) become part of an architects repertoire. As Tsui (1999) argues, Nature is not driven by ambition, it has no preconceptions, no concept of style, and her evolution has been through small patient incremental steps, only allowing the ‘correct’ ones to persist, where ‘correct’ means the solution that is most fitting for the particular situation, the solution that is sustainable, to allow in-situ permanence.
As energy consumption and the by products from air conditioning are amongst the most significant contributors to the destruction of the Earth’s systems, the subject of this dissertation is to look for natural examples of wind-induced ventilation systems that could, potentially, be incorporated in practical solutions for the construction industry, in terms of finding sustainable building solutions. Although it is understood that understanding the mechanics of nature’s microclimate control will not provide any quick-fix solutions to cooling buildings, these natural examples achieve equilibrium with their surroundings that is far beyond the reach of mankind at this time and, as such, by studying these systems, they can be learnt from and their novelties applied in design and building practice. Looking to natural examples of wind-induced ventilation will, therefore, potentially provide solutions to heavily polluting air conditioning systems.
Section 1.3: Underlying principles and mechanisms
Many animals need to live in burrows or to produce burrows for protection from the elements, for example, or for protection from predation. As shall be seen in later sections of the dissertation, the need for such burrows means that some elegant solutions to the problems such burrows present (such as a lack of ventilation) have been reached, as in the case of the black-tailed prairie dog, and that the burrows themselves can create favourable micro-environments and favourable conditions for the larger habitat, as in the case of the complex burrow and cone systems of the mud shrimp.
An implicit understanding, and mastery, of physical principles of nature has been built up by these species over evolutionary time. This section of the dissertation will discuss some of these physical principles, including the Bernoulli principle, the Venturi effect and the Venturi tube. The Bernoulli Principle states that “for an ideal fluid, with no work being performed on the fluid, an increase in velocity occurs simultaneously with a decrease in pressure or a change in the fluid’s gravitational potential energy”. Essentially, fluid particles are only subject to pressure and their own weight, meaning that within a flowing fluid, the highest speed occurs when the pressure is lowest and the lowest speed occurs when the pressure if highest, with Bernoulli’s equation stating that the sum of all forms of energy in a fluid flowing across a streamline is the same at any two points along the path. Bernoulli’s Principle explains how water drains from a bowl in a circular pattern around the axis of the drain and also explains how one feels pulled towards large vehicles if they pass by you at high speed.
The Venturi effect is a specific example of the more general Bernoulli Principle, which explains how fluids can pass through a region of incompressible flow through a tube with a constriction in it, in which situation the velocity of the fluid increases through the restriction and the pressure decreases in order to satisfy the equation of continuity and to ensure the flowing of the fluid through the constricted space. It is on this principle, for example, that the burrows of the black-tailed prairie dog is thought to work, as shall be seen in Section 2.1 of the dissertation, with the volcano device for air acceleration being applicable to underground structures of every kind. A series of venting volcanoes could be aligned with underground rooms containing air-exiting vents to produce individually vented spaces. This phenomenon can be employed and rising warm air can be directed out exiting vents, as in the burrows of the prairie dog dwelling. It is thought that, by using the prairie dog system, air can be interchanged at a rate of 2550 cubic feet per minute with no utility power (Tsui 1999). The prairie dog mounds and volcanoes have been likened to a half Venturi tube where a Venturi tube is used to determine the flow-rate of fluids or air through a pipe. The Venturi tube has a specialized streamlined constriction that minimizes the energy losses in the fluid flowing through it and which, thus, maximizes the fall in pressure in the constriction in line with Bernoulli’s principle.
These principles will be discussed in further detail in Chapter 2, in terms of their appearance in natural systems: the burrows of the black-tailed prairie dog, Cynomys ludovicianus, the complex burrow and cone system of the mud shrimp Callianassa truncata and the burrow-mound system of the goby Valencennea longippinis which allows for increased gas exchange to the developing eggs in the burrow.
Chapter 2: Solutions from Nature
Section 2.1: Wind-induced ventilation of the burrow of the prairie dog, Cynomys ludovicianus
The black-tailed prairie dog, Cynomys ludovicianus, is a ground-dwelling squirrel, one of four prairie dog species to be found uniquely in North America. Black-tailed prairie dogs live in colonies, which are generally established in cattle-grazed areas, as the prairie dogs prefer the vegetation surrounding their burrows to be short, so they can keep an eye out for predators. The black-tailed prairie dogs live in burrows, with one principle tunnel and, depending on the size of the colony, various numbers of side chambers that act as overnight housing for the prairie dogs. Unfortunately, as with many other native species, habitat destruction is causing a drastic reduction in the number of black-tailed prairie dogs (Hoffman, 1999), with conservation efforts currently underway to stabilize the population numbers of the black-tailed prairie dog (see, for example, Andelt, 1988).
