Bsc (Hons) Dissertation

Justifying Vegetation as a Primary Technology in Future Urban Environmental Sustainability

By Marcus Fisher 33308430

Submitted in partial fulfillment of the requirements for the degree BSc(Hons) Building Surveying Leeds Metropolitan University Month year

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Abstract Historically the expansion of the urban condition, from the first post hunter gatherer agricultural settlements to the mega cities of the pacific rim has been a reflection of the success of urbanism in stimulating anthropocentric led change, opportunity, invention and diversity. Examined through this particular lens, it is hard to argue that the process of urbanisation has not been a good thing.

However, the rapid expansion of urban areas in the 20th C and the consequent exponential increase in the consumption of non-renewable resources and the separation of producers and consumers has raised questions as to the future of this process.

As this relationship between urbanism and its operation has been increasingly put under examination, it is now understood that the world, if considered as a composite ecosystem, which contains an intricate network of sub systems cannot sustain the impact of this process. The concept of sustainability and the need to respond to these changes has raised a number of issues in respect of the unstoppable territorialising of the land as urban and the destruction or weakening of these ecosystems beyond the point of sustainable recovery.

The dilemma that this raises has created opportunities for rethinking the relationship between built form and a way of achieving a sustainable structure to existing and future expanding urban areas. This would create the potential for a symbiotic link between the quality of the urban environment and its consumption of resources. Although there has been a positive change in reducing resource use, becoming more efficient in resource consumption, recycling and providing advanced technology to mitigate the impact of the urban environment, these operations still consume energy and create secondary pollution. Equally none of these provide an integrated approach in addressing the key problems that the urban environment has created in terms of environmental quality, reconnection with the network of the world’s ecosystems and energy reduction.

The use of vegetation at a scale that extends from internal to external building envelope and eventually to generic urban scale offers an opportunity for addressing this issue as an integrated approach. Although the science of this process is still in its infancy and politically it is not universally accepted as a realistic alternative, there is enough research to support the use of vegetation as a primary technology in addressing key issues of environmental sustainability.

This study through the interpolation and coordination of various published research justifies the potential of vegetation as a holistic technology. This approach is not anti urban, does not try to recreate a “rus in urbe”, but reflects the undeniable trajectory of urban expansion. The justification rests on creating new interconnected system in which vegetation is placed at the centre of the environmental process and incorporates the requirements of the

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anthropocentric within a reformed sub set of eco systems, which support micro to macro scale urban environmental sustainability.

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Table of Contents Chapter One Problem Speciation……………………………………………………………………1 Literature Review………………………………………………………………………5 Methodology…………………………………………………………………………..11

Chapter Two Urbanisation…………………………………………………………………………..13

Chapter Three Sustainable Ecological Context…………………………………………………….17 Chapter Four: The Use of Vegetation in the Internal Building Envelope Indoor Air Quality (IAQ)……………………………………………………………...21 Improving Indoor Air Quality with Vegetation………………………………..........21 Ventilation……………………………………………………………………………..23 Improving Ventilation With Vegetation...............................................................24 Interior Noise Pollution.......................................................................................26 Reducing Interior Noise Pollution With Vegetation……………………………….26 Interior Air Temperature and Humidity……………………………………………..29 Cooling a Building by Shading With Vegetation…………………………………..29 Regulating Interior Air Temperature and Humidity with Vegetation…………….31 Other Health and Wellbeing Benefits………………………………………………31 Chapter Five: The Use of Vegetation on the Exterior Envelope.

Heat Exchange……………………………………………………………………….33 Material Longevity……………………………………………………………………34 Air Quality……………………………………………………………………………..34 Air Flow Around Buildings………………………………………………………......36 Vegetation as a Mitigating Technique…………………………………………......37 Plant Processes………………………………………………………………….......37 Vegetated Roof Systems……………………………………………………………38 Vegetated Walls……………………………………………………………………...43 Chapter Six: The use of vegetation at the Urban Scale Urban Heat Islands…………………………………………………………………..49 Air Quality……………………………………………………………………………..50 Airflow in Urban Environments…………………………………………………......52 Noise Pollution…………………………………………………………………….....53 Vegetation as a Mitigating Technique……………………………………………..55 Large Scale Use of vegetated Roof and Wall Systems………………………....55 Urban Forestry……………………………………………………………………….58 Biodiversity…………………………………………………………………………...62 Perception…………………………………………………………………………....62 A Holistic Approach………………………………………………………………....62

Chapter Seven Conclusion…………………………………………………………………………...64 Recommendations……………………………………………………………….....66

Bibliography Bibliography………………………………………………………………………....68 Bibliography of Illustrations and Diagrams……………………………………….81

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Appendix One: Plant Processes Photosynthesis……………………………………………………………………..84 Evapotranspiration…………………………………………………………………87 Shading…………………………………………………………………………......90 Dry Deposition…………………………………………………………………......92 Phytoremediation……………………………………………………………….....94 Vegetation Attenuating Noise Pollution………………………………………....97 Vegetation Affecting Air Flow…………………………………………………….99 Appendix Two: Case Studies LOG ID Architects, BGW, Dresden, Germany………………………………...100 Peter Costa (1995) An investigation into the Potential Benefits of Using Interior Vegetation as a Means to Reduce Noise Pollution…………………………...104 The Osher Living Roof, California Academy of Sciences, San Francisco….106 A Comparative Study of the Thermal Performance of Vegetation on Building Surfaces……………………………………………………………………………111 Ken Yeang (2007) Solaris Towers, SIngapore, Malayasia………………......113 Buenos Aires Urban Heat Island: Intensity and Environmental Impact….....118 The Impact of Shelterbelt Trees on Heating-energy Reduction……………..122 A City in a Garden, Singapore…………………………………………………..129

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List of Illustrations and Diagrams Figure 1. World population growth (billions) 1050-2050.

Figure 2 . Atmospheric CO2 Concentrations and Average temperature over past 1000 years.

Figure 3. Percentage of urban and rural population 1950-2050 Figure 4. Air filtering climibing and trailing plants.

Figure 5. Desktop air filtering vegetation.

Figure 6. BGW building, main atrium.

Figure 7. BGW building, multi-level vegetation.

Figure 8. Alterra Laboratory, Natural ventilation.

Figure 9. Vegetated ventilation.

Figure 10. Alterra Laboratory, energy and ventilation concept.

Figure 11. Trgy Insurance building, Planted lift shaft, vegetated panels installed to reduce noise.

Figure 12. Noise reducing vegetated column.

Figure 13. Noise reducing vegetated wall.

Figure 14. GCC, Herten front façade.

Figure 15. Building and vegetation plan.

Figure 16. Vegetated wall provides perfect acoustic quality.

Figure 17. Ficus Benjamina providing shade.

Figure 18. Large trees providing shade.

Figure 19 & 20. Musa Sapienta (Banana tree) providing shade.

Figure 21 & 22. Vegetation regulating temperature and humidity in a social greenhouse.

Figure 23. Interior vegetated landscape providing a regulated and tranquil environment.

Figure 24. Earths reflective coefficient (Albedo).

Figure 25. Albedo values for various types of planet surface.

Figure 26. Air pollutants, sources and effects.

Figure 27. a) Isolated roughness flow, b) Wake interference flow, c) Skimming flow.

Figure 28. Flow around a tall building, with lower buildings upwind.

Figure 29. Hanging gardens of Babylon.

Figure 30. Extensive green roof, Vancouver, Convention Centre, Canada.

Figure 31. Intensive green roof, ACROS building, Japan.

Figure 32. Typical elemental composition of a vegetated roof.

Figure 33. Interior/exterior heat exchange, traditional and green roof comparison.

Figure 34. The Osher living roof, California Academy of Science.

Figure 35 & 36. Extensive green roof, 900 North, Michigan Avenue, Chicago.

Figure 38. Structural differences in vegetated walls.

Figure 39. Structural differences in living walls.

Figure 40. Classification of vertical greening principles.

Figure 41. Extensive living wall, Vancouver, Canada.

Figure 42 & 43. Vegetated façade and thermal image showing temperature difference.

Figure 44. Sulphur Dioxide concentrations across exposed and vegetated facades.

Figure 45. The Urban Heat Island, sources, process and effects at meso and micro scales.

Figure 46. Acid rain process and effects.

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Figure 47. Urban smog, Los Angeles.

Figure 48. Urban air flows. a) Boundary Layer, b) Rural layer, showing mixed surface roughness.

Figure 49. Pressure and Decibel levels of anthropogenic noise pollution.

Figure 50. Comparison of infiltration percentage of natural and impervious ground cover.

Figure 51. Principal contaminants of urban runoff.

Figure 52 & 53. Extensive use of vegetated roofs, Stuttgart, Germany.

Figure 54. Urban forest, Portland, Oregon.

Figure 55. Extensive urban forest, Toronto Canada.

Figure 56 & 57. Urban Bioswales.

Figure 58. Constructed urban wetlands, Beijing, China.

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Problem Specification The transformation from a rural to an urban economy makes the process of urbanisation one of the most important global trends of the 21stC (UN Habitat 2012). Cities no longer function as areas designed for settlement, production and services. They now generate the principal influences behind global development, controlling changes in social, political and environmental interactions at every level (DESA 2008). Urbanisation consequently provides the basis and momentum for global change (UN Habitat 2012).

Since the origin of urban settlements 15,000 years ago, the proportion of the population living in urban areas has sustained an exceptional increase. This has contributed directly to problems affecting the use and distribution of resources, the sustainability of the relationship between urban and rural structures, individual and corporate health issues, polarisation of infrastructures and factors affecting the micro, meso and macroclimate (J.L. Weisdorf, 2005).

The expansion of urban areas has been shown to significantly contribute to the effects of global warming and the sustainability of planetary ecosystems.

According to the International Energy Agency, the 20 largest cities in the world are responsible for 80% of the total global energy consumption and generate around 80% of global greenhouse gas emissions (IEA 2012).

Academics have become increasingly aware that humanity’s continued existence on earth is dependent upon an interconnected web of services provided by the earth’s ecosystem. Since the late 1960’s it was realised that the human race could not go on consuming the earths natural resources and altering its biocentric systems at this velocity without thought of mitigating the likely consequences (Meadows et al 1972).

The concept of sustainability emerged through a dialogue between ecologists and political planners, which attempted to find a consensus on how the environment and economy should be managed (W.M. Adams, 2001).

The definition described in the United Nations Brundtland Commission which refers to development that enables us to meet our present needs without

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denying future generations with the means to meet their own needs, represents the ideal of economic and technological development, time and futurity and the ethical notion that the rights of future generations have to a similar opportunity as ourselves. The consumption of natural resources and the degradation of the environmental condition indicate two essential elements for consideration with regards to sustainable development. However, whilst these factors are easily recognised, it is far more difficult to implement them (WCED 1987).

The key issue in sustainable urban development is the need for a relationship or balance between environmental health and economic growth. As more people move to urban areas, pressure is increased to provide public services, infrastructure, homes and employment. The rising demand results in the rapid overuse of energy resources and the degradation of surrounding ecological networks resulting in catastrophic and irreversible levels of anthropogenic interference with the environment (J. R. Short, 2012). With rapid urbanisation continuing to have an impact at a global scale, the need for alternative solutions to provide an answer to the effects it has on the planet and to ultimately achieve a more sustainable ecosystem is a global problem of major importance (UNFCCC, 2007).

The construction industry is one of the most resource-intensive and environmentally damaging industries in the world. The use of fossil-fuel-derived energy in the production of materials and transportation contributes to the consumption of around 40 % of the global energy use and 50 % or 40 million tonnes of the annual global greenhouse gas emissions. It is apparent that there is an undeniable link between global urbanisation and environmental degradation, thus providing a reason to necessitate changes in the construction process and in the structure and form of the urban model to achieve a more sustainable urban environment.

The focus on environmental protection has become a global issue, including a great deal of investment in renewable energy such as wind, solar and hydroelectric power. The construction industry has implemented sustainable building measures that are environmentally friendly and resource-efficient

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throughout a building's life: including its design and construction phase and also its operation, maintenance, renovation, and demolition (J.O. Lewis, 1999).

Bioclimatic architecture is the design of the interior and exterior of buildings with regards to the local climate (O.M. Vasquez, 2009). Its main aims are to provide thermal and visual comfort through the use of natural resources. The basic attributes of bioclimatic architecture are passive solar systems for example the use of sunlight, air, wind, vegetation, water and soil which are incorporated onto, into and around buildings for various sustainable services such as heating, cooling and lighting (J.O. Lewis, 1999).

Bioclimatic architecture covers a large range of alternative resources and technologies that can be integrated into the building and its services to create a more sustainable structure. Many alternative technologies being used today, such as solar photovoltaic panels and ground source heat pumps generate more sustainable means of creating energy, however for the purpose of this research this study will specify how the use of vegetation within and around the building envelope and also in large scale urban areas can passively ultilise the natural energy that already exists, as a means of solving this issue (O.M. Vasquez, 2009, J.O. Lewis, 1999).

Vegetation covers around 20% of the earths surface and is one of the single most important factors contributing to life on earth; it is a key component of the ecosystem we live in today and, as such, is involved in the regulation of various biogeochemical cycles which control our environment and allow us to function as humans (J.M. Adams 1997, E.P. Odum 1997). Vegetation is the foundation of life on earth but its relationship with anthropocentric activity has somewhat deteriorated due to humanity’s preoccupation to control nature’s resources and systems in pursuit of economic growth (K. Yeang, 2007).

Research into the use of vegetation as an environmental technology has shown that the natural properties that it possesses can have a regulating effect on the issues related to urban areas such as: Air quality, temperature, humidity, pollution, noise, the urban heat island effect and the general notion of creating more sustainable cities (M. Santamouris, 2001, M. Hough, 1995). Consequently

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the use of vegetation as an alternative technology in the urban condition is an important opportunity for rejuvenating the link between humans and ecological systems and therefore improving the conditions of sustainability within our urban environment.

The aim of this dissertation is therefore to place future urban growth in the context of a sustainable agenda, which investigates the use of vegetation in the internal building environment, its envelope and large-scale urban morphology. It will determine whether the integration of vegetation as primary technology is a viable option both as a long term and short-term technique in supporting sustainable urban development.

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Literature Review Addressing issues of sustainability in the urban environment at a macro scale has generated a range of theoretical positions, which could have a degree of legitimacy in informing future policy. Equally the need to address specific issues at “the street level” has generated a plethora of pragmatic opportunities, which have potential currency at local, glocal and global scales.

Although the literature review has the possibility to cover a wide variety of theories and opinions on sustainability, for the purpose of this dissertation the review will focus on the use of vegetation in the built environment. Although the literature presents this approach in a variety of contexts, the dissertation will primarily focus on their application as part of improving sustainability in urban systems, through site based interventions from the building envelope to generic urban form.

The proposal for utilising vegetation as a key element in urban environmental sustainability has its origins in the processes of urbanisation and the collateral damage, which destroyed the balance of ecological relationships between anthropocentric and biocentric activities. Therefore to understand the effects of this broken relationship the investigation will commence with a review of literature on the origins and history of urbanisation.

The foundations of urbanisation can be traced back to the transitional period from hunter-gatherer to sedentary agricultural communities, known as the Neolithic revolution, first expressed in 1923 by Vere Gordon Childe (J.L. Weisdorf, 2005). There has been a vast amount of conjecture by various historical and academic bodies into the reasons for the development of global agricultural communities (the precursor to permanent settlement); such theories include climate change, the appropriation of political power, intentional evolution and demographic change (D.A. Bainbridge, 2005). However, the only commonly established explanation of this transition seems to be that no single explanation proposed so far is entirely adequate (J.L. Weisdorf, 2005).

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Although the excessive use of differing theories provide no single explanation, carbon dating has produced scientific evidence of this transition and of the global scale of this occurrence from Asia to Europe (C. Paik 2010). One principal view, which is widely expressed and agreed within scientific and academic groups, suggests that the rise of agricultural communities during this period had a fundamental influence on later economic development and expansion of urban areas. For example Galor and Moav (2002) suggest that the transition into agricultural communities magnified the potential evolutionary advantage of individuals within these communities, which in turn stimulated concentrated economic and technological growth. (Galor and Moav, 2002) The Neolithic revolution created the conditions for concentrations of population, domestication of livestock and a network of static habitation. The Industrial Revolution acted as a further catalyst and formed the structure for the modern urban system. Although it was a primary facilitator of advanced urban systems, the consequences of the scale of change created many disadvantages, including social segregation, economic division and in terms of the relevance of this study, environmental degradation.

The study of this phenomenon led to a huge amount of both supporting and opposing literature with relation to its impact on biocentric/anthropocentric relationships and the implied consequential damage to ecological communities.

Dutt et al., (2003) associates urbanisation in this period to improving the standard of living, increasing life expectancy, and providing huge employment opportunities. However other researchers neglect this achievement and focus on the industrial revolution having a fundamental impact on the environment creating complex links between the two (R. Sanchez-Rodriguez et al., 2005).

Although there are differing views on the future of urban expansion most commentators view this process as a symbol of anthropocentric progress. As Ling (2005) indicates that cities are instruments of rapid economic growth. This polemic is supported by a large body of empirical studies into the relationship of economic growth and urban expansion (F. Fay, C. Opal,1999, D. Henderson, 2001).

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However, urban areas can also pose major threats to the achievement of sustainable development, due to detrimental environmental impacts and the other adverse effects associated with intensive resource consumption and poor management (DFID, 2002). Although some theorists dispute this such as Stewart Brand in his book Whole Earth Discipline, (2009) which argues that urbanisation can primarily have a positive impact on the environment such as, the migration away from rural areas reducing the use of destructive subsistence farming techniques such as slash and burn agriculture (Stewart Brand 2009).

One method of understanding the process of urbanisation is the way rural areas acquire urban characteristics (T. Tryzna, 2007). Literature such as that by Landsberg (1981) has demonstrated the direct link between urbanisation and environmental degradation of existing ecological systems, thus providing the impetus to question the positive aspects of urban growth in the context of measures of environmental quality (H.E. Landsberg, 1981).

Climatic changes in urban areas have been recognised since the industrial revolution (L. Howard, 1833). The rapid expansion of modern urban areas has created distinct changes in land topography, facilitating atmospheric and environmentally degrading phenomena. (H.E. Landsberg, 1981).

After the inconclusive views on environmental and social issues expressed by Malthaus and Mill (1798) and the creation of the scientific subject of ecology (E. Warming), there followed a period of economic and industrial expansion during 1700-1800’s. However very little influential information on the awareness of environmental issues was published until the early 20thcentury where the discussion into humanity’s uncertain future became prominent (R. Carson, 1962).

During the 1960’s a consensus arose that the humanity could not continue consuming the earth’s natural resources at the current rate, without consideration of the detrimental effects this would have on the environment.

This line of thought was expressed some time later by Meadows et al in The Limits to Growth (1972), which echoes some of the concerns and predictions of Malthus (1798) in his essay on the Principle of Population. This particular

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prediction was deemed to be overly pessimistic and based on poor quality data (R.M. Solow, 1972). In The Skeptical Environmentalist, Bjørn Lomborg (2001) paints a completely different picture demonstrating that there is no threat of a global energy crisis (B. Lomborg, 2001). However other influential theorists and scientists such as Trainer, Grubb and Meyer (1995) supported Meadows theory.

Nonetheless these views and opinions stimulated a vast reservoir of research and sub theories, establishing possibly the most influential concept in the modern world (T. Trainer, M. Grubb G. Meyer, 1995).

The key report to emerge from this earlier discourse, Our Common Future published by the UN’s World Commission on Environment and Development (1987) created the concept of sustainable development, which cleverly encompassed global and local problems and set a precedent for the emergence of a range of solutions. This inclusive theory of sustainable development prompted a tremendous expansion of literature on environmental, economic and social theories and has been subject to controversy since its publication.

(WCED, 1987). Jacobs (1999) believes the definition is to lax, lacking in credibility, Beckerman (1995) supports this referring to sustainable development as a cautionary principle fashioned by environmentalists.

Realising the concept of sustainable urban areas has created a congregation of various players in the development process, one of which, most relevant to this dissertation is that of ecologists.

James Lovelock’s Gaia hypothesis most noticeably presents this view, proposing that natural organisms coexist with their inorganic environs on Earth to create a self-sustaining bionetwork contributing to the maintenance of conditions for all planetary habitation (J. Lovelock, 1972). Although this hypothesis was initially neglected and criticised, for example Stephen Jay Gould (1997) demonstrated it as a simple descriptive metaphor of planetary processes lacking credibility, later revisions have now firmly embraced its concepts, influencing disciplines such as, biogeochemistry, systems ecology, and climate science (J. Lovelock 1972, S.J. Gould, 1997).

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Theories such as this have been adapted in terms of applying the functions of sustainable ecosystems within urban areas, for example through the practice of Ken Yeang. His recent work has investigated the concept of 'ecomimicry', referring to the design of the anthropocentric built environment which imitates the processes, structure and properties of ecosystems, such as biological structure, materials recycling and increasing efficient energy use (K. Yeang, 2007).

Despite a historical lack of documentation the role and context of vegetation in the urban form has a long history. During the early twentieth century studies by De Rudder & Linke (1940) documented the flora and fauna of urban areas.

More recently publications including that of the US Environmental Protection Agency (EPA) presented by Daplito Dunn and Stoner (2007) assertively indicated the natural advantages of vegetative infrastructure, confirming that its use offers a way of balancing the environmental deficits caused by anthropogenic activity. This was interpreted, as a key element of re-evaluation as prior to this, vegetative infrastructure was described principally in terms of conservation.

Following this, research into applying the natural plant processes into the built environment have been thoroughly expressed at different mediums for example within the interior building envelope scientific researchers such as Wolverton (1984), Lohr & Peason-Mims (1996) an Burchett (2001) have demonstrated the relevance for human health and interior climate. Following the 6th international conference on indoor air quality, ventilation and energy conservation in buildings, M. Burchett et al’s. (2001) influential paper expressed the application of interior vegetation as becoming a standard technology in achieving sustainable operation. At the exterior scale the quantity of research and publications focused on the application of vegetation to the building façade has been increased in recent years, for example research done by that of Köhler has provided the relevant information for green walls in particular, to be applied as an environmental regulator of urban climate (M. Köhler, 2008). At an urban scale, the garden-city movement at the beginning of the 1900’s may be seen as one of the first ecological responses to industrialisation in urban areas (F.

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Kaltenbach, 2008). In additioion, the garden in a city project, Singapore can be seen as a present day functional model of large-scale vegetative integration.

Exterior Vegetation has been used for centuries as a medium to give a green appearance to the urban environment (N. Dunnett, N. Kingsbury, 2006).

However, the effect of urban greening in the context of its functional capacities in order to mitigate environmental impacts of urbanisartion has only recently been researched, therefore it is lacking in hard data and applied evidence.

Furthermore, research in this field can only be specifically applied to one medium i.e. interior/ exterior, little research has be done with a holistic approach to the large-scale integration of vegetation across all mediums. One of the problems contributing to this lack of data has emerged from the time it takes vegetation to have a noticeable effect, however principally the main weakness within this field is the weight of research (M. Ottele, 2011).

From the evidence presented by recent research into the integration of vegetation as a primary technology in contributing to urban environmental sustainability, this dissertation will act as a cross disciplinary medium, drawing together elements of research across all areas in order to justify the use of vegetation and its holistic use across urban expanses.

In conclusion an outline of the hypothesis is as follows: The use of vegetation as a medium and long-term component of the urban condition can at the human scale increase comfort, create healthy working and living conditions and potentially improve economic productivity. At the meso scale it can improve long term building performance, reducing energy inputs and extending building life cycles. At the generic scale vegetation can create an alternative sustainable urban morphology, which is symbiotic with anthropocentric processes and systems.

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Methodology Humans are not separate from nature but are part of nature. Anthropocentric and biocentric systems are intimately reliant on each other. As a means of finding a dynamic balance in urban structures, vegetation must play a major role in mediating the development of the future urban structure, not to recreate nature but to enhance a comprehensive sustainability of the urban conditions.

The context of this dissertation will be unique in that it will draw together and act as a cross-disciplinary medium for subjects that have contrasting academic and applied conditions. The approach combines theoretical discourse on urban spatial planning and urban design with the applied mediums of health, construction, landscape architecture and horticulture. This fusion of different disciplines creates the opportunity for multi-layered connections as a proposal for an alternative model of sustainable urbanism.

In order to justify the role of vegetation as a primary technology in urban environmental sustainability, there will first be an analysis into the global problem of the urban condition. This will provide a link to an analysis and discussion of the concept and issues of sustainability with reference to the importance of ecological systems and vegetation, applicable to supporting the sustainable operation of current and future urban structures.

The dissertation will analyse the environmental problems resulting from the urban condition in the context of the interior building climate, the exterior building envelope and the overall urban structure. Potential solutions will be examined through the use of vegetation as the primary technology in offering sustainable solutions.

The performance of vegetation as an environmental modifier will be assessed through a conclusion, which evaluates individual properties and contextualizes them into an overview of their contribution to sustainable urbanism.

For the purpose of this dissertation, research methods will involve the collation of past case studies and scientific experimental data in order to gain a broad Â

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spectrum of ideas, opinions and facts. The case study data will comprise examples of the application of vegetation as a primary technology in the context of interior, exterior and urban mediums in order to justify its potential through existing evidence. Data from scientific experimentation will be used to support the application of vegetation in a quantifiable and factual context. The use of case studies in producing this dissertation will allow a substantial amount of detail to be collected providing a greater depth of data that is not collated in other research.

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Urbanisation is arguably the most complex and important environmental socioeconomic phenomenon of the 20th and 21st centuries. Understood as the substantial and ongoing migration of people from rural to urban settlement, it also represents extensive and irreversible changes in production and consumption and the way people interact with ecological systems (A. Allen, 2009).

There is evidence of permanent settlement, cultivated land and the domestication of animals from India to the Baltic region, dating from around 10, 000 BC. The Neolithic Revolution marked the transition from a lifestyle of mobile groups of hunter-gatherers into sedentary, agricultural societies based in a network of small settlements. There is conflicting evidence of how cities originated but the growth of population and subsequent growth in sedentary farming communities expedited technological and social change, and appeared to be the primary prerequisite in the formation of the first urban centres (J.L. Weisdorf, 2005). The process of sedentary agriculture-driven expansion also generated the first forms of government in these larger settlements as exemplified in India and China (J.P. Bocquet-Appel, 2011).

The expansion of commerce in Europe provided the foundations of the modern urban system, but It was not until the 16thC and the beginning of the European commercial and cultural revolution with the development of capital and international trade, that figures of 50,000 to 100,000 people were recorded (R. Lawton, 2002).

The industrial revolution marked a period of both significant population (Fig. 1) and urban growth during the 19thC, particularly in Western Europe and on a smaller scale in the United States (R. Allen 2009).

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Figure 1. World population growth (billions) 1050-2050.

In 1801, 17% of the population in the UK lived in urban areas, by 1851 the figure had risen to 35% and by 1891 it was 54% (ONS 2012). Large bodies of historical and theoretical research into the expansion of cities demonstrate the influence of the industrial revolution, referred to by Allen (2009) as being, a fundamental factor in the development of the modern city, due to the vast concentration of migrant workers. However the extensive nature and scale of urbanisation during this time period cannot be completely explained by industrialisation alone but rather by a combination of industrial activity and the development of business, technology and commerce, facilitated by advances in infrastructural systems such as steam powered boats and railways (Robert Allen 2009).

While the Industrial Revolution created positive changes for the economic world, it was also one of the primary influences behind today’s issues of environmental degradation. In this period of industrialisation the earths ecological systems were negatively affected by the intensive use of nonrenewable natural resources and extensive changes to the function of the landscape (E. McLamb, 2011). For example Figure 3 shows the sharp increase in atmospheric CO2 levels and temperature during the 1800’s. The ancient symbiotic link, derived from a basic set of needs between humans and nature

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was somewhat destroyed as the shift away from agriculture to urban habitation increased exponentially (J. Lovelock, 2010).

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Figure 2. Atmospheric CO Concentrations and Average temperature over the past 1000 years.

The twentieth century saw the rapid urbanisation of the world’s population as people migrate to city’s from rural areas seeking the economic and social advantages that an urban area provides (Dutt et al 2003). Figure 4 demonstrates the difference between urban and rural flight, the graph shows the global proportion of urban population increased from 29% in 1950 to 49% in 2005. Since urban growth is projected to continue, 60% of the global population is expected to live in cities by 2030.

Figure 3. Percentage of urban and rural population 1950-2050.

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Urbanisation is predominantly viewed as a negative trend, but equally there are positives in improving opportunities for jobs, education, housing, and transportation (L.E. Gaeser, 1998). However, these advantages are far outweighed by the economic issues, increased daily life costs and negative social inequalities that result from mass marginalisation (A. Dunarintu 2012).

The relationship between urbanisation and environmental degradation is undeniable, as the expansion of urban areas means that more land is appropriated to support their infrastructure (F.K. Benfield et al 1999). The expansion of urban areas contributes to the loss of 2% of vegetated land every 10 years, this figure is continuing to rise with the rapidly increasing urban population rates (D. Stanners, P. Bourdeau 1995). A study published by the U.S. Forest Service (2012) showed national results indicating that vegetative cover surrounding urban areas is declining at a rate of around 4,000,000 trees per year (USDA 2012).

Research has shown that a European city comprising a population of around 1,000,000 uses up to 11,500 ton of fossil fuels, 320,000 tons of water and 2000 tons of food whilst also emitting up to 300,000 tons of wastewater, 25,000 tons of C02 and 1,600 tons of general waste per day (D. Stanners, P. Bourdeau 1995). These figures provide a scale model of the trends experienced in urban regions across the world (EIA 2012). The rapid appropriation of vegetated land, energy, fuel, food and water and production of harmful emissions and waste resulting from urbanised areas has shown to significantly contribute to negative environmental effects such as, reductions in air quality through mediums such as pollutant levels and noise, atmospheric temperature increase, and overall destruction of natural ecosystems (EPA 2012).

Urbanisation raises many contentious issues through its economic, social and environmental effects. The collapse of the generic relationship between human activity and ecological systems informs many of the issues previously discussed and highlights the need for the regeneration of ecological systems as a catalyst to maintain and support urban expansion.

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Sustainability can be described as the capacity to endure (FHWA, 2012). The foundations of contemporary thinking on sustainability rely on structuring a dynamic and beneficial relationship between anthropocentric and biocentric systems. Sustainability is thus used to construct and preserve acceptable conditions with relation to economic, social and environmental dimensions, in which humans and nature can coexist within a present and future context (J. Lovelock 2010, WCED, 1987).

The previous chapter acknowledged the requirement for ecological systems to play a key role in future sustainable expansion of the urban form and as such to have the scale and capacity to be robust enough to be self-regulating.

The origins of sustainability were largely influenced by advances in technology, allowing humans to develop a dominance over the natural environment. The 18th and 19thC marked the beginning of a significant period of global human influence categorised as the Anthropocene, in which advancements in technology, science and medicine supported an unprecedented growth of population (R. Wright 2004, A Goudie). Views were expressed as to the negative long-term effects of the Anthropocene during this period of environmental and social disenfachisement (T.R. Malthaus, 1798). Perhaps the most significant movement towards the realisation of these unsustainable processes was research into the relationship between plants and humans and thus the Eugen Warming’s creation of the scientific discipline of ecology (R. J Goodland 1975).

During the 1970’s, the serious nature of the problems resulting from humanity’s reliance on non-renewable energy resources created a global realisation for the need to respond to the environmental degradation. In parallel with the economic repercussions, globally and individually, the concept of becoming sustainable in terms of reducing the negative way humans act upon the environment became prominent in academic and then political forums (Meadows et al, 1972).

In the report Our Common Future (1987) following the United Nations World Commission on Environment and Development, recommendations were made into the way that countries address demands for environmental protection and

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economic development (WCED 1987). In the report Gro Harlem Brutland suggested the concept of sustainable development, defined as “ development that meets the needs of the present without compromising the ability of future generations to meet their needs” (WCED, 1987 pp. 43). In 1992 following a significant increase in demands for environmental protection and spurred by the introduction of the concept of sustainable development, the United Nations Conference on Environment and Development in Rio commissioned Agenda 21, the benchmark for global support into the creation of a more sustainable environment. (UNEP, 1992) The plethora of reports and ever increasing awareness into sustainable development in the late 1900’s stimulated investment into renewable energy resources, recycling and reuse of materials and an overall reduction in consumption in the developed world (F. Dodds et al 2012).

According to the United Nations Framework Convention on Climate Change (UNFCCC), the direct cause of global deforestation is agriculture, being responsible for around 80% of global deforestation, with logging and fuel wood removal also significantly contributing to this percentage. (UNFCCC 2007).

Tropical forest deforestation is responsible for contributing approximately 20% of the world’s greenhouse gas emissions influencing the planets atmospheric and hydrological systems (Greenpeace, 2013). For example The Congo basin contains the second the largest rainforest in the world, embodying 18% of the planets remaining tropical vegetation. The surface areas of such forests are aerodynamically rough which increases air turbulence above them, thus affecting wind patterns. Each hectare of forest releases around 190,000 litres of water as vapour a year. The high exchange of energy and moisture combined with strong winds causes local weather to be circulated in the atmosphere on a global scale (RainforestFoundation 2007). Deforestation can be directly linked to urban expansion as it affects diet (increase in meat consumption), a general increase in food, fuel and materials consumption for those living in urban areas (UNFCCC 2007).

The construction industry is one of the most resource intensive and environmentally damaging industries in the world, consuming around 40 % of global energy production and contributing to around 50 % or 40,000,000ton of

25

annual global greenhouse gas emissions (C.J. Kibert, G.Bradley 2002). The combination of the direct and indirect negative environmental effects of agriculture and construction and their impact on the growth of urban areas creates an imperative for minimising environmental damage by urban expansion and utilising passive technologies to reduce consumption to sustainable levels.

Sustainability is a controversial issue but it is hard to ignore the vast amount of factual information on the negative environmental impacts, created by human activity. It has only recently that renewable technologies and sustainable construction methods have received necessary investment economically and politically. These technologies although advantageous in creating a more sustainable environment, are still resource heavy in their genesis and still neglect the vital symbiosis between humans and biocentric ecosystems (J. Blewitt, 2008).

An ecosystem can be described as a biological community of interacting organisms and their physical environment (Oxford English Dictionary 2013).

Ecosystems comprise the physical and chemical components that provide a support system for the range of organisms living within them including human life. Vegetation plays a fundamental role in the structure and function of all ecosystems, as the primary foundation of food chains, delivering energy, fuel and building materials on which the processes of life depend (E.P. Odum, 1971).

Vegetation is associated with a multitude of direct products such as food, timber and biomass fuel and intangible processes such as photosynthesis and evapotranspiration (Appendix 1.1, 1.2) that indirectly support and regulate our environment thus sustaining human life. However vegetation’s natural regulatory capacity extends beyond political boundaries, acting as a mediating force to anthropogenic activity. Vegetation’s uninstructed equilibrial capacities can be demonstrated through processes such as phytoremediation allowing for the removal and assimilation of airborne pollutants and particulate matter and evaporative cooling, reducing high anthropogenic induced atmospheric temperatures. (H. Lambers et al, 2008). For example a mature tree transpires

26

over 88 litres of water a day, equivalent to five room sized air conditioners operating for 24 hours (D. Nicholson-Lord, 2003) Biocentric ecosystems without human intervention remain in stasis; everything that is required for life to survive within that network is recycled within. In order to achieve a similar state of continuity in anthropocentric ecosystems, human built forms and systems must imitate nature’s ecological processes, structures and functions. (K, Yeang 2007).

Â

27 Â

Indoor Air Quality (IAQ) The increased pollution in urban areas and widespread use of synthetic building materials, furnishings and appliances has created negative effects on the quality of interior air. These airborne pollutants have produced adverse human health affects including: allergies, asthma, infectious diseases such as legionellosis and the common low level effects referred to as sick building syndrome (SBS). Modern synthetic products emit various harmful gases including carbon monoxide, radon and Volatile Organic Compounds (VOC’s).

IAQ is also affected by dust, microbial contaminants such as mold and bacteria and human respiratory bioeffluents (H. Levin, 2010, T.C. Wang, 1975).

There has been a large amount of research into the improvement of IAQ from bodies such as WHO, EPA and ECA, recommendations such as that of the ASHRAE suggested increasing the minimum supply of outdoor air from 0.142 in 1981 to 0.566 m3/min/person in 1989 in order to revitalise the stagnant indoor air and improve air flow (ASHRAE, 2010). This however did not mitigate the problems regarding human and environmental health. In addition according to a study by Menzies et al (1993), further increase of ventilation rates up to 1.81 m3/min/person contributed, but did not eliminate pollutant problems, therefore mitigation of IAQ through increasing ventilation rates was deemed an insufficient solution (Menzies et al 1993). In addition the increased use of HVAC systems requires large amounts of energy and can also become a source of pollution if not properly maintained (EPA 2012).

Improving Indoor Air Quality (IAQ) With Vegetation.

As the air we breathe is derived from living vegetation, the concept of using such vegetation for improving IAQ has strong foundations as a scientific solution. The interactive capacity of vegetation with relation to air pollutants has been recognised and extensively documented (eg H.W. Smith, 1976, D. Fowler, 2002, P.K. Beckett et al., 2004). Research has shown the use of vegetation provides an essential adsorption surface interacting with the surrounding atmosphere (Appendix 1.4, 1.5) (Smith, 1976).

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Studies into reducing pollutants through the use of vegetation were recorded by Joseph priestly (1772) from as early as 1772, during the discovery of the photosynthetic process and plants capacity to remove CO2 (D.L. Klass 1998).

Since 1980 several experiments have been conducted on the use of interior vegetation to remove VOC’s from airtight rooms (B.C. Wolverton, J.D. Wolverton 1984, 1985, 1989 1992, 1995). One of the key findings of this research demonstrated that each plant has a personalised genetic code, enabling it to create culture specific microbes in order to facilitate phytoremdiation, thus facillitating the assimilation of biodegrading pollutants at high levels and effectively improving IAQ (A.D. Roivira, C.B. Davey 1974, B.C. Wolverton, J.D. Wolverton 1992). The majority of Wolverton et al’s, research was carried out on vegetation cultivated in optimum conditions on a small laboratory scale, thus providing few practical options as there were no provisions for planting densities, realistic light levels and air exchange rates.

However field experiments in real office situations have shown that several common species of interior vegetation have the capacity to remove VOC’s such as benzene and hexane by 75%, to below 100ppb (M Burchett et al 2006).

Figure 4. Air filtering climibing and trailing plants

Figure 5. Desktop air filtering vegetation

Additional research into the effect of plants on IAQ, suggests that the accumulation of particulate matter on interior horizontal surfaces through

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deposition and sedimentation can be reduced by as much as 20% with the use of vegetative techniques. Experiments indicated that increased humidity and electrostatic effects were linked to plant mechanisms that caused a reduction in airborne particulate through the attraction and adherence to leaf surfaces. (V.I. Lohr & C.H. Pearson-Mims, 1996).

The interior organisation of the BGW headquarters building provides an operational example of the holistic use of vegetation in environmental control and aesthetic place making. The apparent success of this building to regulate and improve the internal building climate is a vindication of the application of independent theoretical scientific data from the previously discussed sources (Appendix 2.1).

Figure 6. BGW building, main atrium

Figure 7. BGW building, multi-level vegetation

Ventilation The internal climate of any building is subject to higher levels of CO2 than is found outdoors, however with the introduction of airtight buildings in the sustainable construction process in order to conserve energy, these levels have been regularly recorded at up to 10 times higher than outdoor levels (US EPA, 2011). The high levels are primarily due to the accumulation of C02 from occupants breathing, unflued gas powered appliances and generally high Â

30 Â

concentrations of CO2 naturally or mechanically introduced from the exterior medium (C.A. Erdmann et al., 2003 EPA, 2011). The recommended maximum indoor CO2 concentration for modern airtight buildings is 1000ppm (ASHRAE, 2011), however in recent studies into the levels and effects of CO2 in office environments, concentrations of up to 1600ppm were found (M.D. Burchett et al., 2010). The increased levels of CO2 circulating within any building, especially in modern airtight structures as the rate of natural infiltration and airflow is reduced, can cause adverse health implications such as drowsiness, loss of concentration and respiratory irritation (G.M. Apte et al., 2000). These adverse health issues have been shown to reduce occupant’s productivity and overall performance and in some cases the respiratory symptoms have become more severe (Seppänen et al., 2006). Buildings with high concentrations of CO2 also require extensive need for HVAC systems as previously discussed.

Improving Ventilation with vegetation Vegetation releases oxygen during photosynthesis (Appendix 1.1) providing a scientific basis for its use as a natural ventilator of the building interior. The capability of plants to remove CO2 from the atmosphere via photosynthesis is a result of their ability to intercept light. Therefore light plays a fundamental role in the photosynthetic rates of plants and consequently their value in buildings in terms of reducing CO2 concentrations (D.O. Hall, 1999). As light is central to the process, factors such as leaf size, height, position, orientation and the suns elevation and azimuth angles during the day are essential to produce the best photosynthetic rates and subsequent CO2 reductions (D.O. Hall, 1999, M.D. Burchett et al., 2010).