As Vogel et al. (1973) argue, where a fluid flows across a surface – for example wind over the earth – a velocity gradient is created which provides a potential source of work. This gradient might, for example, be employed by a burrowing animal to induce air-flow in its burrow, which is long and narrow to avoid the obvious risks presented by predators. The burrow of the black-tailed prairie dog, long and narrow as it is, being, on average, 12cm in diameter and 10-30m in length (Cincotta, 1989), presents what Vogel et al. (1973) term, “a respiratory dead-space of extraordinary magnitude in which diffusion is inadequate, alone, for gas exchange”.
For this reason, the black-tailed prairie dog has evolved a system of burrowing which creates a system of wind-induced ventilation within the burrow. The burrow of the black-tailed prairie dog has an opening at both ends and mounds of earth at each end, of different sizes at each end, one taller than the other, and each mound being up to 1m in height and 2.5m in diameter (Cincotta, 1989). When a breeze hits the mounds, air enters the burrow through the lower mound and leaves through the end with the higher mound. This system of wind flow has been independently verified in wind tunnel experiments, with wind-flow within the burrow being a linear function of wind flow across the mounds.
Interestingly, not only has the burrowing system of the black-tailed prairie dog been found to be an excellent example of wind-induced ventilation directly from nature, but the architecture of the burrows of the black-tailed prairie dogs encourages increased species diversity of arthropods (Bangert and Slobodchikoff, 2006). Later work (Cincotta, 1989) found that adequate airflow through the burrow can be generated with only one mound, and the presence of the second mound has been explained by various hypotheses, such as the prevention of predation (through its use as a look-out post), or the prevention of flooding. Cincotta (1989) argues that the two mounds (which are usually found shaped one as a dome and one as a crater) actually represent functionally identical structures that have simply been built under different constraints in transport costs (i.e., different costs of energy). Thus, the ventilation model of Vogel et al. (1973) does not, concludes Cincotta (1989) provide a fully adequate model of the observed mound construction, and including energetic parsimony within the equation explains why the prairie dogs build the two mounds (i.e., although only one mound is needed for the wind-induced ventilation system to work, it is an energy-saving measure, in such a long burrow, to remove earth from both ends of the burrow).
Similarly to how supplemented straw is used to stabilize the soils used in adobe brick construction, the mounds of the black-tailed prairie dogs are stabilized with plant fibers found in the topsoil near the entrances to the burrows (McHenry and May, 1984). Using plant fibres in mixture with the excavated soils allows the black-tailed prairie dogs to build vertically and to use less energy (as less excavated soil is needed), replicating similar energy-saving practices in building adobe brick buildings (Boudreau, 1971).
Section 2.2: Other notable investigations
Nature has provided engineers and architects with many examples of sustainable technologies. Animals do not have to resort to damaging the environment to be able to survive within their habitat; they fit, harmoniously, within that habitat, in balance with the physical conditions and with the other species that share the same habitat. This section will discuss some other examples, from nature, of how animals have evolved to cope with their surroundings in an optimal manner.
The mud shrimp, Callianassa truncata, has been studied in the Tyrrhenian Sea and has been found to produce complex cones and burrow systems which affect the physical structure of the sea bed, and, concomitantly, the chemical zonations and the exchange processes across the sediment-water interface (Ziebis et al., 1996a; Boudreau, 1994). The mud shrimp builds these cones, therefore, to modify their immediate micro-environment by forming chemical links between the sea and the sediment. Adjacent to each cone is a shallow depression which acts to funnel water in to the cone system, and which means that oxygen, instead of penetrating only a few millimeters in to the sea bed, actually penetrates more than 50cm down, allowing oxygen-breathing animals to live in the holes (Ziebis et al., 1996a).
The cones that are built by the mud shrimps are outlets for the tunnels, re-routing ammonia from buried sediment to the water above; this ammonia flow helps to nourish the sea water, providing more nourishment for phytoplankton, for example, and so the entire food chain benefits from the cone-building of the mud shrimp (Ziebis et al., 1996a). Similarly to how the complex architecture of the black-tailed prairie dogs provides opportunities for increased species diversity, the cone-building habits of the mud shrimp provides greater nourishment for those species that share its habitat. As Ziebis (1996a) herself stated, “it is a source of wonder that these relatively small animals can build such complex burrow structures and complex architecture”.