Estimations based on previous research indicate that every square meter of vegetative surface can attenuate to more than 300g of CO2 per annum when situated in habitual interior conditions (K. Freeman, 2008). In addition recent studies have shown that the presence of vegetation in buildings was associated with 10% CO2 reductions in air-conditioned buildings, and by 25% in naturally ventilated buildings. This explains vegetation’s ability to assimilate carbon from the atmosphere and secondly its increased effectiveness in naturally ventilated buildings where airflow and humidity have an effect on dispersion of gases

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through plant stomata (M Burchett et al., 2001). Higher reductions can also be achieved when vegetation is combined with other efficient mechanical technologies such as biofiltration systems. Interior vegetation has the potential to reduce energy demands and fuel costs of HVAC systems by its passive capacity to ventilate and subsequently reduce the carbon-footprint of urban structures (Summerville et al., 2008, M. Burchett, 2010).

Figure 8. Alterra Laboratory, Natural ventilation

Figure 9. Vegetated ventilation

Figure 10. Alterra Laboratory, energy and ventilation concept

Â

32 Â

Interior Noise Pollution Noise pollution is, “displeasing or excessive noise that may disrupt the activity or balance of human life” (D. Harper, 2012). With the increase of high density compact interior spaces and the integration of mixed use buildings in urban areas, interior noise pollution has become a problem affecting productivity and in some cases health amongst urban residents. Interior sources of noise pollution include building installations and appliances such as HVAC systems and also high levels of noise generated from humans. The transmission of exterior noise through the building envelope derived from extraneous sources such as traffic, construction and industry can also contribute to high levels of interior noise pollution (M. Wilson et al, 2003).

Reducing noise pollution of the indoor environment has proven to be a highly problematic issue to solve, as buildings that rely on natural ventilation systems such as window openings to maintain user comfort, are directly exposed to exterior noise pollution. This encourages the use of mechanical HVAC systems that subsequently have a negative impact on energy use and costs impacting on the overall sustainability of the building (M. Wilson et al, 2003).

Reducing Interior Noise Pollution with Vegetation

Figure 11. Trgy Insurance building, Planted lift shaft, vegetated panels installed to reduce noise

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There has been a limited body of research into the use of interior vegetation to reduce noise levels, however experimental research in exterior settings has established the capacity of plants as an effective medium and therefore provides reason for use at an interior scale (Wong et al, 2010). One principal body of relative research implemented by Costa (1995) shows that vegetation can contribute to the reduction in background noise levels inside buildings by up to 5dBa, thereby making the internal environment more comfortable for the occupant’s (Appendix 2.2) (P Costa & R.W. James, 1995). The case study provides quantative research supporting Costa’s theory of the use of vegetation as technique for the attenuation of noise within buildings, particularly noise of high frequencies deemed most irritating to the buildings users. According to Costa (1995) interior plants can reduce indoor noise pollution by techniques such as absorption, diffraction and reflection, outlined in (Appendix 1.6).

Figure 12. Noise reducing vegetated column

Figure 13. Noise reducing vegetated wall

The effectiveness of the plants varies with the frequency at which the sound is generated and the physical properties within the room. The type of plant, its size, shape, orientation, mass, foliage surface area, its container and compost all have an effect on the sound reduction capabilities of indoor vegetation.

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Generally vegetation that comprises small leaf area but a high overall foliage area is most efficient at reducing noise levels due to its dispersive properties, examples include Spathiphyllum wallisii (peace lily), Philodendron scandens (sweetheart plant), Dracaena marginata (Madagascan dragon tree) and Ficus benjamina (weeping fig) (P Costa & R.W. James, 1995). An example of the application of vegetation solely for acoustic purposes can be seen in The Green Culture Centre in Herten, Germany, which has utilised the combination of plants and glass to create perfect acoustic conditions in its concert hall and library with no additional mechanical alterations, thus providing an passive method for acoustic attenuation (Figure 14,15 & 16.) (Dieter Schempp, 1997).

Figure 14. GCC, Herten front façade

Figure 15. Building and vegetation plan

Figure 16. Vegetated wall provides perfect acoustic quality

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Interior Air temperature and Humidity Research has shown that varying interior building temperatures have been known to reduce productivity. In the winter months, low indoor temperatures have been correlated with increased levels of respiratory and cardiovascular disease particularly among the elderly (M.Wilson et al, 2003). In addition due to global warming there has been growing concern about the effects of high exterior temperatures inducing heat stress within the interior environment.

Research into the affects of high interior temperatures in a manufacturing plant, demonstrated that for every degree interior temperature levels rise above 27oC, 1% efficiency is lost per man hour In some cases exceedingly high temperatures have been related to heat exhaustion, heat stroke and eventual collapse (W. Tombling, 2006).

Relative humidity within the building envelope can also have a very influential impact on user comfort. A low internal humidity can result in an arid atmosphere, leading to irritation of the eyes and throat whereas a high internal humidity can impede the body's natural reaction of cooling down and also increase mold spores (B. Giovanni, 1998). The Chartered Institute of Building Services Engineers in their Guide Volume A - Design Data (2010) recommend that internal building humidity levels should be between 40-70% (CIBSE 2010).

Further more studies have indicated that the combination of high interior air temperatures and air with high relative humidity is stuffy and has been linked in some cases to high levels of SBS. (O.A. Seppänen, W.J. Fisk, 2004). The increased use of HVAC systems to mitigate the problems of high interior temperatures and humidity levels creates a succession of problems on a much larger scale in terms of increased energy demand and therefore increased use of fossil fuel derived energy therefore an alternative approach to sustainably improve the interior environmental conditions must be implemented.

Cooling a Building by Shading With Vegetation.

As solar energy strikes vegetation it is dispersed by foliage, absorbed by photosynthesis (appendix 1.1, 1.3) and a fraction is reflected back to the atmosphere thus creating a cooling effect beneath the vegetative canopy. The Â

36 Â

use of vegetation to reduce internal temperatures via shading techniques requires a considerable amount of planning and interdisciplinary collaboration (Dieter Schempp et al,1997). A diverse range of deciduous plants such as Quercus (Oak), Fagus (Beech) and Betula (Birch) have been selected, as their ability to control the loss of foliage in winter, allows more solar energy into the building for heating, whilst in summer increases in the growth of foliage provides a larger surface area to create shade substantial enough to have a cooling effect (V Bradshaw, 2010).

Figure 17. Ficus Benjamina providing shade

Figure 18. Large trees providing shade

Small plants such as Ficus benjamina (Fig plant) situated near windows in a dense office environment can avoid the need for blinds and other modern or mechanical shading techniques and still provide the benefits of a view. In atriums and other highly glazed spaces, large plants and trees such as those used in BGW (Appendix 2.1) can be used to replace manufactured products such as sun breakers or louvers (V Bradshaw 2010, Dieter Schempp et al, 1997).

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Figure 19 & 20. Musa Sapienta (Banana tree) providing shade

Regulating Interior Air Temperature and Humidity with Vegetation The capacity of vegetation to moderate interior temperatures and humidity levels is derived from the natural process of evapotranspiration and photosynthesis (Appendix 1.1, 1.2). Large-scale interior planting has been shown to have a measurable effect on temperature in a number of buildings around the world for example In the BGW headquarters building (Appendix 2.1), which demonstrated a 3oC reduction in interior air temperature through the use of vegetation (Dieter Schemmp et al, 1997). Vegetation can also help to keep the air in buildings fresh and at the optimum humidity level of between 40% and 70% recommended by CIBSE (CIBSE, 2010). The effectiveness of vegetation to regulate humidity levels depends on the moisture content of the air and ventilation method (V.I. Lohr, 1992).

Figure 21 & 22. Vegetation regulating temperature and humidity in a social greenhouse

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Other Health and Wellbeing benefits Interior vegetation has been proven to increase the health and wellbeing of occupants through psychological effects. The beneficial psychological effects are believed to be derived from the subconscious link between humans and nature, which operates to reduce attention fatigue and tension and creates a feeling of tranquility. Research has shown in office situations, the presence of vegetation alone has resulted in substantially reduced illness and discomfort and improvements in occupant productivity and performance (Fjeld et al., 1996,1998, 2002; Lohr and Pearson-Mims, 1996).

Figure 23. Interior vegetated landscape providing a regulated and tranquil environment

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Heat Exchange The albedo or reflection coefficient is the proportion of shortwave solar radiation reflected from Earth into space and defines the measure of potential reflectivity of the earth's surface (Figure. 24)(EPA, 2013). Figure 25. Shows the albedo for various types of planet surface. From the table we can see the average reflection coefficient for urban regions is around 0.14 or 14%. (H. Taha, 1997).

Figure 24. Earths reflective coefficient (Albedo).

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Type of Surface

Albedo

Snow cover

0.8 - 0.9

Thick sea ice

0.70

Cement, concrete

0.55

Prairies, steppes

0.14 – 0.35

Cultivated ground

0.10 – 0.25

Oceans

0.07 - 0.24

Forest (average)

0.18

Urban regions (average)

0.14

Figure 25. Albedo values for various types of planet surface

Material longevity The durability and performance of the wide use of natural and synthetic materials in building construction is influenced by their physical composition, as well as the varying climatic surroundings to which they are exposed (WBDG, 2012). The shift away from traditional construction materials such as timber and steel towards modern synthetic polymer-based materials has had an adverse effect on their overall longevity and performance. This is particularly relevant in the use of polymers employed as composites in the structural elements of buildings (M. Jones, 2002).

The degradation effects that occur within polymer-based construction materials can substantially distress the performance of buildings, thus creating unwanted pressures on factors such as energy conservation, stability and consequently cause environmental implications (V. Nabholz, 1997). For example research has shown that surface water runoff from building elements such as roofs had the highest level of organic toxicants including polycyclic aromatic hydrocarbons and heavy metals in comparison to other urban surfaces (R. Pitt et al., 2000).

Air quality The problem of air quality with relation to the external building envelope will relate to the same problems of interior air quality, however the sources from

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which pollution is emitted originate from exterior elements and will therefore be dealt with accordingly.

Primary/ Secondary Pollutant

Major Sources

Health Effects

Environmental Effects

Carbon Dioxide (CO2)

Industrial processes, burning fossil fuels Industrial processes, burning fossil fuels

Breathlessness, coughing and wheezing Respiratory and cardiovascular illness

Contributes to global warming

Vehicles, industrial processes

Respiratory and cardiovascular illness

Eutrophication, destroys aquatic ecosystems

Carbon Monoxide (CO)

Vehicles

VOC’s e.g.

Methane (CH4)

Vehicles, industrial processes

Headaches, dizziness and nausea Eye and skin irritation, nausea

Particulate Matter

Vehicles, industrial processes Formed during the reaction of VOC’s and NOX. Vehicles, burning leaded fuel

Sulphur, particularly Sulphur Dioxide (SO2) Nitrogen Oxides (NOX)

Ozone (O3)

Lead

Respiratory irritation Respiratory illness

Accumulates in bloodstream and damages nervous system

acid rain, damages buildings and ecosystems

Smog

Smog and decreased visibility Smog, reduced crop production and forest growth Destroys aquatic ecosystems

Figure 26. Air pollutants, sources and effects

Figure 26. Shows the major anthropogenic air pollutants in urban areas, their respective sources and problematic effects. From analysing the table it can be seen that the sources of pollutants primarily come from burning fuels for energy use. The increase in air contaminants in urban regions has created a number of adverse health and environmental implications. However, in relation to the quality of air of the interior environment, the ventilation process of transporting outdoor air into a building increases the overall pollution content and subsequent health and performance impacts previously discussed. Although strict measures are taken to clean ventilated air, the process requires large amounts of energy, creating air pollution sources connected with its conversion, transportation and use, subsequently creating increased outdoor exposure.

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ation changes if a particularly tall building sticks out above the su

ow over the large scale urban area (briefly described above) has no considerable

ure 12a and b,Without the regular oncoming wind impacts against the windward fac cleaning HVAC systems can also become a principal source of

cts as an obstacle to the wind that changes the air flow within a smaller scale. pollution of both exterior to interior mediums (M. Wilson et al, 2003).

ation in the center at asabout of the height fected point by the existence of building shown3/4 in Figure 10 building [6]. In Figure 10, (a) [6]. Fro Air Flow Around Buildings

and (b) illustrates the generated flow zones associated with the typical pattern of

ile much of the rest streams down the windward face to the gr The irregularities in shape, orientation, mass and size of buildings in cities acts

s express as multiples of the barrier height (h) [6].

as an obstacle to wind creating changes in airflow represents the affect of

stream from buildings the tall building, it enhances the upward wind of ad on airflows with regards to streamlines, obstruction and archetypal

ding

flow zone generation (Figure 27. a, b, c & Figure 28.) (M. Oka, 2005)

Figure 11. Flow Regimes Associated with Different Urban Geometries g vortex near the surface (Figure 12b) [6]. The remaining is defle

around the back to give the horseshoe-shape characteristic (Figur

the ground on a column, or if there is a walkway and/or open

ward stream will produce a jetting through-flow as indicated in Figu

und a Tall Building with Lower Buildings upwind Figure 27. a) Isolated roughness flow, b) Wake interference flow, c) Skimming flow

ettings, the air flow pattern depends upon the geometry of the array, especially the

W) [6]. Figure 11 illustrates a flow regimes associated with different urban 4

Figure 28. Flow around a tall building, with lower buildings upwind

The increased speed and turbulence of airflows around urban structures has a

Source: Oke (1987)

significant affect on the comfort of urban populations in any climatic region.

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5

Airflows around urban areas have the potential to; create wind speeds causing irritation to pedestrians, picking up litter and dust and dispersing it into the atmosphere, determine the potential for the heating/ventilation and consequently energy demand of buildings (S. Ahmed, A. Bharat, 2012)

Vegetation as a Mitigating Technique Vegetation as an exterior building material has been used for many centuries (Figure 29.). The use of vegetated facades is now realised to be an essential component for improving the sustainability of the built environment due its numerous ecological, economic and social benefits (N. Dunnet, N. Kingsbury 2004).

Figure 29. Hanging gardens of Babylon 1500’s

Plant processes In terms of mitigating the negative effects to external and consequently internal envelopes of buildings caused by solar radiation, the use of vegetation has the natural capacity to intercept, absorb, reflect and therefore reduce the amount of solar radiation reaching the surface below it through foliage dispersal and natural processes such as photosynthesis (Appendix 1.1, 1.3) (EPA, 2013). The potential of vegetation to construct shaded spaces therefore reduces surface temperatures and heat transmissions underneath the canopy. Vegetation also

Â

44 Â

has the potential to reduce surface temperatures through the process of evapotranspiration (Appendix 1.2)(H. Akbari, 1997).

In reference to the problem of urban air pollution vegetation has the natural ability to reduce atmospheric pollution by filtering particulates and absorbing suspended gaseous pollutants, while refreshing the surrounding air with oxygen (Appendix 1.4,1.5). The capacity of vegetation to reduce airborne pollutants and particulate matter relies on local climatic conditions and topography, type and concentration of pollutant and the species and location of the vegetation (M. Santamouris, 2001).

Vegetated Roof Systems

Figure 30. Extensive green roof, Vancouver, Convention Centre, Canada

Figure 31. Intensive green roof, ACROS building Japan

The use of vegetation on the roofs of buildings in urban areas provides a passive and effective mitigating technique. Vegetated roofs are constructed in two principal forms, extensive and intensive (Figure 30 & 31)(GRG, 2012). The Osher living roof of the California Academy of Sciences building in San Francisco (Appendix 2.3), provides a model of the effectiveness and durability of an extensive roof system as it demonstrates how the system can work on varying topographies and with minimum required maintenance. Due to extensive systems being relatively lightweight, they will require the least amount of additional structural support, improving their overall cost-effectiveness in terms of retrofitting on existing structures (GRG, 2012).

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Figure 32. Typical elemental composition of a vegetated roof

Figure 33. Interior/exterior heat exchange, traditional and green roof comparison

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Research has demonstrated cooler surface temperatures can be achieved underneath the vegetative roof surface (Appendix 2.4), reducing the externalinternal heat transmission through the building envelope reducing summer cooling loads by up to 90% (Figure 33.) (H. Akbari et al, 1997). The combination of shading and evapotranspiration reduces atmospheric air temperatures counteracting the heat sink effect of traditional structural materials. Further more the constituent elements and materials used for vegetated roofs such as soli mediums and membranes along with the vegetation itself provide additional mass and insulation, reducing heating loads when needed for example in cooler climates, thus lessening the need for mechanical heating (N. Dunnet, N. Kingsbury, 2004).

According to a recent comparative study measuring peak surface temperature reductions facilitated by vegetative shading, temperature reductions in the range of 11-25°C were recorded on the roofs of buildings in urban areas (K. Scott, 1999), in addition Sandifer and Givoni (2002) examined the thermal properties of vines on peak wall temperatures and found reductions in the region of 20oC (S. Sandifer, B. Giovani, 2002). There has also been urban sitespecific research into the benefits of vegetated roofs for example; the city of Chicago compared surface temperatures on a vegetated roof with that of an adjacent building throughout the summer season. The comparative study showed the surface temperature of the vegetated roof ranged from 33-48°C, while the exposed roof of the adjacent building was around 76°C. The air temperature above the surface of the vegetated roof was recorded to be up to 4°C cooler than the exposed roof (DOE, 2004).

The Osher living roof on the California Academy of sciences (Appendix 2.3) (Figure 34.) building provides working example of the effects of vegetated roofs reducing temperature fluctuations as research has shown an regulated interior temperature 10°F lower than that compared to traditional roof construction, in addition surface temperatures were also found to be up to 40°F cooler than that of high albedo surfaces.

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Figure 34. The Osher living roof, California Academy of Science

By simply acting as a barrier supporting the protection of the building fabric against UV radiation and reducing temperature fluctuations, vegetated roof systems have the capacity to extend the life span of building materials, therefore improve energy conservation and reducing the risk of structural failure For example recent research has demonstrated that vegetated roof coverage can stabalise surface temperatures extending the whole lifecycle of materials such as waterproofing membranes by more than 20 years. A selection of vegetated roofs used for experimentation in Berlin has lasted up to 90 years without requiring the need for any major repairs (S. Mohammed et al., 2012).

As outlined in Appendix 1.1,1.4 & 1.5, natural vegetative processes remove urban pollutants (Figure 26.) from the air. The reduced energy consumption of a building as a consequence of utilising vegetation as discussed above further reduces air pollution and greenhouse gas emissions associated with energy production. In addition the application of vegetated roof systems impedes the formation of ground level ozone through reducing atmospheric temperatures, as ozone forms more readily with increased air temperatures. Vegetated green roof systems also sequester carbon based pollutants from the atmosphere, however as the growing medium in extensive roof systems is relatively thin, vegetated roofs do not have as much impact in this respect as other forms such as urban forests (S. Sheweka & N. Magdy, 2011).

There has been a large amount of research into the air purifying effectiveness of green roofs to attempt to support their use in urban areas, research Â

48 Â

approximates that on an annual basis, a 93m2 vegetated roof can absorb up to 40lbs of particulate matter whilst simultaneously reoxgenating the surrounding atmosphere (S. Peck, M. Kuhn, 2003). The quantity of air pollution depletion by vegetated roofs in Chicago was measured using a dry deposition model. With the application of 19.8 ha of vegetated roof, the removal of 1675 kg of air pollutants comprising 52% ozone, 27% nitrogen dioxides, 14% particulate matter and 7% sulphur dioxides was recorded over a year making the annual removal of pollutants per hectare as much as 85kg. The researches also estimated that if every rooftop in Chicago area were to be retrofitted with vegetated roof systems, around 20,500Kg of pollutants could potentially be removed every year (DOE, 2007).

Figure 35 & 36. Extensive green roof, 900 North, Michigan Avenue, Chicago

In terms of the problem created by high wind speeds around buildings and structures, the use vegetated roofs can provide a technique to reduce and disperse airflows particularly when caused by buildings emerging through the urban canopy. As wind blows across the vegetated surface and encounters obstructions such as large shrubs of an extensive vegetated roof, a fraction of the airflows momentum is absorbed, reducing its speed and dispersing its flow (Appendix 1.7)(S. Mohammed et al., 2012).

Â

49 Â

Vegetated Walls

Figure 37. Living wall, Madrid, Spain

As vertical façades provide nothing more than aesthetical and structural elements to a buildings envelope and surrounding space, they can therefore create an ideal surface for integration of vegetation and optimize the natural plant processes (Appendix 1)(Dunnet & Kingsbury, 2004).

Vegetated facades or walls mitigate the issues surrounding urban areas discussed above in the same way as vegetated roof systems, through shading, evapotranspiration, dry deposition and phytoremediation outlined in (Appendix 1.2, 1.4, 1.5). Vegetation can be applied to a façade via two principal methods; either rooted into the ground or rooted into artificial substrates or pots suspended on the façade itself. Within the two construction methods discussed, a vegetated wall can have the potential to directly green the façade, by using the vertices as a guide in which to grow up, or indirectly when the façade and vegetated surface are separated with the application of an air cavity. The structural differences and variations of each type of vegetated wall are shown in Figure 38 (M. Ottele, 2011). The more elaborate vertical systems that are

50

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Figure 41. Extensive living wall, Vancouver, Canada

Vegetated walls create a microclimate through the natural plant processes of shading and evapotranspiration in a similar way to vegetated roof systems (Appendix 1.2), resulting in a more regulated, amiable urban environment (S. Sheweka & N. Magdy, 2011) Figure 42 & 43. Shows the thermal effects of

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applying vegetation to a building façade, demonstrating substantial temperature " deviations between exposed and vegetated surfaces (Wong et al., 2009). %&" '(%)'*'" %'*+'),%-)'" " ./-0%-,%1&23" 45&%" 6-)127" %5'" 6,8" ,26"0&&/",%"2175%9:";1%5"0&23%,2%" '(+&3-)'" %&" 3-2/175%" ,26" ;126<" =5'" 0/1*,%'" ,%" %5'" .,>,6'" 13" 0&*+,),?/'" ;1%5" ,)16" &)" ,/+12'" 0/1*,%'" ,26" &2/8" 3-1%,?/'" %&" 3+'01.10"%8+'3"&."+/,2%3<"" "

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GHHI<" 'D,+&),%1&2:" " Figure 42 & 43. Vegetated façade and thermal image showing temperature @17-)'"#<AJ"E5&%&7),+5"%,K'2"&."%5'" ;,%')" 12%&" %5'" ,1)<"difference =5'" )'3-/%" &." %513" 13" ," *&)'" +/',3,2%" 0 3,*'".,>,6'";1%5",2"12.),)'6"0,*')," ,)',<" C'%;''2" .,>,6'" ,26" %5'" 6'23'" D')%10,/" 7)''2" /,8')" 4@LMN9";1%5",*?1'2%",1)"%'*+'),%-)'"GA" %5'"3-?3&1/",3")&&%'6"12",)%1.101,/"3&1/"?,3'6"383%'*39","3%,7 OP<" The barrier formed by vegetation impedes direct solar gains to the façade, thus " R%,72,2%",1)"5,3",2"123-/,%127"'..'0%S"7)''2".,>,6'3"0,2"%5 T'(%)," 123-/,%1&2T" &." %5'",26" ?-1/6127" .,>,6'" 4U12K'" '%" ,/<:" AI Q,)6"exterior 3-).,0'3" &." temperature 0&20)'%'" ensuring a cooler experienced interior and air the 13" ?/&0K'6" ?8" % AI$G9<" W/3&" 61)'0%" 3-2/175%" &2"inside %5'" .,>,6'" 7/,33" '20&-),7'" )-2&.." &." ?/&0K127"&."%5'"3-2/175%"'23-)'3"%5,%"%5'"%'*+'),%-)'";1//"? ),12;,%')" 12%&" %5'" 3';,7'" is reversed, building (S. Sheweka, N. Magdy, 2011).

During winter this process 5&-3'<"M2";12%'):"%5'"383%'*";&)K3"%5'"&%5')";,8")&-26",2 383%'*<" E/,2%3" ?-..')" ;,%')" &2" %5'1)" /',." 3-).,0'3" /&27')" %5,2"

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as a pocket of stagnant air is trapped between the vegetated and exposed surfaces creating insulating layer, Research into the air pocket between the vegetative layer and the building façade shows that with foliage consisting of leaf sizes of around 5cm produces a thermal conductivity value of 2.9 W/m2K, a similar value found over double glazed facades (C. Brebbia, 2012, M. Kohler, 2008). Recent studies have compared differences in the temperature gradient across exposed walls and vegetated walls, their results demonstrated 10°C difference with the use of a vegetated wall. Vegetated walls therefore provide a medium in which to heat, cool and reduce overall radiative heat exchanges of a building without the additional of energy use fuel, providing a completely passive facility (Appendix 2.4). (Dunnet and Kingsbury, 2004, C. Brebbia, 2012, M. Kohler, 2008, M. Ottele, 2011).

A model example of the temperate effects of vertical vegetated systems can be demonstrated by Ken Yeang’s Solaris building in Singapore (Appendix 2.5).

The use of vertical and horizontal vegetated systems in this case significantly contributed to the overall energy efficiency of building in terms of heating and cooling loads, producing a 36% reduction in overall energy consumption. The Solaris building and the theory behind Yeang’s concept of ecomimicry provide a foundation on which to base future structures in order to create more ecologically functional structures (k. Yeang, 2007).

The capacity of a vegetative façade to attenuate high concentrations of air pollution mimics that of a vegetated roof system, however the location of the applied surface is generally within the urban street canyon significantly closer to the varying sources such as nitrogen oxides, carbon monoxide and particulate matter released from motor vehicles making it a more effective medium (R. Avissar, 1996). For example field experiments on the effect of vegetated façades attenuating to high sulphur dioxide concentrations demonstrates a clear link between pollutant reductions and vegetated surfaces compared to that of the exposed surface figure (Bussotti et al., 1995).

54

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Urban heat islands Low albedo surfaces combined with the emission of heat, moisture, and pollutants derived from anthropogenic activity, creates a modification of the emission properties of the earth’s atmosphere and surface, consequently causing an increase in atmospheric temperatures by several degrees in comparison to the temperatures of the surrounding rural areas (Figure 45.)

(EPA, 2013, H. Taha,1997). This concentrated temperature increase is known as the urban heat island effect (UHI) (Landsberg 1981, M. Sanatamouris, 2001). The results from the Buenos Aires UHI study (Appendix 2.6) provide quantitative data, showing that areas of building density and population concentration provoke temperature increases of over 3°C demonstrating the direct correlation between the effects of urban morphology on thermal environmental impact.

Figure 45. The Urban Heat Island, sources, process and effects at meso and micro scales

The intensity of the UHI is characterised by climatic, seasonal and topographical conditions of specific urban regions. In general, late afternoon

56

urban temperatures correlate with the highest intensity’s of UHI’s (H.E. Landsberg, 1981).

The increased temperatures in cities caused by UHI’s, particularly in summer creates a significant increase in energy demand for the air conditioning of buildings. For example, in Los Angeles the requirement for electricity increases around 2% for every 1F in temperature increase. This demand for energy results in 1-1.5 gigawatts of power being used to compensate for the UHI, economically this amounts to a substantial increase in energy costs, in the region of $100,000/hour (H.Akbari, HIG 2005). The increase in energy consumption creates further problems, as the electricity is predominantly derived from consuming fossil fuels (H.Akbari, HIG 2005, M. Santamouris 2001, H.E. Lansberg). The elevated temperatures and subsequent increase in environmentally degrading pollutants impacts on air quality and the health and comfort of urban residents contributing to heat discomfort, respiratory difficulties, exhaustion and heat-related mortality (EPA, 2013). Research from 1979-2003 showed intense heat exposure in urban areas resulted in the contribution to more than 8,000 premature deaths in the U.S.A exceeding figures above other natural disasters such as earthquakes. The UHI effect has also been found to impair the water quality of natural aquatic systems (C.P. Lo, D.A. Quattrochi, 2003).

Air quality The accumulation of the various localised sources of air pollution (Figure 26), contribute to negative and ecological impacts experienced in urban areas. The large amounts of CO2, VOC’s such as methane and assimilation of ozone are considered primary greenhouse gases, having a fundamental contribution to global warming. The emission of sulphur dioxide in industrial processes acts as a precursor in the chemical creation of acid rain (Figure 46.), having the capacity to damage buildings both structurally and aesthetically through erosion and chemical weathering and also disrupt the natural balance of aquatic and woodland ecosystems. The accumulation of particulate matter, VOC’s and ozone also creates large amounts of photochemical smog, causing health and visibility issues (Figure 47.) (EPA, 2013).

57

Figure 46. Acid rain process and effects

Research has shown that urban air pollution has caused more than 3.3 million deaths worldwide, contributing to a multitude of health conditions such as aggravated breathing and coughing, respiratory infections, heart disease, and lung cancer (WHO 2011). A recent study in the Los Angeles has shown over 3800 people die prematurely every year because of highly concentrated air pollution levels. The low level conditions such as restricted breathing, coughing and wheezing have exacerbated hospital emissions, and medicine distribution creating adverse economic affects (Wikipedia, 2013).

Figure 47. Urban smog, Los Angeles

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Airflow in Urban Environments In general the resistance resulting from the rough urban canopy reduces the wind speed creating a transitional zone known as the urban boundary layer, which sits between the earths surface and the undisturbed airflow above the urban canopy. The speed of the airflow close to the earth’s surface is steeply reduced creating areas of turbulence due to the friction generated by buildings (Figure 48.) (M. Santamouris, 2001).

The reduced airflows within urban areas have a significant affect on the comfort of urban populations in any climatic region. They have the capacity to reduce the amount of air pollution dispersal contributing to already high concentrations, increase the urban heat island effect, determine the potential for the heating/ventilation and consequently energy demand of buildings (M. Santamouris, S. Ahmed & A. Bharat, 2012).

Figure 48. Urban air flows. a) Boundary Layer, b) Rural layer, showing mixed surface roughness

59

Noise Pollution The increase in high-density schemes together with mechanisation means that humans suffer from the negative impacts that noise pollution has on the quality of health and the urban environment (A. Ritchie, 2009). According to the European Community’s Green paper (2004), It has been estimated that around 20% or 80 million people within the European Union suffer from unacceptable noise levels generally above 65 dB in regions known as "black areas" (EUP, 2004). These high levels are created primarily by anthropogenic sources (Figure 49.) (N. Berglind et al, 2004).

Figure 49. Pressure and Decibel levels of anthropogenic noise pollution

Urban Runoff Urban runoff refers to the increase in surface water runoff created by buildings and infrastructure constructed from impervious surfaces such as asphalt and concrete (Figure 50.). As urban runoff water flows over non-porous surfaces it absorbs pollutants primarily caused by anthropogenic activity, the principal contaminants of urban runoff water are shown in (Figure 51.) (A. Nagasea & N. Dunnettb, 2012)

60

Figure 50. Comparison of infiltration percentage of natural and impervious ground cover

Categories of Principal Contaminants in Stormwater Category

Examples

Metals

Zinc, cadmium, copper, lead

Organic chemicals

Pesticides, oil, gasoline, grease

Pathogens

Viruses, bacteria, protozoa

Nutrients

Nitrogen, phosphorus

Biochemical oxygen demand (BOD)

Hydrocarbons, human/animal waste

Sediment

Sand, soil, and silt

Salts

Sodium chloride, calcium chloride

Figure 51. Principal contaminants of urban runoff

The environmental degradation caused by urban runoff pollution has a number of severe affects both on ecological systems and human health. Water that flows over urban surfaces accumulates heat; in some cases temperatures can rise to as high as 90°F, as it flows towards natural streams or lakes. This warm water along with pollutants has been found to disrupt the balance within aquatic ecosystems. The pollutants carried in this water also have an affect on aquatic systems due to alterations of the water chemistry. Some metals such as lead and synthetic organics are toxic to aquatic life causing loss of habitat (NRDC 2012, A. Nagasea & N. Dunnettb, 2012).

In terms of human health, urban runoff has been found to transport diseasecausing bacteria and viruses causing serious concern for water supply and

61

recreational activities. Research has shown that over 90% of the population in the U.S. rely on public supplies of drinking water, 19% of that population are served by systems with reported health violations (NRDC, 2012)

Vegetation as a Mitigating Technique In the previous chapters techniques and approaches to mitigating the environmental effects of urbanisation through the use of vegetation were discussed on a localised scale. Although these techniques are beneficial, for vegetation to be truly effective as a primary technology in improving urban sustainability its use must be considered within the context of larger initiatives.

Large Scale use of Vegetated Roof and Wall Systems As the albedo of surfaces in urban areas along with overall urban topography are two of the primary contributors to the UHI effect, the wide scale use of these systems throughout an urban area has the potential to significantly reduce urban temperature fluctuations, for example an experiment carried out by W. Pompeii (2010) estimated that with there extensive use, vegetated facades could reduce the UHI effect by up to 2oC (W. Pompeii 2010).

The potential effectiveness of the use of vegetated facades at an urban scale has been recognised across the world. For example 35% of all cities in Germany now have provisions for the integration of vegetated roofs in their building regulations (D. Rømø, 2011). The city of Stuttgart provides a functional example of implementing the use of vegetated roof systems across an urban area. Stuttgart is a highly urbanised area comprising large-scale industry and irregular topographical conditions making it particularly susceptible to a range of environmental problems. Vegetation was recognised as a sustainable technology to mitigate this, however due to the cities compactness the application of large vegetated parks was not deemed an option. Since 1986 Stuttgart has utilised this financial support and has set regulations for all new developments comprising roofs below a 12o pitch to be applied with vegetation.

With over 2,000,000m2 of vegetated roof cover, Stuttgart is considered one of the leading vegetated roof cities in the world, the problems of UHI and air

62

quality have been significantly reduced, and new areas of biodiversity have been established throughout the city (A. Kazmierczak, & J. Carter, 2010).

Figure 52 & 53. Extensive use of vegetated roofs, Stuttgart, Germany

In terms of mitigating the effects caused by the degradation of urban air quality the vegetative processes (Appendix 1) and the applications of vegetated facades discussed in the previous chapter provide a foundation to extrapolate their use on a larger scale. A comparative study in the midtown area of Toronto Canada, into the use of various vegetated roof situations and air pollutant reductions with reference to the reductions already imposed by the existing urban vegetation was carried out. The experiment demonstrated that in one situation where vegetated roof surfaces signified 20% of total roof area, 10-20% of the pollution removed by the existing vegetation was also removed by vegetated roof systems. The results thus estimated that if vegetated roof systems were retrofitted to all applicable surfaces in the Toronto midtown area, an increase in overall pollutant reduction of around 25-45% would occur (B. Bass, B. Baskaran, 2003).

Vegetation has the capacity to absorb, reflect and diffract sound, thus reducing noise pollution (Appendix 1.6). The efficiency to do so in an urban environment appears to be dependent on plant type, density, location and sound frequency.

The materials used in vegetated facades including substrates and soil mediums were found to have a substantial absorbing effect (M. Ottele, 2011). Further more research has shown that an increase in vegetation coverage directly increases the sound absorption coefficient (Wong et al. 2010). There has been little research into the large-scale application of vegetated facades attenuating to urban noise pollution, however large bodies of research on smaller scales

63

such as that of Wong et al. (2010) has proven its potential for use at an urban scale (Wong et al., 2010).

With reference to the negative environmental impacts created by urban run off, vegetated facades and roofs are considered as one of the most important mitigating techniques given the lack of available land in urban areas and their ability to prevent excessive urban runoff from the source  (A. Nagasea & N. Dunnettb, 2012). Their effectiveness is reliant on specific plant species, density and layout and their feasibility within urban areas varies between different climatic regions (M. Scholz, 2004). In cases of significant urban runoff, for example in short storms, vegetated roofs have the capacity to store excess water in the soil and vegetation, reducing and delaying overall peak runoff (J. Lundholm et al., 2010).

The need for sustainable management of urban runoff has created an extensive body of experimental research and many studies have provided evidence that vegetated facades can significantly reduce the amount of surface water runoff when used throughout urban areas (A. Nagasea & N. Dunnettb, 2012, M. Scholz, 2004). A summary of studies in Germany from 1987-2003 showed that capacity of vegetated roofs to retain water ranged from 45-75%, the study also demonstrated that with large scale use across urban areas, vegetated facades have the potential to contribute to a fully vegetated sustainable urban drainage system (J. Mentens, D. Raes, M. Hermy, 2006).

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Urban Forestry

Figure 54. Urban forest, Portland, Oregon

An urban forest refers to a collection of vegetation that is growing within an urban area, including various sorts of woody vegetation growing in and around human settlements or as a relic of a once previous thriving ecosystem. Urban forests provide an important function in the ecology of human habitats. Natural plant process (Appenidx 1) depict how single elements of vegetation can modify its surrounding microclimate, thus with expansion of these ecological benefits over an urban area, environmentally degrading issues such as UHI’s, urban air and noise pollution can be effectively reduced and controlled (D. Armsona, P. Stringerb, A.R. Ennosa, 2012) In many countries there is now an understanding and appreciation of the importance of integrating natural ecology within urban areas. For example the city of Toronto, Canada comprises an area of approximately 20% forest cover amounting to over 10 million trees (Figure 55.). Toronto’s vast urban forest system is of the highest environmental importance to the area, providing the equivalent of over $60 million in ecological services annually exceeding the cost needed for forest management. Research has shown that Toronto’s vegetated

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areas collectively store over 1.1million tonnes of carbon annually which has been compared to that emitted by around 733,000 motor vehicles. References were made in previous chapters as to the capacity of vegetation to affect energy consumption in buildings, Toronto’s urban forest has been estimated to facilitate an energy reduction in residential buildings of around 41,200 MWH a year equivalent to $9.7 million/year in electricity costs. In addition Toronto’s urban forest has been found to remove 1430ton of air pollutants a year and reduce the overall urban runoff rate by 23.8% (R. Ubens, 2010).

Figure 55. Extensive urban forest, Toronto Canada

The use of vegetation combined with sustainable urban drainage strategies creates a more flexible, effective and less costly method to mitigating the impacts of urban runoff than traditional approaches (M. Benedict 2002). Using vegetation as green infrastructure in urban areas inserts a greater emphasis on the benefits of the natural hydrological processes of infiltration and evapotranspiration to filter out pollutants, minimise the overall amount of runoff generated and reuse runoff in a sustainable manner (M.A. Benedict & E.T. Mcmahon, 2002).

Urban forests and parks, wetlands, bio-corridors, bioswales and vegetated channels (Figure 56,57 & 58) contribute to the mitigation environmentally degrading effects of urban runoff primarily by decreasing the overall amount of water and pollutants that reaches our local waters (M. Santamouris, 2001). In addition, tree roots and biomass from degraded vegetation produces soil conditions that encourage the infiltration of rainwater into the ground

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replenishing groundwater supply and reducing the risk of flooding and erosion.

Vegetation has the ability filter and absorb waterborne pollutants through root systems and transform them into less harmful substances by phytoremediation (Appendix 1.5). In general, urban forestry and vegetated channels are most effective at reducing urban runoff from smaller, more frequent storms and are used as method of control rather than a prevention technique (SCI, 2012).

Figure 56 & 57. Urban Bioswales

Figure 58. Constructed urban wetlands, Beijing, China

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The extensive use of vegetation provides solution to control air flows in urban areas. Vegetation has the capacity to influence the pattern of airflow through guidance, filtration, obstruction and deflection (Appendix 1.7) (Boutet, 1988).

The ability and effectiveness of vegetation to control airflow in urban areas is largely dependent on species, height, mass, permeability and situation (A. Ritchie, 2009). The somewhat instant transition from soft rural to rough urban topography makes it difficult to prevent the effects that dense urban areas have on air flow completely however in order to optimize the benefits of using vegetation, the design of an area around a building or open space can control pressure differences at specific points, thus affecting the pattern and speed of the airflow (M.Santamouris, 2001).

Research has shown that vegetation situated correctly can increase wind speeds where needed by up to 20% contributing to the dispersion of urban air pollutants and also mitigating the intensity of urban heat islands. When situated at the foot of tall buildings vegetation can provide a dispersive barrier reducing turbulence and high speeds, thus reducing exposure to pedestrians (M.Santamouris, 2001, EPA, 2013).

The ability of vegetation to control airflow and speed provides an essential sustainable technique to reduce building-energy consumption in two principal ways. The reduction of air infiltration into buildings and convective heat loss from exterior surfaces air infiltration (Y. Liu & D.J. Harris, 2008).

The case study in Appendix 1.7 provides quantitative evidence that demonstrates how a vegetated shelterbelt can substantially reduce the effects of air infiltration and low convective heat loss. The overall results show a significant energy-saving of 18.1% of the total heating-load, the highest recorded reduction being 631KWh in February, a 17.6% decrease in heat loss through air infiltration and 7.8% decrease in the convective heat-loss through building façade (Y. Liu, D.J. Harris, 2008). The overall energy reductions have advantageous effects in terms of the urban environment such as reducing temperatures and the over use of fossil fuel derived energy.

Â

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Biodiversity An essential benefit, which must be considered, is vegetation’s natural capacity to rejuvenate biodiversity in urban regions. There are currently very few cases of the use of vegetation on building facades where habitat creation is the primary objective, with the exception of a few projects such as the grass roofs, London However habitats that have been created naturally can also be recreated and applied to the building façade including ecosystems such as grassland, woodland, scrub and heath. In theory any habitat can be created in any location on any medium throughout an urban area. The use of vegetation producing a medium for habitation as a byproduct when tackling the more serious environmental problems in urban areas, passively increases the entry and colonisation of natural organisms and can be seen to be reducing the urban to rural boundary (G. Grant, 2006, A. Ritchie, 2009).