Zeibis et al. (1996b) concluded, therefore, that the complex cone and burrow systems of the mud shrimp alters the small-scale flow regime, altering the shrimps own micro-habitat whilst also providing benefits to the wider community, so much so that it was concluded that, “the high spatial and temporal variability of oxygen distribution in a coastal sea bed depends on sediment surface topography (as formed by Callianassa truncata)” and the concomitant changes in boundary layer flow velocity and sediment permeability.
Takegaki and Nakazono (2000) examined the role of the mounds in promoting water exchange in the egg tendering burrows of the goby Valencennea longippinis. Valencennea longippinis spawns in burrows and after spawning, the female constructs a mound on top of the burrow by piling up materials derived from the substratum. Experiments by Takegaki and Nakazono (2000) showed that the mounds promote water-exchange in the burrow allowing the exchange of oxygenated sea water to the developing gobies within the burrow, with dissolved oxygen concentrations being much higher in burrows with a mound than in burrows without a mound. The construction of a mound on top of the developing eggs thus not only protects the eggs from potential predators but also has an important role to play in delivering oxygen to the developing gobies within the burrow.
These are but two further examples of how nature has evolved practical, sustainable, solutions to the problems presented by the immediate environment. The solutions formed can be extremely useful to engineers and architects who are wanting to design buildings on sustainable principles. As Thomas Herzog states in his book Architectural Design’s Green Questionnaire, “In general I do not think that architecture can be deduced immediately from nature, since the design process and functions of our buildings are quite different from what is found in most plants and animals. Nevertheless, there are a lot of lessons to be learnt from nature, especially with regards to the efficiency, performance, adaptability, variety and tremendous beauty which most organisms display under close observation. Considering that nature has to obey the same physical laws as man-made objects this should be seen as very encouraging for us, making it well worthwhile to study its principles and mechanisms”.
Chapter 3: Examples of Buildings that incorporate sustainable features derived from natural examples
This Chapter presents some examples of buildings that have applied solutions found from Nature to provide sustainable living spaces. Examples include, amongst others, several buildings designed by Eugene Tsui, such as the residence of Florence and William Tsui in Berkeley, California, the Watsu School at Harbin Hot Springs, the Exposition Building for the International Celebration of Innovation and the Tsui Design and Research Inc. Headquarters in Emeryville, California, and the the Kanak Cultural Centre in Noumea, New Caledonia designed by Renzo Piano.
The residence of Florence and William Tsui in Berkeley, California, designed by Eugene Tsui, is based, in its entirety on the tardigrade, which is known to be one of the world’s ‘most durable’ animals and which has systems inbuilt to ensure protection against flooding, fire and termite attack, amongst other things (Tsui, 2007). The house is fitted with a solar heating system and with a natural ventilation system that keeps it cool in summer and warm in the cooler months (Tsui, 2007). The house is, essentially, a living system that is capable of actively responding to any external conditions, with water systems in place that are designed to provide cooling and heating and which were based on the capillary structures of dinosaur species which allowed dinosaurs to regulate their own body temperatures (Tsui, 2007).
The Florence and William Tsui residence is a notable application of the Bernoulli Principle, as it employs the Bernoulli effect in adjustable vents, which not only draw in fresh air, without the requirement for mechanical power, but also provide natural light and claimed to be inexpensive to apply (Tsui, 2007). Nostril windows pull out from the wall to let air in, using the Bernoulli effect, where air is sucked in through the open shaft and through the screened tube, which lets air in and keeps insects out. (Tsui, 2007) Tsui notes in his book Evolutionary Architecture, Nature as a Basis for Design that this facet of the design of this building was inspired by such natural examples as the prairie dog burrows.
Also designed by Eugene Tsui, the Watsu School at Harbin Hot Springs is, again, a totally sustainable building, with solar-powered panels and movements of cold water around the building allowing for the natural ventilation of the building. The spherical shape of the buildings also allows for wind flow to cool the buildings, as a whole. The Tsui Design and Research Inc. Headquarters in Emeryville, California, another Eugene Tsui design, is also a totally sustainable building, incorporating natural ventilation systems based on the prairie dog burrows; the building is totally self-sufficient and uses plant life for interior temperature control, with a retractable roof allowing for the entrance of cool air, if necessary. Water is collected from the roof and used for all of the buildings needs; the integrated water system is seen, by Eugene Tsui, as an example of architecture as a living organism.