Perception The affect that vegetation has on human’s perception is known as biophilia and indicates that generally people feel enriched when in the presence of living organisms and their vital attributes. Research has demonstrated this perceptual link between humans and nature, for example research has shown that visiting a botanical garden had a substantial affect at reducing high blood pressure and heart rates in humans (W. Brascamp, 2005). The perceived affects of well being caused by vegetation can serve to improve social dimensions of sustainability, this perhaps further supports the need for the large integration of vegetation within urban areas (K. Yeang, 2007)

A Holistic approach The application and natural benefits of vegetation have been thoroughly discussed across specific and extensive mediums within the context of improving the sustainability of the various elements that make up urban areas.

In order for the use of vegetation to be recognised as a primary construction material in sustainable urban design a more holistic approach to its use,

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exploring possibilities in ecological, economic and social dimensions and thus developing a model of amicable co-existence between the human built and natural environments must be implemented (K. Yeang, 2007) As the natural capacities and applications of vegetation are now globally recognised, large urban expanses are beginning to apply this approach. For example the concept of the city in a garden scheme has transformed the rapidly urbanising city of Singapore into a vegetated metropolis. The various green policies, projects, infrastructure and buildings briefly discussed in (Appendix 2.8) have allowed for Singapore to symbiotically urbanise within the boundaries natures systems.

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70 Â

Conclusion In order to justify the use of vegetation as a primary technology in improving urban environmental sustainability, the objective of the dissertation is to place this concept in the context of the history and future of urban expansion and the debate, synchronizing the meaning of sustainability. The aim is to investigate the use of vegetation in the internal building environment, its envelope and large-scale urban morphology to determine whether the integration of vegetation as primary technology is a viable option.

Analysis of the research has demonstrated that the process of urbanisation is arguably one of the most complex and important socio-economic phenomenons of the 20th and 21st centuries. It represents extensive changes in the interaction of anthropocentric and biocentric systems, the alteration of the earths topographical condition and disturbance of natural ecological cycles. It is a process that, from its origins has separated the mutual and historic congruence between humans and nature.

The analysis of the evidence indicates that the integration of vegetation across specific and generic urban mediums has had a positive effect and a substantive contribution in terms of creating a more sustainable urban environment.

Primarily this has been demonstrated through vegetation’s capacity to regulate and mitigate the environmentally degrading effects caused by anthropogenic activity through natural passive processes such a photosynthesis, evapotranspiration and phytoremediation, verifying its use as a cost effective, energy efficient and abundant resource and therefore justifying its application as a primary technology.

With respect to the interior landscape, the analysis has shown that vegetation can no longer be considered primarily as an aesthetic element, but more so a prerequisite in creating a correspondence between regulated interior climatic conditions and the health and comfort of its constituent users. This has been attained through vegetation’s natural ability to passively improve indoor air quality and ventilation, regulate internal temperature and humidity levels and attenuate noise pollution. This provides an interior condition, which enhances

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both the physiological and psychological wellbeing of its occupants whilst providing a sustainable alternative or support to HVAC systems, consequently preserving energy and reducing costs without impairing local and global ecological systems.

The use of vegetation on the exterior façade of buildings, demonstrates the advantages of an integrated approach. This connection expresses the use of vegetation no longer as an element of horticultural or artistic illustration, but as a primary element of the structural and functional performance of the building.

This has been attained through the ability of vegetated facades to; reduce exterior surface and interior temperatures and radiative exchanges and improve material longevity, recuperate the quality of air across both exterior and interior mediums and reduce the speed and turbulence of localised airflows. Therefore it has facilitated the advantages of interior conditions previously discussed, increasing the quality of the exterior environment, reducing the need for anthropogenic energy and manufactured materials whilst contributing to the generation of new ecological systems.

The analysis of vegetation in the generic urban form emphasises its elastic capacity through having a much more substantial effect on; reducing the effect of urban heat islands, increasing the quality of urban air and attenuating the speed and turbulence of airflows. In addition the use of exterior vegetated mediums over an urban area supports the reduction in urban noise pollution and surface runoff and increases biodiversity. Thus the large-scale integration of vegetation and its multitude of environmental advantages provide an entirely new concept to what urban is, expressing it not only as an area of economical, technological and social advancement but also as a network of anthropocentric and biocentric ecosystems to sustain life.

The use of vegetation as a primary technology provides a catalyst for changes in the future design and construction of buildings and generic urban form. In the interior envelope, to accommodate and maximise the potential of vegetation throughout their constituent spaces, the layout of commercial and office buildings has the potential to become more flexible, with green zones networked throughout the building, acting as machines to create positive Â

72 Â

environmental conditions to optimise human performance. This concept has the opportunity to be transferred throughout the building scale from large corporate offices to a domestic scale, where it is plausible to have plants specifically engineered for this condition. This may well influence the layout of the domestic dwelling to become more flexible and open plan in the future.

Utilising vegetation on the exterior envelope will reduce building costs in the long term, by reducing the need for heavy façade construction. The success of the building will not be judged by the intricacies of superfluous detail but by the performance of the external vegetative envelope. These envelopes, along with vegetated roofs will stimulate new ecologies to inhabit them, thereby creating new relationships between anthropocentric and biocentric systems.

At the generic urban form, the value of the vegetation not only as a primary technology could act as a precondition for future urban growth. As the use of vegetation provides a cost effective and fully sustainable resource, its opportunities for future application can be expanded at a global scale. For example the extensive use of green roofs in Stuttgart can provide a precedent for rapidly urbanising countries such as India and China to imitate, in order to develop their infrastructure in the most sustainable way. At this scale the opportunity for planning regulation to incorporate the use of vegetative technologies should become a prerequisite of all urban areas.

Recommendations Given these conclusions a number of recommendations can be formed as follows: •

Integrating vegetation as a functional capacity of buildings should require an understanding of local climatic conditions, not just as a method of synchronization in terms of vegetation selection and layout, but as to optimize the local ambient energy in order to reduce the need for energy consumption of mechanical systems.

•

Regulation and minimum environmental performance indicators should be introduced for the health of buildings, neighborhoods and urban areas.

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â&#x20AC;˘

Research should be prioritised, integrated and internationally funded to develop the optimum performance of vegetation and its ability to create optimum environmental conditions from building to city scale.

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Bibliography A. Allen (2009) Sustainable Cities or Sustainable Urbanisation [Online] UCL Sustainable Cities. Available from < http://www.ucl.ac.uk/sustainablecities/results/gcsc-reports/allen.pdf> [Accessed 18th December 2012] Adams J.M. (1997). Global land environments since the last interglacial.

Oak Ridge National Laboratory. [Online] Available from <http://www.esd.ornl.gov/ern/qen/nerc.html> [Accessed 23th October 2012] A. Dapolito Dunn & N. Stoner (2007) Green Light for Green Infrastructure.

[Online] The Environmental Forum Washington D.C. Available from< http://digitalcommons.pace.edu/cgi/viewcontent.cgi?article=1493&context =lawfaculty> [Accessed 9th April 2013].

A.D. Roivira & C.B. Davey (1974) Biology of the rhizosphere. In The Plant Root and Its Environment. University Press Virginia. pp 153-204.

A. Dunarintu (2012) The Socio-Economic Impact of Urbanisation. International Journal of Academic Research in Accounting, Finance and Management Sciences [Online] 2012 2, pp. 47-52 Available from <http://www.hrmars.com/admin/pics/1006.pdf > [Accessed 19th December 2012] A. Goudie. (2005). The Human Impact on the Natural Environment. Sixth edition. Oxford, Blackwell Publishing.

A. Kazmierczak, & J. Carter (2010) Adaptation to climate change using green and blue infrastructure [Online] Manchester Metropolitan University.

Available from< http://www.grabseu.org/membersArea/files/stuttgart.pdf>[Accessed 15th March 2013].

A. Nagasea & N. Dunnettb (2012) Amount of water runoff from different vegetation types on extensive green roofs: Effects of plant species, diversity and plant structure. Landscape and Urban Planning [Online] 104 (3) 15 March 2012, pp. 356–363. Available from< http://www.sciencedirect.com.ezproxy.leedsmet.ac.uk/science/article/pii/S01692 04611003239> [Accessed 14th March 2013].

A. Ritchie (2009) Sustainable Urban Design: An Environmental Approach.

Second editon. Taylor and Francis.

ASHRAE (2010) Ventilation for Acceptible Indoor Air quality. Ashrae Standard [Online] 2010, 61. Available from <http://www.grntch.com/images/ASHRAE_Standard62-01_04_.pdf> [Accessed 26th January 2013] ASHRAE (2010) Ventilation for Acceptible Indoor Air quality. Ashrae Standard [Online] 2001, 62 (1. Available from <http://www.grntch.com/images/ASHRAE_Standard62-01_04_.pdf> [Accessed 26th January 2013]

75

Bass, B. and B. Baskaran. 2003. Evaluating Rooftop and Vertical Gardens as an Adaptation Strategy for Urban Areas. National Research Council Canada, Report No. NRCC-46737, Toronto, Canada.

B.C. Wolverton & J.D. Wolverton (1984,1985,1989, 1992, 1995) Interior Plants: Their Influence on Aiborne microbes inside Energy-efficient Buildings. Journal of the Mississippi Academy of Sciences. [Online] 41 (2) 1996 pp. 80-105.

Available from < http://www.wolvertonenvironmental.com/MsAcad-96.pdf > [Accessed 26th January 2013] B. de Rudder, F .Linke (1940) Biology of the City (Biologie der Grosstadt.)

Dresden, Leipzig.

B. Giovani (1998) Climate Considerations in Building and Urban Design.

First Edition. USA, Internation Thompson Publishing B. Lomborg (2001) The Skeptical Environmentalist. Reprint edition. London Cambridge University press.

Boundless (2011) The Earliest Cities. [Online] Understanding Urbanisation and Population. Available from <https://www.boundless.com/sociology/understanding-population-andurbanization/urbanization-and-development-cities/earliest-cities/ < [Accessed 18th December 2012] C.A. Erdmann et al (2003) Mucous membrane and lower respiratory building related symptoms in relation to indoor carbon dioxide concentrations in the 100building BASE dataset. Indoor Air. Summer 2004;14 (8): pp.127–134.

C. Paik (2010) Historical Underpinnings of Institutions: Evidence from the Neolithic Revolution [Online] Stanford Graduate School of Business. Available from <www. cpaikstanford.edu> [Accessed 8th April 2013].

C. Brebbia (2012) Eco-Architecture IV: Harmonisation Between Architecture and Nature. London, WIT press.

CIBSE (2010) Design Data. [Online] The Chartered Institute of Building Serivices. Available from< http://www.cibse.org/> [Accessed 8th April 2013].

C.P. Lo, D.A. Quattrochi (2003) Land-Use and Land-Cover Change, Urban Heat Island Phenomenon and Health Implications: A Remote Sensing Approach Photogrammetric Engineering & Remote Sensing. [Online] 69 (9), September 2003, pp. 1053–1063. Available from < http://www.asprs.org/a/publications/pers/2003journal/september/2003_sep_105 3-1063.pdf> [Accessed 27th February 2013].

76

D.A. Bainbridge (2005) The Rise of Agriculture. Ambio. [Online] 14(3), 1985.

Available from< http://www.jstor.org/discover/10.2307/4313131?uid=3738032&uid=2&uid=4&sid =21101949569813> [Accessed 8th April 2013].

D. Armsona, P. Stringerb, A.R. Ennosa, (2012) The effect of tree shade and grass on surface and globe temperatures in an urban area. Urban Forestry & Urban Greening. [Online] 11 (3), 2012, pp. 245–255. Available from< http://www.sciencedirect.com.ezproxy.leedsmet.ac.uk/science/article/pii/S16188 66712000611>[Accessed 27th March 2013].

DESA (2008), The Global E-Government Survey, United Nations.

[Online] Available at: http://unpan1.un.org/intradoc/groups/public/documents/un/unpan028607.pdf [Accessed 20th October 2012] D.Fowler (2002) Pollutant deposition and uptake by vegetation. Air Pollution and Plant Life, Second Edition, p.43.

DFID (2002) Sustainable Urbanisation: Achieving Agenda 21. [Online] UNHABITAT and the UK Government Department for International Development (DFID). Available from< http://www.ucl.ac.uk/dpuprojects/drivers_urb_change/official_docs/Sustainable%20UrbanisationAgenda%2021.pdf>[ Accessed 8th April 2013].

D. Harper (2012) Noise Pollution. [Online] Etymology Dictionary. Available from< http://dictionary.reference.com/browse/noise> [Accessed 30th January 2013] Dieter Schempp et al (1997) LOG ID BGW, Dresden (Opus 30). Axel Menges Edition. Stuttgart/London. Edition Axel Menges.

D.L. Klass (1998) Biomass for Renewable Energy, Fuels, and Chemicals.

First edition. Academic press.

D. Nicholson-Lord (2003) Green Cities and Why We Need Them. London, New Economics Foundation DOE (2004) Federal Technology Alert: Green Roofs. [Online] US Environemntal Protection Agency. Available from <http://www.epa.gov/heatisland/mitigation/greenroofs.htm > [Accessed 5th February 2013].

DOE (2007) Chicago City Hall green roof project. [Online] US Department of Energy. Available from< http://egov.city ofchicago.org >[Accessed 17th February 2013].

D.O. Hall (1999) Photosynthesis. Sixth edition. Cambridge University press D.R. Henderson (2001) The Role of Buisness in the Modern World [Online] Institute of Economic Affairs. Available from <http://www.iea.org.uk/sites/default/files/publications/files/upldbook248pdf.pdf>[ Accessed 8th April 2013].

77

D. Rømø (2011) Green Roofs Worldwide [Online] Copenhagen. Available from < http://www.scpknowledge.eu/sites/default/files/R%C3%B8m%C3%B8%202012%20Green%20 roofs%20worldwide_0.pdf>[Accessed 15th March 2013].

D. Stanners, P. Bourdeau (1995) Europe's Environment: The Dobris assessment. Plant Growth Regulation [Online] September 1998, 25 (3), p 206 Available from<http://link.springer.com/content/pdf/10.1023%2FA%3A1017136600066.pd f > [Accessed 20th December 2012] Dutt et al. (2003) Challenges Urbanisation in the 21st Century. GeoJournal Library. 75, 2004. Page 304 EIA (2012) Consumption and Efficiency. [Online] US Energy Information Agency. Available from < http://www.eia.gov/> [Accessed 4th Janruary 2013] E. McLamb (2011) The Ecological Impact of the Industrial Revolution [Online] Ecological Communication Group. Available from < http://www.ecology.com/2011/09/18/ecological-impact-industrial-revolution/> [Accessed 18th December 2012] EPA (2012) Heating, Ventilation and Air-Conditioning (HVAC) systems.

[Online] US, Environmental Protection Agency. Available from< http://www.epa.gov/iaq/schooldesign/hvac.html> [Accessed 26th January 2013] EPA (2011) A Guide to Indoor Air Quality. [Online] US Environmental Protection Agency. Available from< http://www.epa.gov/iaq/pubs/insidestory.html#Intro1> [Accessed 27th January 2013] EPA (2013) Air pollutants. [Online] US environmental Protection agency.

Available from< http://www.epa.gov/oar/airpollutants.html> [Accessed 1st March, 2013].

EPA (2013) Albedo. [Online] US Environmental Protection Agency. Available from < http://www.epa.gov/heatisland/resources/glossary.htm> [Accessed 4st February 2013] EPA (2013) Trees and vegetation. [Online] US Environmental Protection Agency. Available form < http://www.epa.gov/heatisland/mitigation/trees.htm>[Accessed 4th February 2013].

EPA (2013) Urban Heat Island. [Online] US Environmental Protection Agency.

Available from < http://www.epa.gov/hiri/> [Accessed 3rd March 2013].

E.P. Odum (1971) Fundamentals of ecology. Third edition, New York, Saunders.

ESA (2011), UN Urbanisation Prospectus 2011. United Nations: Department of Economic and Social Affairs.

78

[Online] Available from: <http://esa.un.org/unup/> [Accessed 20th October 2012] EUP (2004) Noise. [Online] European Parliament Factsheet. Available from <http://www.europarl.europa.eu/facts_2004/4_9_5_en.htm> [Accessed 8th March 2013].

F. Bussotti et al (1995). Preliminary studies on the ability of plant barriers to capture lead and cadmium of vehicular origin. Aerobiologia 11 (1995) 11-18.

F. Dodds et al (2012) Review of implementation of Agenda 21 and the Rio Principles [Online] Sustainable Development in the 21st Century. Available from<http://www.stakeholderforum.org/fileadmin/files/Agenda%2021%20Rio%2 0principles%20Synthesis_Web.pdf >[Accessed 5th January 2013] F. Fay & C. Opal (1999) Urbanisation Without Growth: A Not So Uncommon Phenomenon. Policy Working research Paper 2412, London, Uk FHWA (2012) What is Sustainability? [Online] U.S. Department of transportation. Available from <https://www.sustainablehighways.org/296/whatis-sustainability.html> [Accessed 4th Janruary 2013] F. Kaltenbach (2008). Living walls, Vertical gardens – from the flowerpot to the planted system façade. [Online] Detail nr 12 (2008) 1454-1463. Available from< http://www.detail-online.com/architecture/topics/living-walls-verticalgardens-ndash-from-the-flower-pot-to-the-planted-system-facade-011477.html> [Accessed 9th April 2013].

F.K. Benfield et al (1999) Once There Were Greenfields: How Urban Sprawl is Undermining America's Environment, Economy, and Social Fabric. First edition. Natural resource Defence.

G. Grant (2006) Green Roofs and Facades. First edition. IHS - BRE Press G.M. Apte et al (2000), Associations between CO2 concentrations and sick building syndrome symptoms: An analysis of the 1994-1996 BASE study data, Indoor Air, summer 2000 10, pp. 246-257.

Greenpeace (2013) Solutions to Deforestation [Online] Greenpeace, USA. Avalable from <http://www.greenpeace.org/usa/en/campaigns/forests/solutionsto-deforestation/>[Accessed 5th January 2013] GRG (2012) Benefits of Green Roofs. [Online] Green Roof Guide, UK. Available from < http://www.greenroofguide.co.uk/benefits/>[Accessed 5th February 2013].

G. Wong et al (2010). Acoustics evaluation of vertical greenery systems for building walls. Building and Environment. 45, (2) (2010). pp. 411-420.

H. Akbari et al. (1997). Peak power and cooling energy savings of shade trees. Energy and Buildings 25 (1997) pp. 139–148.

79

H. Akbari & HIG (2005). Energy Saving Potentials and Air Quality Benefits of Urban Heat Island Mitigation. [Online] US Heat Island Group. Available from< http://heatisland.lbl.gov/> [Accessed 27th February 2013].

H.E. Landsberg (1981) The Urban Climate. First edition. Academic Press H. Lambers et al (2008) Plant Physiological Ecology. Second edition.

Springer H. Levin (1991) Critical building design factors for indoor air quality and climate: current status and predicted trends. Indoor Air [Online], (1). March 1991 pp.

79–92 Available from<http://onlinelibrary.wiley.com/doi/10.1111/j.16000668.1991.07-11.x/abstract> [Accessed 26th January 2013] H. Taha (1997) Urban climates and heat islands: albedo, evapotranspiration, and anthropogenic heat. Energy and Buildings 25 ( 1997) pp. 99-103 H.W. Smith (1976) Removal of atmospheric particulates by urban vegetation: implications for human and vegetative health. The journal of biology and medicine 50, Winter ,1977 IEA (2012) Carbon Dioxide Emissions From Fuel Combustion: Highlights.

IEA Statistics. 2012 Edition. Luxemburg, IEA Publications.

J.A. Summerville et al (2008). Community participation, rights, and responsibilities: The governmentality of sustainable development policy in Australia, Environment and Planning. Government and Policy, 2008, 26 (4), pp. 696 – 711 J. Blewitt (2008). Understanding Sustainable Development. First edition London, Earthscan J. Kibert & G. Bradley (2002), Buildings and Climate Change.

[Online] United nations Environment Programme. Available at: <http://www.unep.org/sbci/pdfs/SBCI-BCCSummary.pdf> [Accessed 5th January 2013] J. Lovelock (2010) The Vanishing Face of Gaia: A Final Warning. First edition. Penguin J. Mentens, D. Raes, M. Hermy (2006) Green roofs as a tool for solving the rainwater runoff problem in the urbanized 21st century? Landscape and Urban Planning. [Online] 77 (2006) 217–226. Available from< http://www.floradak.be/downloads/eng.pdf> [Accessed 25th March 2013].

J.L. Weisdorf (2005) From Foraging To Farming: Explaining the Neolithic Revolution. Journal of Economic Surveys [Online] 2005 19 (4). Available from<http://classes.uleth.ca/200701/anth1000b/foraging%20to%20farming.pdf> [Accessed 20th October 2012]

80

J.O. Lewis (1999) A green Vitruvius: Principles and Practice of Sustainable Architectural Design. First Edition. London,James and James (Science Publishers).

J. P. Bocquet-Appel (2011). When the World's Population Took Off: The Springboard of the Neolithic Demographic Transition. Science 333 (6042): July 2011, page 560–561.

J.R. Short (2012), Globalisation, Modernity and the City Routledge, Studies in Human Geography. First Edition. Oxon, Routledge Publishers.

K. Freeman (2008) Plants in Green buildings. Ambius White Paper. [Online] 2008,1. Available from < http://www.ambius.co.uk/learn/white-papers/> [Accessed 30th January 2013] K. Yeang (2007) Eco Skyscrapers. Third edition. Australia, The Images Publishing Group Ltd. K. Scott et al (1999). Effects of Tree Cover on Parking Lot Microclimate and Vehicle Emissions. Journal of Arboriculture. 25 (3). Summer (1999).

L.E. Glaeser (1998) Are Cities Dying?. Journal of Economic Perspectives, 12(2) Spring.1998. page 139-160.

L.H. Lilliana & C.Y. Jim (2013) Green-Roof Effects on Neighborhood Microclimate and Human Thermal Sensation. Energies. [Online] 2013, 6, pp.

598-618. Available from< www.mdpi.com > [Accessed 22nd February 2013].

L. Howard (1833) The Climate of London. [Online] International Association For Urban Climate. Available from< http://urbanclimate.org/documents/LukeHoward_Climate-of-London-V1.pdf> [Accessed 9th April 2013].

Lundholm et al (2010) Plant species and functional group combinations affect green roof ecosystem functions. PLoS ONE [Online] 5 (3) (2010), p. 9677.

Available from<http://dx.doi.org.ezproxy.leedsmet.ac.uk/10.1371/journal.pone.0009677> [Accessed 15th March 2013].

M.A. Benedict & E.T. McMahon (2002). Green Infrastructure: Smart Conservation for the 21st Century [Online] Sprawlwatch. Accessed from <http://www.sprawlwatch.org/greeninfrastructure.pdf. >[Accessed 27th March 2013].

M.D. Burchett et al (2001) Proceedings of Sixth International Conference on Indoor Air Quality, Ventilation & Energy Conservation in Buildings – Sustainable Built Environment [Online] Oct, 2001. 3, pp. 249-256. Available from< http://www.interiorplantscape.asn.au/Downloads/M_B_Papers/UTSIAQVEC_Jap_07-Oct_2007.pdf>[Accessed 30th January 2013]

81

M.D. Burchett et al (2006) The Potted Plant Microcosm Substantially Reduces Indoor Air VOC Pollution: II. Laboratory Study. Water, Air, and Soil Pollution [Online] 177 (2006): pp.59–80. Available from< http://www.urbangarden.co.nz/pdfs/potted-plant-microcosm.pdf> [Accessed 26th January 2013] M.D.Burchett et al (2010) Indoor Plant Technology for Health and Environmental Sustainability. Research Report 10024.

Horticulture Australia Ltd Meadows et al (1972) The Limits to Growth. First Edition. London, Universe Books.

Menzies et al (1993) The effect of varying levels of outdoor-air supply on the symptoms of sick building syndrome. New England Journal of Medicine 328, Spring 1993, pp. 821-826 M. Hough, (1995), Cities and Natural Process: A Basis for Sustainability.

Second Edition. Routledge.

M. Jacobs (1999) Sustainable Development as a contested concept, in Dobson A (ed) Fairness and Futurity: Essays on Environmental Sustainability and Social Justice, Oxford, OUP M. Kohler (2008) Green façades - a view back and some visions, Urban Ecosystems.11, (2008) pp. 423-436.

M. Oka (2005) Air Flow in Urban Areas. [Online] Green Design in the City.

Available from <http://www.greendesignetc.net/Flows_05_(pdf)/OkaMasayoshi_Air_Flow_in_U rban_Area.pdf >[Accessed 4th February 2013].

M. Ottele (2011) The Green Building Envelope Vertical Greening. Open Journal of Ecology. [Online] Netherlands (2011). Available from< www.repository.tudelft.nl> [Accessed 22nd February 2013].

M. Scholz (2004) Case study: Design, operation, maintenance and water quality management of sustainable storm water ponds for roof runoff.

Bioresource Technology, 95 (2004), pp. 269–279 M. Sanatmouris (2001) Energy and Climate in the Urban Built Environment.

First Edition, Routledge.

M. S. Jones (2002) Effects of UV Radiation on Building Materials [Online].

Building Research Association of New Zealand (BRANZ). Available from: < http://www.branz.co.nz/cms_show_download.php?id=cc222ceed21cb03b7a47d 69f8a3029efc07f91d9> M.Wilson et al (2003) Urban Air, indoor environment and human exposure Environment and Quality of Life. Report 23. Luxembourg. European Communities.

82

N. Berglind et al (2004). Road traffic noise and hypertension. Occupational & Environmental Medicine, 64(2), 2004 pp.122-126.

N. Dunnet & N. Kingsbury (2004) Planting Green Roofs and Living Walls.

First Edition. Oregon, Timber press.

N.H. Wong et al (2009) Thermal evaluation of vertical greenery systems for building walls. Building and Environment. 8 (5). August (2009).

NRDC (2012) The Consequences of Urban Stormwater Pollution. [Online] US Natural Resources Defense Council. Available from< http://www.nrdc.org/water/pollution/storm/chap3.asp>[Accessed 14th March 2013].

O.A. Seppänen & W.J. Fisk (2004) Summary of Human Responses to Ventilation. Indoor Air. [Online] Special issue, June, 2004. Available from<http://www.escholarship.org/uc/item/64k2p4dc#page-1>[Accessed 1st February 2013] O. A. Seppänen et al (2006), Ventilation and performance in office work. Indoor Air, 2006 .16, pp. 28-36.

O. Galor & O. Moav. (2002). Natural selection and the origin of economic growth Quarterly Journal of Economics. 117, pp. 1133-1192.

O. Ling (2005). Sustainability and cities: concept and assessment. [Online] Singapore. Available from < http://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=1513631 &fileOId=1513632> [Accessed 8th April 2013].

O.M. Vasquez (2009), Bioclimatic Architecture, Architectural design. First Edition. Monsa; Ill edition.

ONS (2012) The UK population: past, present and future [Online] Office for National Statistics, 1800-1900. Available from < http://www.statistics.gov.uk> [Accessed 18th December 2012] ONS (2012) The UK population: past, present and future [Online] Office for National Statistics, 1800-1900. Available from < http://www.statistics.gov.uk> [Accessed 18th December 2012] Oxford English Dictionary (2013) Ecosystem [Online] Oxford Dictionaries.

Available from <http://oxforddictionaries.com/definition/english/ecosystem > [Accessed 10th January 2013] P. Costa & R.W. James (1995) Constructive Use of Vegetation In Office Buildings. [Online] Plants At Work Association New Zealand. Available from< http://www.pawa.org.nz/index.php?option=com_content&view=article&catid=37: plant-care&id=31:constructive-use-of-vegetation-in-office-buildings> [Accessed 30th January 2013]

83

P.K. Beckett et al (2004). Deposition velocities to Sorbus aria, Acer campetre, Populus deltoides x trichocarpa `Beaupre, Pinus nigra and x Cupressocyparis leylandii for coarse, fine and ultra-fine particles in the urban environment. Environmental Pollution, 133(1), August 2004 pp. 157-167.

P.J. Owen (1994) Influence of botanic garden experience on human health Manhattan: Kansas State University, Department of Horticulture, Forestry and Recreation Resources.

R. Allen (2009) The British Industrial Revolution in Global Perspective: New Approaches to Economic and Social History. First Edition. Cambridge University Press.

RainforestFoundation (2007) The Congo Basin [Online] The Rainforest Foundation UK. Available from< http://www.rainforestfoundationuk.org/index> [Accessed 10th January 2013] R. Avissar (1996) Potential effects of vegetation on the urban thermal environment. Atmospheric Environment. [Online] 30 (3), February 1996, Pp. 437–448. Available from < http://www.sciencedirect.com/science/article/pii/1352231095000135> [Accessed 22nd February 2013].

R. Carson (1962) Silent Spring. First edition. London, Penguin R.J. Goodland (1975) The Tropical Origin of Ecology: Eugen Warming's Jubilee. Oikos. [Online] 26 (2) 1975, pp. 240-245. Available from <http://www.jstor.org/discover/10.2307/3543715?uid=3738032&uid=2&uid=4&si d=21102179275717 > [Accessed 4th Janruary 2013] R. Lawton (2002) Population and Society in Western European Port Cities, C.1650-1939. First Editon. Liverpool, Liverpool University Press.

R.M. Solow (1972) Criticisms of The Limits to Growth. [Online] Wikipedia.

Available from< http://en.wikipedia.org/wiki/The_Limits_to_Growth#cite_note24>[Accessed 9th April 2013].

R. Pitt et al (2000) Models and Applications to Urban Water Systems.

[Online] The University Alabama at Birmingham < http://rpitt.eng.ua.edu/Publications/StormwaterTreatability/pollution%20preventi on%20and%20stormwater.pdf> [Accessed 4th February 2013].

R. Sánchez-Rodríguez (2005) Urbanization and global environmental change.[Online] IHDP Report 15 .Bonn Available from<http://www.ihdp.org and http://www.ugec.org> [Accessed 8th April 2013].

R. Ubens (2010) Every Tree Counts: A Portrait of Toronto’s Urban Forest [Online] Toronto, Urban Forestry. Available from < http://www.itreetools.org/resources/reports/Toronto_Every_Tree_Counts.pdf>[A ccessed 27th March 2013].

R. Wright (2004). A Short History of Progress. First edition. Toronto, Anansi.

84

S. Ahmed & A. Bharat (2012) Wind Field Modifications in Habitable Urban Areas. Current World Environment 7(2), (2012) pp. 267-273 S. Brand (2009) Whole Earth Discipline. Atlantic Books SCI (2012) Stormwater Runoff [Online] National League of Cities. Available from <http://www.sustainablecitiesinstitute.org/view/page.basic/class/feature.class/L ESSON_OVERVIEW_STORMWATER_RUNOFF;jsessionid=9CDFF3961253B 08FBCC617555B4DEDCD > [Accessed 4th April 2013].

S.J. Gould (1997) Criticisms of Gaia. In J. Turney, Lovelock and Gaia: Signs of Life. New edition. Columbia University Press.

S, Mohammed et al (2012) Green Facades as a New Sustainable Approach.

Energy Procedia [Online] 18 ( 2012 ) pp. 507 – 520. Available from < http://www.sciencedirect.com.ezproxy.leedsmet.ac.uk/science/article/pii/S18766 10212008326> [Accessed 5th February 2013].

S. Peck, M. Kuhn (2003) Design Guidelines for Green Roofs [Online] Mortgage and Housing Corporation and the Ontario. Avaialble from < http://www.epa.gov/heatisland/mitigation/greenroofs.htm> [Accessed 17th February 2013].

S. Sandifer & B. Givoni. (2002) Thermal Effects of Vines on Wall Temperatures: Comparing Laboratory and Field Collected Data. [Online] Proceedings of the Annual Conference of the American Solar Energy Society.

Reno, NV. Available from < http://www.sbse.org/awards/docs/Sandifer.pdf>[Accessed 5th February 2013].

S. Sheweka & N. Magdy (2011) The Living walls as an Approach for a Healthy Urban Environment. Energy Procedia.[Online] 6, (2011), Pp. 592–599.

Available from < http://www.sciencedirect.com.ezproxy.leedsmet.ac.uk/science/article/pii/S18766 10211014792#> [Accessed 17th February 2013].

T.C Wang (1975) A study of bioeffluents in a college classroom. Ashrae Trans 81 (1) October pp. 32-44.

T. Fjeld et al. (1998): The effect of indoor foliage plants on health anddiscomfort symptoms among office workers. Indoor and Built Environment. 7 (1998) :pp. 204-206.

T.R. Malthaus (1798) The Principles of Evolution [Online ] Library of Economics and Liberty. Available from <http://www.econlib.org/library/Malthus/malPop1.html> [Accessed 4th Janruary 2013] T. Trainer, M. Grubb G. Meyer (1995) The Radical Implications Of The Limits To Growth Anlalysis For The Design Of Settlements. [Online] Australian Planner. Available from<

85

http://socialsciences.arts.unsw.edu.au/tsw/D55RadImpsForDesgnOfSettlm.html > [Accessed 9th April 2013].

T. Tryzna (2007). Global urbanization and protected areas: challenges and opportunities posed by a major factor of global change- and creative ways of responding. [Online] California: California Institute of Public Affairs.

Available from < http://www.mnf.unigreifswald.de/fileadmin/Geowissenschaften/geographie/angew_geo/Publikation en/delavega-et_al_2012_Biosphere_Reserves_in_an_Urbanized_World.pdf> [Accessed 8th April 2013].

UNEP (1992) Agenda 21. [Online] Environment and Development Agenda.

Available from<http://www.unep.org/documents.multilingual/default.asp?documentid=52> [Accessed 5th January 2013] UNFCCC (2007), Climate Change: Impacts, Vulnerabilities and Adaption in Developing Countries.

[Online] Available at: http://unfccc.int/resource/docs/publications/impacts.pdf [Accessed 23th October 2012] UN-Habitat (2012) The State of The Worlds cities 2012/2013: Prosperity of cities. Research Report. Kenya, United Nations Human Settlement.

USDA (2012) Nations Urban Forests Losing Ground. [Online] US Forest Service. Available from <http://www.fs.fed.us/news/2012/releases/02/urbanforests.shtml> [Accessed 20th December 2012] V.Bradshaw (2010) The Building Environment: Active and Passive Control Systems. Third Edition. John Wiley & Sons.

V.I. Lohr & C.H. Pearson-Mims (1996): Particulate matter accumulation on horizontal surfaces in interiors: influence of foliage plants. Atmospheric Environment 30,(14) Spring 1996. Pp. 2565-2568.

V. Nabholz (1997) A Discussion of Physical-Chemical Properties, Environmental Fate, Aquatic Toxicity, and Non-Cancer Human Health Effects of Polymers. [Online] US Environmental Protection Agency. Available from< http://www.epa.gov/opptintr/sf/pubs/AssessmentPolymers.pdf> [Accessed 4th February 2013].

Wargocki et al (1999) The affects of outdoor air supply in an office on perceived air quality sick building syndrome (SBS) symptoms and productivity. Indoor Air. [Online] 2000, 10 pp. 222-236. Available from< http://www.innenraumanalytik.at/Newsletter/wargocki.pdf> [Accessed 26th January 2013] W. Beckerman (1995) Small is Stupid: Blowing the Whistle on the greens.

London, Duckworth.

Â

86 Â

WBDG (2012) Materials [Online].Whole Building design Guide: A Program of the National Institution of Sciences. Available from: < http://www.wbdg.org/resources/materials.php > [Accessed 4th February 2013].

W. Brascamp (2005) A Quantitstive Approach to Human Issues in Horticulture.

HortTechnology [Online] 3(1) (2005) pp 106-107. Available from< http://horttech.ashspublications.org/content/15/3/546.full.pdf>[Accessed 10th April 2013].

WCED, (1987) World Commission of Environmental Sustainability Report.

[Online] Available at: http://upetd.up.ac.za/thesis/submitted/etd-12192007154637/unrestricted/01dissertation.pdf [Accessed 20th October 2012] WHO (2011) Air Quality and Health. [Online] World Health Organisation.

Available from<http://www.who.int/mediacentre/factsheets/fs313/en/index.html > [Accessed 27th February 2013].

Wikipedia (2013) Air Pollution. [Online] Wikipedia. Available from<http://en.wikipedia.org/wiki/Air_pollution>[Accessed 4th March 2013].

W.M. Adams (2001) Green Development: Environment and Sustainability in the Third World 2nd Edition. London, Routledge.

W. Tombling (2006) Affect of High Temperatures in the Workplace. [Online] Activair, USA. Available from< http://www.tombling.com/cooling/heatstress.html> [Accessed 1st February 2013] W. Pompeii (2010) Assessing the Urban Heat Island Mitigation Using green Roofs [Online] Department of Geography and Earth Science. Available from < http://www.ship.edu/uploadedFiles/Ship/GeoESS/Graduate/Theses/pompeii_thesis_100419.pdf>[Accessed 15th March 2013].

Y. Liu & D.J. Harris (2008) Effects of shelterbelt trees on reducing heatingenergy consumption of office buildings in Scotland. Applied Energy. [Online] 85 (2–3), February–March (2008), pp 115–127. Available from < http://www.sciencedirect.com.ezproxy.leedsmet.ac.uk/science/article/pii/S03062 61907000931#fig1> [Accessed 6th April 2013].

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Bibliography of Illustrations and Diagrams Figure 1. World population growth (billions) 1050-2050. [Online image] Available from <http://blog.dssresearch.com/wpcontent/uploads/2011/11/world_population_10 50_to_2050.jpg> [Accessed 18th April 2013] Figure 2 . Atmospheric CO2 Concentrations and Average temperature over past 1000 years. [Online image] Available from <http://www.art.ccsu.edu/Gallery/20082009/Sustainable/Graph%20wikimedia.orgwikipediacommons990CO2Temp.jpg> [Accessed 18th April 2013] Figure 3. Percentage of urban and rural population 1950-2050 [Online image] Available from <http://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Percentage_of_W orld_Population_Urban_Rural.PNG/800pxPercentage_of_World_Population_Urban_Rural.PNG> [Accessed 18th April 2013] Figure 4 – 23 [Scanned image] Available from: H. Falkenberg (2011) Interior Gardens. First edition. Germany, Birkhauser.

Figure 24. Earths reflective coefficient (Albedo). [Online image] Available from <http://www.ecocem.ie/img/albedo_science.jpg> [Accessed 18th April 2013] Figure 25. Albedo values for various types of planet surface. [Online image] Available from <https://encryptedtbn1.gstatic.com/images?q=tbn:ANd9GcRzRr9x63g5nbBq1J FEAdZ4ZH3WTjPegA1-nM4oqlMVGHkot04g> [Accessed 18th April 2013] Figure 26. Air pollutants, sources and effects. [Online image] Available from <http://www.pprc.org/hubs/area/HAP_sources.gif> [Accessed 18th April 2013] Figure 27. a) Isolated roughness flow, b) Wake interference flow, c) Skimming flow [Online image] Available from <http://www.greendesignetc.net/Flows_05_(pdf)/OkaMasayoshi_Air_Flow_in_U rban_Area.pdf> [Accessed 18th April 2013] Figure 28. Flow around a tall building, with lower buildings upwind. [Online image] Available from<http://www.greendesignetc.net/Flows_05_(pdf)/OkaMasayoshi_Air_Flow_i n_Urban_Area.pdf> [Accessed 18th April 2013] Figure 29. Hanging gardens of Babylon. [Online image] Available from<http://upload.wikimedia.org/wikipedia/commons/thumb/a/ae/Hanging _Gardens_of_Babylon.jpg/350px-Hanging_Gardens_of_Babylon.jpg > [Accessed 18th April 2013]

Figure 30. Extensive green roof, Vancouver, Convention Centre, Canada.

[Online image] Available

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from<http://www.golder.ca/en/uploads/projects/image-206.jpg> [Accessed 18th April 2013] Figure 31. Intensive green roof, ACROS building, Japan.

[Online image] Available from<http://upload.wikimedia.org/wikipedia/commons/b/b3/ACROS_Fukuo ka_2011.jpg> [Accessed 18th April 2013] Figure 32. Typical elemental composition of a vegetated roof. [Online image] Available from<http://www.sustology.com/uploads/greenroof%20xsect.jpg> [Accessed 18th April 2013] Figure 33. Interior/exterior heat exchange, traditional and green roof comparison [Online image] Available from<http://www.greenroofguide.co.uk/imgs/Illistrations/7-green-roofcomparison-v2.jpg> [Accessed 18th April 2013] Figure 34. The Osher living roof, California Academy of Science.[Online image] Available from<http://www.greenroofs.com/projects/pview.php?id=509> [Accessed 18th April 2013] Figure 35 & 36. Extensive green roof, 900 North, Michigan Avenue, Chicago.