Another architect whose interest lies in evolutionary, or, better, ‘organic’ architecture is Renzo Piano who designed the Kanak Cultural Centre in Noumea, New Caledonia. This building is a synthesis of nature and technology, reflecting the Kanak people’s understanding of the harmony of life and of Nature. As Piano states, “ (I wanted)…an architecture that genuinely expresses itself between the assertion of the old, reliable values and the exploration of the new in the spirit of time” (Young, 2007). Piano’s aim for the building was to present an architectural masterpiece based on “finding the gestait” of the Kanak people and the site, through a full understanding of the Kanak people, their history and cultural traditions (Young, 2007).
Aside from showing cultural respect in the design and form of designing this building, and thus fitting in to its intended environment well, the Kanak Cultural Centre in Noumea, New Caledonia also shows a wide range of natural ventilation systems. The façade of the building is a double skin which provides a large air space between the woodwork and the galleries, forming a stack effect which, during the day, means hot air rises out of the space while cool air is drawn in to replace it; the cooler air then passes around the building at lower elevations, flowing out towards the lagoon at the side of the building (Young, 2007); in this way, the building ‘breathes’ with its environment, as a function of the environment in which it sits. Skylights set in the roof of the building allow for the entry of cool air, as necessary, and the interaction of all these ventilation systems allows the building to “find a continuous balance with Nature” (Young, 2007).
Examples such as these buildings, and others that could be mentioned, show how it is possible to study Nature and to study the solutions provided by the process of natural selection over many generations, to enlighten sustainable building projects. That buildings can be built, for only slightly more cost than non-sustainable buildings, to act in harmony with Nature and to produce architecture that acts as a living organism is a beautiful vision. This vision of Tsui’s, as presented in his book Evolutionary Architecture, Nature as a Basis for Design, and in his many other writings, speeches and in his designs for, and his actual buildings is a beautiful vision, of mankind being given the ability to live in concert, not antagonistically with, Nature.
As has to be realized, however, whilst Nature can be used as inspiration, the implications of scale need to be considered, in terms of the fact that solutions from Nature cannot simply be scaled-up in order to suit the particular needs of the built environment. The solutions need to be tailored, according to the particular situation, within the particular knowledge of the architect, as the implications of scale have a significant impact on the actual design of a building. Due to the implications of scale, solutions from Nature can never be directly copied, but need to be adapted as necessary to the particular situation in hand. The Bernoulli Principle and the Venturi effect can, however, when implemented successfully, be used to great effect in terms of producing architecture that is at once beautiful and fully at harmony with Nature, as a ‘living organism’ as in Tsui’s vision of evolutionary architecture.
Chapter 4: Conclusions
Green Architecture is the major architectural movement of our time. As has been seen, the ecological damage caused by buildings (through their heating and air conditioning systems, for example, or their use of unsustainable materials) can be recorded in real figures, in terms of the amount of carbon dioxide a building produces in terms of how much a building contributes to global warming. As has been seen, there are many pressures on architects, and on the construction industry as a whole, to produce sustainable buildings. This will only continue to increase in the future and so architects, such as Eugene Tsui, with their visions of buildings as living organisms, living and breathing in harmony with their environment are not so far-fetched. Mankind has become detached from his surroundings, and this detachment has meant that the Earth, and its natural systems have been abused, almost to the point of no return. As has been shown in this dissertation, the process of natural selection has led animals to find, over evolutionary time, sustainable solutions to problems that the environment presents to them. Evolutionary architecture, as Tsui labels his brand of architecture, is an attempt to recreate this harmony and to offer to mankind a different vision of the built world.
Studying natural phenomena, such as the burrows of the black-tailed prairie dog, Cynomys ludovicianus, the complex burrow and cone system of the mud shrimp Callianassa truncata and the burrow-mound system of the goby Valencennea longippinis which allows for increased gas exchange to the developing eggs in the burrow, as has been conducted in this dissertation allows architects to ‘think outside the box’ and to find alternative solutions to designing in a sustainable manner. This dissertation has aimed to show how looking to Nature can provide sustainable building solutions, using the particular example of wind-induced natural ventilation. That many of the natural solutions to this problem have been successfully incorporated in to many buildings, as discussed in Chapter 3 (i.e., the residence of Florence and William Tsui in Berkeley, California, the Watsu School at Harbin Hot Springs, the Exposition Building for the International Celebration of Innovation and the Tsui Design and Research Inc. Headquarters in Emeryville, California, and the the Kanak Cultural Centre in Noumea, New Caledonia designed by Renzo Piano), shows that the idea of adapting solutions from Nature is workable, if only we can take