[Online image] Available from<http://newshour.s3.amazonaws.com/photos/2012/10/03/900_North_M ichigan_Ave_photo_Scott_Shigleydesign_Hoerr_Schaudt_slideshow.jpg> [Accessed 18th April 2013] Figure 37. Living wall, Madrid, Spain [Online image] Available from<http://www.stylepark.com/dbimages/cms/patrick_blanc/img/p298694_488_336-1.jpg > [Accessed 18th April 2013] Figure 38 – 40 & 42 - 44 [Scanned image] Available from< M. Ottele (2011) The Green Building Envelope Vertical Greening. Open Journal of Ecology.[Accessed 18th April 2013] Figure 41. Extensive living wall, Vancouver, Canada.[Online image] Available from < http://greenovergrey.com/living-walls/images/green-wallvancouver-vertical-garden_000.jpg> [Accessed 18th April 2013] Figure 45. The Urban Heat Island, sources, process and effects at meso and micro scales. [Online image] Available from<http://2.bp.blogspot.com/Nc8sLF2KwjM/TmJg_6Sq18I/AAAAAAAAADo/A2ZQhxbN9r0/s1600/urban_ heat_island_processes.jpg> [Accessed 18th April 2013] Figure 46. Acid rain process and effects [Online image] Available from<http://optioneenvirochemblog1.files.wordpress.com/2012/03/acid.jpg > [Accessed 18th April 2013]

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Figure 47. Urban smog, Los Angeles [Online image] Available from<https://encryptedtbn2.gstatic.com/images?q=tbn:ANd9GcRUQVFAj31ljQ1TYr2zvUcLPqs7uL1r9 XlAbsSnMEejJtfQNFfo> [Accessed 18th April 2013] Figure 48. Urban air flows. a) Boundary Layer, b) Rural layer, showing mixed surface roughness.[Online image] Available from<http://www.accessscience.com/loadBinary.aspx?filename=757413FG002 0.gif> [Accessed 18th April 2013] Figure 49. Pressure and Decibel levels of anthropogenic noise pollution.

[Online image] Available from<http://www.savemotorsport.com/noise_clip_image001.gif> [Accessed 18th April 2013] Figure 50. Comparison of infiltration percentage of natural and impervious ground cover. [Online image] Available from<http://s2.hubimg.com/u/1260649_f520.jpg > [Accessed 18th April 2013] Figure 51. Principal contaminants of urban runoff. [Online image] Available from< http://www.nrdc.org/water/pollution/storm/chap3.asp> [Accessed 18th April 2013] Figure 52 & 53. Extensive use of vegetated roofs, Stuttgart, Germany. [Online image] Available from<http://24.media.tumblr.com/tumblr_l5numn7lZ01qzt7kko1_500.jpg> [Accessed 18th April 2013] Figure 54. Urban forest, Portland, Oregon. [Online image] Available from< http://media.oregonlive.com/oregonian/photo/2012/07/11277089standard.jpg> [Accessed 18th April 2013] Figure 55. Extensive urban forest, Toronto Canada. [Online image] Available from< http://www.sweetloveable.com/wpcontent/uploads/2011/03/Torontos-Urban-Forest2-600x254.jp> [Accessed 18th April 2013] Figure 56. Urban Bioswales. [Online image] Available from< http://www.svrdesign.com/blog/wp-content/uploads/Trenton34thNW+bioswale-cropped.jpg> [Accessed 18th April 2013] Figure 57. Urban Bioswales [Online image] Available from< http://www.thankyouocean.org/wpcontent/uploads/2008/07/reducingurbanrunoff.jpg> [Accessed 18th April 2013] Figure 58. Constructed urban wetlands, Beijing, China [Online image] Available from<http://www.domusweb.it/content/dam/domusweb/en/architecture/201 2/01/19/nature-as-infrastructure/big_371863_9436_DO1201040061.jpg > [Accessed 18th April 2013] Â

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1.1 Photosynthesis Photosynthesis is the process used by vegetation and other autotrophic organisms in which solar energy is converted into chemical energy, which is used as fuel in order to power the organism’s natural activities. During the process of photosynthesis vegetation absorbs carbon dioxide and water and converts it into carbohydrates in the form of sugars and water in the presence of sunlight. Oxygen is also released in the process as a waste product. The following is a generalised chemical equation of photosynthesis: 6 CO2 + 12 H2O + Solar Energy + Chlorophyll → C6H12O6 + 6 O2 + 6 H2O (Carbon dioxide + water + solar energy + chlorophyll → Carbohydrates + Oxygen + Water)

The process of photosynthesis is executed differently within various species, however in all organisms photosynthesis primarily begins with light energy derived form solar radiation. This light energy is absorbed by proteins known as photosynthetic reaction centers, comprised of green chlorophyll pigment (Figure 1) suspended in chloroplasts (Figure 2), an organelle found in the make up of every plant cell. During this light dependent reaction energy is used to remove electrons from water producing oxygen gas as a waste product and hydrogen ions creating a the compound (NADPH) Nicotinamide adenine dinucleotide phosphate. The excess light energy absorbed is then transferred to chemical energy in the generation of the compound adenosine triphosphate (ATP), which is used as energy, by the photosynthetic cells (Figure 3).

During photosynthesis the main product derived from the process is carbohydrate in the form of sugars. The sugars are synthesised from a series of light-independent reactions called the Calvin cycle. During the Calvin cycle, atmospheric carbon dioxide absorbed by the vegetation through the leaf stomata is integrated into existing organic carbon compounds, such as ribulose bisphosphate (RuBP) Using the ATP and NADPH manufactured by the lightdependent reactions. The compounds produced during this reaction are then reduced into triose phosphate, one of every six triose phosphate molecules is disconnected to form carbohydrates and the remaining five are then recycled back into the photosynthetic cycle to rejuvenate the RuBP compound in order to create a continuous cycle (Figure 3).

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Figure 1. Chlorophyll pigment.

Figure 2. Chloroplast organelle.

Figure 3. Photosynthetic process in a chlorophyll organelle.

J.S Carter (2004) Photosynthesis [Online]. Selected Science Education.

Available from: < http://biology.clc.uc.edu/courses/bio104/photosyn.htm> [Accessed 20/02/2013].

Figure 1. Chlorophyll pigment. (2010) [online image]. Available from <https://upload.wikimedia.org/wikipedia/commons/thumb/4/49/Plagiomnium_affi

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ne_laminazellen.jpeg/300px-Plagiomnium_affine_laminazellen.jpeg> [Accessed 20/04/2013] Figure 2. Chloroplast organelle. (2010) [online image]. Available from <http://media.web.britannica.com/eb-media/76/53076-00461A5272A.jpg>[Accessed 20/04/2013] Figure 3. Photosynthetic process in a chlorophyll organelle. (2010) [online image]. Available from <http://hyperphysics.phyastr.gsu.edu/hbase/biology/imgbio/c3cycle.gif>[Accessed 20/04/2013]

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1.2 Evapotranspiration The plant process of transpiration refers to the evaporation of water from the body of plants, principally from leaves, stems and floral structures. The capacity of plants to transpire water starts in the stomata. The stomata, usually situated on the underside of leaf surfaces are covered in pores which open and close through the mechanism of guard cells. Transpiration occurs through the stomatal pores (Figure 1) as a by-product during the diffusion of carbon dioxide from the air during the process of photosynthesis.

Figure 1. Transpiration through leaf surface The process begins as the flow of water driven by capillary action and potential differences in hydrostatic pressure from the roots reaches the leaf structure.

The pressure difference in the upper part of the leaf structure aids the diffusion of water out of the stomata and into the surrounding. The amount of water leaving the plant to the surrounding atmosphere is regulated by the stomatal opening (Figure 1). The rate of transpiration is influenced by a number of atmospheric condtions such as evaporative demand due to conditions humidity, temperature, wind and incident sunlight surround the vegetation, soil water supply and size and species of plant. Transpiration via stomatal tissue accounts Â

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for the majority of water loss thorugh the plant, however some water is also lost due to direct evaporation from the plant surface. The primary purpose of the process of transpiration is to evaporativley cool plants as the water vapour diffused into the surrounding atmosphere carries heat energy with it. The combined processes of evaporation and transpiration create evapotranspiration accounting for the movement of water from various bodies such as soil, vegeatattive canopys and waterbodies to the air (Figure 2), playing an integral part in the earths water cycle (Figure 3).

Figure 2. Individual

components of

evapotranspiration

Figure 3. The water cycle.

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National Council for Science and the Environment (2012) Evapotranspiration [Online].The Encyclopedia of Earth. Available from: <http://www.eoearth.org/article/Evapotranspiration > [Accessed 20/02/2013].

Figure 1. Transpiration through leaf surface. (2009) [online image]. Available from<http://www.pcsd.k12.ny.us/bwoods/Regents%20Biology/Chapter%2019% 20Plant%20Function/Chapte9.jpg >[Accessed 20/04/2013] Figure 2. Individual components of evapotranspiration. (2009) [online image].

Available from<http://upload.wikimedia.org/wikipedia/commons/thumb/8/80/Surface_wate r_cycle.svg/260px-Surface_water_cycle.svg.png> [Accessed 20/04/2013] Figure 3. The water cycle. ( 2009) [online image]. Available from<http://www.uvm.edu/~inquiryb/webquest/sp09/tgasperi/Pictures/watercycl e.jpg > [Accessed 20/04/2013]

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1.3 Shading Generally during the summer months, the amount of radiation transmitted through the vegetative canopy and reaching the surface below is around 1030% with the other 70% being absorbed by photosynthesis and a fraction being reflected back into the atmosphere. In winter the range of solar energy reaching the surface beneath vegetation is much wider, around 10-80% (Figure 1 & 2) (K Rakesh, S. Kaushik 2005). The extent of the amount of solar radiation which Is intercepted not only depends on climatic and seasonal conditions but also through differences in vegetation crown dimensions, tree phenology, leaf density and species.

Figure 1. Cross section of chloroplast showing light absorbed for photosynthesis and light reflected back to the atmosphere

Figure 2. Percentage of solar transmission during summer and winter.

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EPA (2013) Trees and Vegetation [Online].Heat Island Mitigation. Available from: < http://www.epa.gov/heatisland/mitigation/trees.htm> [Accessed 20/02/2013].

Figure 1. Cross section of chloroplast showing light absorbed for photosynthesis and light reflected back to the atmosphere. (2012) [online image]. Available from<http://3.bp.blogspot.com/Cv_a3q2RMuA/T3_XLemocZI/AAAAAAAAAyI/EfPWZgaNByc/s1600/Pic%2B2. png >[Accessed 20/04/2013] Figure 2. Percentage of solar transmission during summer and winter. (2012) [online image]. Available from<http://www.renovateyourworld.com/images/HowTo/IHouse/YardGarden/S ummerWinter2.jpg>[Accessed 20/04/2013]

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1.4 Dry Deposition According to aerosol physics, deposition refers to the process in which fine particulate material is deposited and collected on solid surfaces, therefore reducing the overall concentration of matter suspended in the atmosphere.

Deposition occurs through two main sub processes know as wet and dry deposition. Dry deposition occurs when particulate is intercepted (A), adheres to (B) or is absorbed by another element (C) (Figure 1). With reference to vegetation dry deposition occurs when particulate matter adheres to the various elements of plant life such as leafs, stems and the medium in which they grow.

The rate of deposition is affected by particulate size and varying climatic conditions. Large particulate matter tends to settle quickly through sedimentation, while plants more easily absorb the smaller particles.

Figure 1. Dry deposition of vegetation: A: Interception, B: Adherence, C: Absorption.

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Wikipedia (2013) Dry deposition [Online]. Deposition (aerosol physics).

Available from: < http://en.wikipedia.org/wiki/Deposition_(aerosol_physics) > [Accessed 20/02/2013].

Figure 1. Dry deposition of vegetation: A: Interception, B: Adherence, C: Absorption (2007) [online image]. Available from <http://www.scopenvironment.org/downloadpubs/scope21/images/fig5.4.gif > [Accessed 20/04/2013]

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1.5 Phytoremediation Phytoremediation refers to the biological capacity of certain plants known as hyperaccumulators to bioaccumulate, degrade,or mitigate harmless contaminants from soils, water, or air. The ability for this accumulation is derived from hypertolerance, the result of adaptive evolution of plant life in hostile environments over many generations. Phytoremediation covers a range of processes that vegetation uses in treating environmental problems; the three most effective in reducing indoor air pollutants are: Phytoextraction: Vegetation absorbs the pollutants through the root system and stores them in the root biomass and/or transports them up into the stems and leaves (Figure 1).

Figure 1. Phytoextraction.

Phytostabalisation: Â Vegetation stabalises and inhibits the pollutant from further activity over a long period of time for example vegetation imobilises the airbourne pollutant and provides an area surrounding its root system in which the pollutant can recipitate and stabalise and therefore remain dormant (Figure 2).

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Figure 2. Phytostabalisation.

Phytotransformation (Phytodegradtion): Vegetation metabolises the pollutant changing its chemical composition and breaking it down into a simple molecular form until it is rendered non-toxic (Figure 3).

Figure 3. Phytotransfromation (Phytodegradation).

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Wikipedia (2013) Phytoremediation [Online]. Phytoremediation. Available from: < http://en.wikipedia.org/wiki/Phytoremediation> [Accessed 20/02/2013].

Figure 1. Phytoextraction. (2009) [online image]. Available from<http://www.biologyonline.org/js/tiny_mce/plugins/imagemanager/files/boa0 01/phytoremediationf03.JPG >[Accessed 20/04/2013] Figure 2. Phytostabalisation. (2009) [online image]. Available from< http://www.biologyonline.org/js/tiny_mce/plugins/imagemanager/files/boa001/ph ytoremediationf07.JPG>[Accessed 20/04/2013] Figure 3. Phytotransformation (Phytodegradation). (2009) [online image].

Available from<http://www.biologyonline.org/js/tiny_mce/plugins/imagemanager/files/boa0 01/phytoremediationf09.JPG >[Accessed 20/04/2013]

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1.6 Vegetation Attenuating Noise Pollution Vegetation can reduce noise pollution through three principal techniques as follows: Absorption Reducing the reverberation time of travelling sound waves via absorption into the plant structure (Figure 1).

Figure 1. Absorption of soundwaves.

Diffraction At lower frequencies where the wave lengths of travelling sound is around a meter vegetation has the capacity to diffract sound waves because the leaf sizes are small in comparison to the wavelength of noise (Figure 2).

Figure 2. Diffraction of sound waves Â

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Reflection When the sound wave is of a higher frequency the leaf sizes may reflect the sound onto other surfaces that will then absorb the noise (Figure 3).

Figure 3. Reflection of soundwaves

Ambius (2012) Acoustic performance of plants [Online]. Why use plants in buildings?. Available from: < http://www.plants-­‐in-­‐ buildings.com/whyplants.php> [Accessed 20/02/2013].

Figure 1. Absorption of soundwaves. (2012) [online image]. Available from<http://missionscience.nasa.gov/images/ems/emsBehaviors_mainContent_ absorption.png >[Accessed 20/04/2013] Figure 2. Diffraction of sound waves (2012) [online image]. Available from< http://missionscience.nasa.gov/images/ems/emsBehaviors_mainContent_absor ption.png>[Accessed 20/04/2013] Figure 3. Reflection of soundwaves (2012) [online image]. Available from< http://missionscience.nasa.gov/images/ems/emsBehaviors_mainContent_reflec tion.png>[Accessed 20/04/2013]

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1.7 Vegetation Affecting Air Flow Vegetation can affect airflow through four principal techniques (Figure1): Guidance

Obstruction

Guidance

Deflection

Filtration

Figure 1. Vegetation affecting air flow.

Kofoed, N., M. Gaardsted (2004). Considerations of the Wind in Urban Spaces [Online]. Original Papers. Available from: < http://www.aensiweb.com/jasr/jasr/2012/5306-5310.pdf > [Accessed 20/02/2013].

Figure 1. Vegetation affecting air flow. (2012) [online image]. Available from< http://www.aensiweb.com/jasr/jasr/2012/5306-5310.pdf >[Accessed 20/04/2013]

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2.1 LOG ID Architects, BGW, Dresden, Germany LOG ID’s Green Solar Architecture pioneered by Dieter Schempp among others, primarily aims to use solar energy in a passive manner, in other words through the building itself and only using active technologies when this is not possible.

Since the 1980’s Green Solar Architecture has been making the most coherent use of vegetation as a technology in striving to rejuvenate the symbiotic and mutually beneficial relationship between plants, humans and architecture.

The basis for the fundamental influence of the use of vegetation in this type of architecture revolves around the climatic harmony created by natural plant functions such as photosynthesis and evapotranspiration. The interdisciplinary research and development behind these plant processes necessitated their use within buildings as they were found to; lower temperatures in summer, regulate relative humidity, improve indoor air quality, reduce noise levels (B. Wolverton 1980, V Lohr & C Pearson-Mimms 1996, P Costa & R.W. James 1995, M. Burchett 2004)

Figure 1. Front façade In BGW Dresden, vegetation was treated as a primary construction technology in the buildings architecture in order to utilise its climatic benefits discussed

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above (Figure 1). It was deemed necessary to provide adequate living space for plants, respectively in relation to overall costing and efficiency, therefore the typical division of winter gardens and semi public space was abandoned.

Instead the integration of plants throughout the space to create flowing transitions and to optimise their climatic benefits was used, for example the ground floor beds are situated directly behind the southern façade to make best use of their air conditioning advantages. In summer the indoor temperatures of the building were estimated to be around 6C above average outdoor temperatures, vegetation was used to provide controlled shade throughout the day, otpimised by evapotranspiration which provided a marked cooling effect.

The permeability of the internal layout allows the varied forms of vegetation to remove pollutants from the air, provide fresh oxygenated air and act as an acoustic cushion at all occupied levels (Figure 2 & 3).

Figure 2. Main atrium

Figure 3. Vegetation at all levels

There are a total of nine vegetated basins throughout the building, covering an area of around 170m2. The plants used are strategically selected with relation to their preferred climatic conditions. The beds that are directly exposed to the sun consist of “solar hungry” plants such as Eucalyptus, Acacias and Australian Silver Oaks. The beds in shaded areas consist of mastic shrubs, orange jasmine, leathery leaved bushes and small palms.

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Vertical climbing figs, evergreens, low bushes and an assortment of trees around 8m tall were used to provide shade for all occupied levels (Figure 4).

Figure 4. Assortment of large trees in atrium.

The interior organisation of the BGW headquarters building provides an operational example of the holistic use of vegetation in environmental control and aesthetic place making. The apparent success of this building to regulate and improve the internal building climate is a vindication of the application of independent theoretical scientific data from a range of resources.

Dieter Schempp (1997) LOG ID BGW, Dresden (Opus 30). Axel Menges Edition. Stuttgart/London. Edition Axel Menges.

Figure 1. Front façade. Scanned Image <Dieter Schempp (1997) LOG ID BGW, Dresden (Opus 30). Axel Menges Edition. Stuttgart/London. Edition Axel Menges>[Accessed 21/04/2013] Figure 2. Main atrium. Scanned Image <Dieter Schempp (1997) LOG ID BGW, Dresden (Opus 30). Axel Menges Edition. Stuttgart/London. Edition Axel Menges>[Accessed 21/04/2013]

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Figure 3. Vegetation at all levels. Scanned Image <Dieter Schempp (1997) LOG ID BGW, Dresden (Opus 30). Axel Menges Edition. Stuttgart/London.

Edition Axel Menges>[Accessed 21/04/2013] Figure 4. Assortment of large trees in atrium. Scanned Image <Dieter Schempp (1997) LOG ID BGW, Dresden (Opus 30). Axel Menges Edition.

Stuttgart/London. Edition Axel Menges>[Accessed 21/04/2013]

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2.2 Peter Costa (1995) An investigation into the Potential Benefits of Using Interior Vegetation as a Means to Reduce Noise Pollution Research was carried out by, Peter Costa, at South Bank University, London in 1995, to investigate the potential benefits of using interior vegetation as means to reduce noise pollution. Rentokil, provided access to previous research and data, technical advice, plant specimens and test sites to support this work.

The sound absorption coefficients of a number of plant species were measured in comparison to other building materials to quantify their acoustic effects. The higher the absorption coefficient the better the material is at absorbing the sound (Figure 1).

Plant species

Table of Absorption Coefficients Sound Frequency (Hz) 125 0.06

250 0.06

500 0.10

1000 0.19

2000 0.22

4000 0.57

0.21 0.13

0.11 0.14

0.09 0.12

0.22 0.12

0.11 0.16

0.08 0.11

0.09

0.07

0.08

0.13

0.22

0.44

0.13

0.03

0.16

0.08

0.14

0.47

Schefflera arboricola

-

0.13

0.06

0.22

0.23

0.47

Philodendron scandens

-

0.23

0.22

0.29

0.34

0.72

Bark mulch

0.05

0.16

0.26

0.46

0.73

0.88

Thick pile carpet

0.15

0.25

0.50

0.60

0.70

0.70

Plasterboard 0.30 0.15 0.10 0.45 0.75 0.90 Fresh snow, 100 mm Figure 1. Table of absorption coefficients.

0.05 0.95

0.04 0.95

0.05 0.95

Ficus benjamina Howea forsteriana Dracaena fragrans Spathiphyllum wallisii Dracaena marginata

Comparisons

The data suggests that vegetation does have an affect at attenuating to noise Â

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fluctuations. It also demonstrates that vegetation is more efficient at absorbing sound waves of higher frequencies than low frequencies for example Spathiphyllum wallisii (Peace Lily) notes a 0.44 coefficient at 4000Hz and a 0.09 coefficient at 125Hz. This supports the use of vegetation in buildings as high frequency noise causes most irritation to its occupants.

Costa, P. and James, R.W. (1995). Plants and their acoustic benefits.

[Online]. Plants in Buildings. Available from: < http://www.plants-inbuildings.com/acoustic.php >[Accessed 11th March 2013].

Figure 1. Table of absorption coefficients. (2012) [online image]. Available from <http://www.plants-in-buildings.com/acoustic.php > [Accessed 16/04/2013]

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2.3 The Osher Living Roof, California Academy of Sciences, San Francisco.

At the center of one of California’s largest urban parks, sits a 197,000 sq.ft. extensive living roof system, as part of the California Academy of Science’s LEED platinum green museum. Beneath the 2.5-acre living roof (Figure 1), a single structure measuring 410,000 sq.ft. houses the 12 different elements of the museum including an aquarium and an indoor rainforest. In addition to the living roof and other natural ecological elements, the building comprises of a variety of other sustainable features for example the use of 60,000 solar photovoltaic cells that source around 5-10% of the buildings energy needs and prevent the emission of over 180,000 Kg of greenhouse gases annually (GreenerBuildings, 2008).

Figure 1. Front façade and aerial view

Figure 2. View of central roof section

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The living roof sits 36ft in the air and comprises seven spherically shaped raised sections ranging in height 9-25ft, which surround the central glass ceiling (Figure 2). The raised mounds were designed to mimic the nearby San Francisco Mountains. Three of the large raised sections comprise slopes in excess of 60° which border the glass dome in a triangular formation. Two of the large raised spherical sections include several heat sensor skylights, which allow the interior temperature of the building to be maintained at an optimum level.

The varying topography of the living roof system created problems in terms of soil retention on the steep raised sections of the structure. Thus a biodegradable modular green roof system, known as the BioTray system was developed specifically for this project. The 48,000 BioTrays installed are 3 inches deep and 17 inches2 in area, creating a permeable, biodegradable and durable interlocking plant propagation unit. The BioTrays are constructed from coconut coir and natural latex, extracted from the waste product of the coconutindustry in the Philippines and tree sap respectivley. According to the ecological consultant on the project the inoculation of the coconut noir material with mycorrhizal fungi creates an optimized growing medium for plants as the fungi locks phosphorus into the soil supporting the development of healthy roots (P. Kephart). As the coconut coir is a material derived form natural process, following installation it decomposes over several years, allowing the plant roots time to propagate through the trays and interlock with the roof’s subsurface soil medium, forming a durable living area and allowing the soil on the steep raised mounds to remain locked in place.

Figure 3. Aerial view of roof.

Figure 4. View of principal dome.

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Figure 5. BioTray layout.

Figure 6. BioTray

The living roof was planted with over 1.7 million pants containing 9 different native Californian species in order to provide annual vegetative cover and attract wildlife such as birds and insects to increase biodiversity on the project.

The four perennial or constant vegetative species comprised sea pink (Armeria maritime), beach strawberries (Fragaria chiloensis), self-heal (Prunella vulgaris), and stonecrop (Sedum spathulitholium). The remaining five annual cyclic species comprised tidy tips (Layia platyglossa), miniature lupine (Lupinus bicolor), California plantain (Plantago erecta), California poppy (Eschscholzia californica), and California goldfield (Lasthenia californica).

The Osher living roof has a number of benefits that contribute to the internal and external elements of its urban situation. The six inches of soil used for plant propagation provide sufficient insulation maintaining interior temperatures at around 10F below that of a traditional roof construction in the Californian climate. The use of vegetation has reduced surrounding low frequency noise by around 40dBA, improving indoor noise quality and contributing to the attenuation of noise around the site. The vegetative cover of the roof contributes to the reduction of the UHI in the area, maintaining a surface temperature of around 40F cooler than a traditional low albedo material constructed roof. The large vegetated surface area adds to the reduction in air pollutants both internally and externally, as the central roof opening draws cool naturally conditioned, oxygenated air into the open piazza at the center of the structure allowing it to circulate throughout the building (Figure 7) The innovative design of the BioTrays allows the roof system to absorb up to 98% of all storm water, preventing 3.6 million gallons of stormwater runoff transporting

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pollutants from the nearby dense urban area into the ecosystem each year (CAS Press Release).

Figure 7. Ecological design features The Osher living roof provides a working model of the benefits of introducing the use vegetation into primary construction methods, in order to regulate the surrounding climatic conditions and produce a sustainable outcome. Although the Osher living roof covers a large expanse in a relatively open space, the theory behind the use of BioTrays can be applied on the varying topographical surfaces of densely populated urban areas.

Greenroofs (2010) California Academy of Sciences, Green Roof [Online].

The Green Roofs Project Database. Available from: <http://www.greenroofs.com/projects/pview.php?id=509> [Accessed 01/03/2013].

Inhabitat (2011) California Academy of Sciences, Green Roof [Online].

Architecture. Available from: < http://inhabitat.com/california-academy-ofsciences-green-roof/ >[Accessed 01/03/2013].

GreenSource (2013) California Academy of Sciences, Verdant Laboratory: A multi-faceted institution sheltered by an undulating green roof takes a holistic approach to sustainable design [Online]. The Magazine of Sustainable Design. Available from: Â

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<http://greensource.construction.com/projects/2009/03_California-Academy-ofSciences.asp>[Accessed 01/03/2013].

Figure 1. Front façade and aerial view (2010) [online image]. Available from < http://www.greenroofs.com/projects/calacademy/calacademy1.jpg> [Accessed 17/04/2013] Figure 2. View of central roof section (2010) [online image]. Available from < http://www.ced.berkeley.edu/courses/fa10/arch244//wpcontent/uploads/2010/09/CAS6-186.jpg > [Accessed 17/04/2013] Figure 3. Aerial View of roof (2010) [online image]. Available from < http://www.greenroofs.com/projects/calacademy/calacademy3.jpg> [Accessed 17/04/2013] Figure 4. View of principle dome (2010) [online image]. Available from <http://24.media.tumblr.com/tumblr_m5fdj9laU51r64zpvo1_500.jpg > [Accessed 17/04/2013] Figure 5. BioTray layout (2010) [online image]. Available from <http://postfiles14.naver.net/20111024_253/hanmiyi_1319437623663bxA7L_JP EG/IMG_4108.JPG?type=w2>[Accessed 17/04/2013] Figure 6. View of central roof section (2010) [online image]. Available from <http://www.greenroofs.com/blog/wp-content/uploads/2011/06/5BoroBioTrayBiodegradableModularSystem.gif> [Accessed 17/04/2013] Figure 7. Ecological design features (2010) [online image]. Available from <http://www.greenroofs.com/projects/calacademy/calacademy8.jpg > [Accessed 17/04/2013]

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2.4 A Comparative Study of the Thermal Performance of Vegetation on Building Surfaces An experiment was carried out in a residential zone of London during summer into the microclimatic benefits of using vegetation on building surfaces.

A North to South axis road, containing identical geometric building topography on either side was selected. Two opposing buildings one facing East and one facing West were used each containing vegetated external walls, composed of Virginia Creepers at a depth of 35cm.

The building containing the West-facing wall was partially covered with Virginia Creeper and partially uncovered leaving it in direct exposure of solar radiation.

Measurements were recorded over three separate days with varying solar radiation intensity and exposure, ranging from high temperate and clear, to warm temperate and clear, to cool and overcast respectivley.

Data loggers were fixed beneath the vegetative surface and at the same height on the exposed surface in order to record comparative temperature and humidity fluctuations. A separate data logger was fixed to the building containing the East-facing wall in order to obtain a larger scope of results.

Hourly temperature and humidity values were recorded at the Meteorological Centre in London as means of control.

Over the initial day of experimentation, peak temperatures of 41C and 34C were recorded on the exposed surface and vegetated surface of the Westfacing wall respectively (Figure 2). The recorded relative humidity values (Figure1) demonstrate that the vegetated surface had on average, a relative humidity value 9% higher than that of the exposed surface, this was believed to been to down to evapotranspiration. During the night the exterior humidity value increased overall due to nighttime cooling. Lower values of relative humidity were recorded beneath the vegetated surface in comparison to the exposed surface. These lower humidity values were believed to be due to a layer of warm air beneath the vegetated surface that remains trapped from diurnal temperature fluctuations.

During the second day of experimentation, peak temperatures of 42C and 25C Â were recorded on the exposed surface and vegetated surface of the Westfacing wall respectively. Differences in temperature and humidity on each surface were continually observed over the third day, however the variance in peak values was reduced due to the cool overcast climatic conditions.

The temperature recorded beneath the vegetation on the West-facing wall was marginally higher than that of the East-facing wall during peak hours, due to a layer of trapped warm air produced by higher daily temperatures.

The external surface of the exposed wall decreases in temperature at night, however it remains warmer than the ambient temperature due to heat stored from solar gains during the day.

Overall the results confirm the beneficial intervention of vegetation in creating a more comfortable internal microclimate and protecting the building surfaces by absorbing, shading and reflecting solar gains while increasing humidity levels near the building surface.

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Figure 1. Humidity measurements for West facing wall partially covered with vegetation.

Figure 2. Temperature measurements of different surfaces

G.A.C Cantuaria (1995). A comparative study of the thermal performance of vegetation on building surfaces. Architecture, City, Environment, Proceedings of PLEA 2000, Cambridge, UK page 312-313. James & James Ltd 2000.

Figure 1. Humidity measurements for West facing wall partially covered with vegetation. Scanned image < G.A.C Cantuaria (1995). A comparative study of the thermal performance of vegetation on building surfaces. Architecture, City, Environment, Proceedings of PLEA 2000, Cambridge, UK page 312-313.

James & James Ltd 2000.

Figure 2. Temperature measurements of different surfaces. Scanned image < G.A.C Cantuaria (1995). A comparative study of the thermal performance of vegetation on building surfaces. Architecture, City, Environment, Proceedings of PLEA 2000, Cambridge, UK page 312-313. James & James Ltd 2000. Â

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2.5 Ken Yeang (2007) Solaris Towers, SIngapore, Malayasia.

Ken Yeang (1948) is a Malaysian architect and author principally recognised for his use of deep green architectural design and urban masterplanning since 1971. Yeangs work can be distinguished from other green architects by his accurate and comprehensive ecological and environmental approach to design.

Ken Yeang is a world-renowned pioneer of ecological design and green urbanism, his most influential work is that applied to eco skyscrapers. Most recently Yeangs work explores the concept of ‘ecomimicry’, which refers to the synchronised design and construction of the human built environment with that of processes and biological structures found in natural ecosystems.

The Solaris towers, Singapore is one of Ken Yeangs more recent creations.

Solaris is located in the Fusionopolis hub of central Singapore's one-north business park, a high-density urban district. Constructed in 2011, the building sits on a 7,734m² site and comprises two tower blocks separated by a public, ventilated, glass-roofed atrium. The building sits 79m in height covering 15 and 9 storeys towers in height respectively. The overall floor area of the building is 51,282m²; the vegetated landscape area is 8,363m². The primary objective when designing the Solaris towers was based on Yeangs concept of ecomimicry and therefore instead of exchanging the existing natural ecosystem with that of hard urban built environment, the design sought to maximize habitable vegetated space in addition to various sustainable building technologies.

Figure 1. Front façade.

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Figure 2. Rear façade.

Figure 3. Aerial view of exterior.

The public atrium (Figure. 4) of Solaris comprises an inclined glazed operable roof that draws naturally conditioned air from the surrounding extensive vegetated areas and sunlight into the building in order to moderate temperature, humidity and indoor air quality of the interior climatic conditions. At the top of each tower sit vegetated roof areas and sky terraces (Figure. 5, 6) providing outdoor open space and a continual interaction with nature, increasing the overall of vegetated footprint of the building and also controlling radiative exchanges with the atmosphere and surface temperatures of the structure. The diagonal solar shaft emerges from the first tower block allowing sunlight to infiltrate into the interior environment; vegetated terraces within the solar shaft further improve the interior climatic conditions increasing air quality, regulating temperature and humidity and enhancing views up into the building from the street below.

Figure 5. Sky garden.

Figure 4. View of atrium.

Figure 6. Vegetated terrace.

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The Eco-cell (Figure 8) allows for the extension of sunlight, natural ventilation and vegetation into the basement and car-park levels below the building. The structure comprises a climate-responsive façade design originating from an analysis of Singapore’s east-west sun path, consisting of over 10km of solar shading louvers. The combination of vegetative shading and a climate responsive façade allows for habitable vegetated microclimates along the buildings exterior and further reduces radiative heat exchanges across the building’s structure, providing an extremely low External Thermal Transfer Value of 39 W/m2, reducing the amount of energy used for HVAC systems.

Yeangs concept of ecomimicry is further emphasised through the projects most innovative feature, a 1.5Km continuous vegetated armature (Figure 7), encapsulating the buildings façade and connecting the adjoining one-north Park at ground level and the Solaris basement Eco-cell. The armature has a minimum width of around 3m and comprises a flowing sequence of vegetated landscapes at all levels of the building. The continuity of the vegetated armature is an essential element of the project’s ecological design concept creating an extensive ecosystem in which organisms and plant species can interact enhancing biodiversity and contributing to the upkeep of both the buildings ecosystem and that of the surrounding urban area. The vegetated ramp also acts as primary regulatory technology through the capacity of its shade plants to passively cool the buildings façade and filter exterior air pollutants creating equilibrium between the artificial construction of the built form and natural ecosystem.

Figure 7. Vegetated armature.

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The overall vegetated area of the Solaris building will exceed the man made footprint on site with a ratio of around 108%, with 95% of the buildings total vegetated area being above ground level. The sustainable measures taken to construct this building provide an overall energy consumption reduction of around 36%. The use of an extensive rainwater harvesting system allowing 700m3 of water to be recycled for irrigation, combined with the capacity of the buildings vast amount of vegetation to store stromwater will reduce urban runoff by 95%. The incurred costs of the Solaris building were around 6.3% below industry standards. The building received a 97.5 Platinum certification rating from Singapore’s GreenMark program, making it Yeangs most successful project.

The Solaris building provides a successful, ecologically beneficial and cost effective model for the design of buildings and utilisation of vegetation as pa primary construction method in order to create a more inclusive sustainable urban ecosystem.

Figure 8. Ecological design features.

T.R.Hamzah, K Yeang (2012) Profile [Online]. T.R. Hamzah Yeang International Available from: < http://www.trhamzahyeang.com/profile/company.html> [Accessed 11th March 2013].

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NRI (2012) Solaris Fusionopolis, Singapore [Online]. Net Resources International. Available from: < http://www.designbuildnetwork.com/projects/solaris-fusionopolis/> [Accessed 11th March 2013].

CTBUH (2013) Solaris, Singapore [Online]. Council on Tall Buildings and Urban Habitat. Available from: <http://www.ctbuh.org/TallBuildings/FeaturedTallBuildings/FeaturedTallBuilding Archive2012/SolarisSingapore/tabid/3854/language/en-GB/Default.aspx > [Accessed 11th March 2013].

Figure 1. Front façade. (2012) [online image]. Available from < http://www.ctbuh.org/Portals/0/Feature%20Archive/Tall%20Building/2012/Solari s/Solaris_01.jpg > [Accessed 16/04/2013] Figure 2. Rear façade. (2012) [online image]. Available from <http://www.ctbuh.org/Portals/0/Feature%20Archive/Tall%20Building/2012/Sola ris/Solaris_07.jpg> [Accessed 16/04/2013] Figure 3. Aerial view of exterior. (2012) [online image]. Available from <http://www.ctbuh.org/Portals/0/Feature%20Archive/Tall%20Building/2012/Sola ris/Solaris_02.jpg> [Accessed 16/04/2013] Figure 4. View of Atrium. (2012) [online image]. Available from <http://www.ctbuh.org/Portals/0/Feature%20Archive/Tall%20Building/2012/Sola ris/Solaris_08.jpg> [Accessed 16/04/2013] Figure 5. Sky garden. (2012) [online image]. Available from < http://www.ctbuh.org/Portals/0/Feature%20Archive/Tall%20Building/2012/Solari s/Solaris_04.jpg> [Accessed 16/04/2013] Figure 6. Vegetated terrace (2012) [online image]. Available from < http://ecotanahmerah.com/wp-content/uploads/2012/07/solaris.jpg> [Accessed 16/04/2013] Figure 7. Vegetated Armature. (2012) [online image]. Available from < http://www.ctbuh.org/Portals/0/Feature%20Archive/Tall%20Building/2012/Solari s/Solaris_05.jpg> [Accessed 16/04/2013] Figure 8. Ecological design features. (2012) [online image]. Available from <http://www.designbuild-network.com/projects/7565/images/147673/large/05limage.jpg > [Accessed 16/04/2013]

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2.6 Buenos Aires Urban Heat Island: Intensity and Environmental Impact.

Buenos Aires is located along the western coast of the Río de la Plata estuary, Argentina. The metropolitan area extends for 4,000 km2, its topography is featureless with only minor differences in height of less than 30 m. The city population comprises more than 13 million inhabitants transforming it into one of the world’s mega cities. Its population grew steadily during the twentieth and the beginning of the twenty-first centuries, and from 1940 to 1960 the growth was accelerated by industrialization.

Figure 1. Buenos Aires popultaion increase 1895- 1991 This study provides data to distinguish one of the environmental impacts that relates to urban development, climatic factors and urban design attributes.

The UHI has been experimented on in many different regions using fixed and mobile stations distributed throughout an urban area. In this case mobile stations were chosen, as they provide more information on the temperature distribution at a fixed point in time and its relationship to different urban areas.

Seven simultaneous vehicular circuits were constructed, leaving from the city centre by differing routes and returning to the original point after 60 minutes. A 12km radius from the centre, reaching the motorway which separates Federal Capital from Buenos Aires was covered.

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Measurements were taken after 20:30 hours, as research has shown the UHI is much more intense at nighttime. The experimenters identified the location of the vehicle every 2 minutes, traffic conditions and street profile and evaluated the proportions of the street canyon. The temperatures were measured every 10 seconds using a data logger fixed 140cm above the vehicle, adapted to obtain direct airflow. The temperature was also recorded every 15 minutes at a fixed position near the river plate at a height of 26 meters. Temperatures at the domestic and international airports and the city observatory were also obtained for information on wind speed and direction.

The temperatures recorded automatically in the vehicles gave values between 10-14C during the circuits between 20:30 and 22:30, under cloudy, cold and windy conditions. During the measurement the wind speed was variable with Westerly gusts reaching 20m/s. Cool windy conditions have been found to reduce the UHI effect. Regardless of the variables the study showed a heat island with a difference of temperature exceeding 3K between the central area and the two main urban areas of Cordoba and Santa Fe, which combine heavy traffic and dense building development. The analysis of a series of infrared satellite images on the day also show an increase of temperature along the main urban transport arteries, which coincide with dense urban development.

The route taken by each vehicle was plotted on the plan of the Federal District together with the position at each time interval, urban character and the corresponding temperatures. Figure 2 shows the isotherms obtained with this data. Further temperature differences were also expected between dense inner suburbs and the surrounding rural area.

A second series of measurements were made two months later on a day with clear skies, bright sun during the day and little wind. These conditions are more favourable for intensifying the UHI, however the variation in temperature was very similar.

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Figure 2. Urban heat island intensity federal capital Buenos aires 1999

Figure 3. Isotherm of urban heat island Buenos aires 1999

M.J. Leveratto, S.D. Schiller, J.M. Evans (1999). Buenos Aires urban heat island: Intensity and environmental impact. Architecture, City, Environment, Proceedings of PLEA 2000, Cambridge, UK page 312-313. James & James Ltd 2000.

Figure 1. Buenos Aires popultaion increase 1895- 1991. Scanned image < M.J. Leveratto, S.D. Schiller, J.M. Evans (1999). Buenos Aires urban heat island: Intensity and environmental impact. Architecture, City, Environment, Proceedings of PLEA 2000, Cambridge, UK page 312-313. James & James Ltd 2000> [Accessed 16/04/2013] Â

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Figure 2. Urban heat island intensity federal capital Buenos aires 1999 < M.J. Leveratto, S.D. Schiller, J.M. Evans (1999). Buenos Aires urban heat island: Intensity and environmental impact. Architecture, City, Environment, Proceedings of PLEA 2000, Cambridge, UK page 312-313. James & James Ltd 2000> [Accessed 16/04/2013] Figure 3. Isotherm of urban heat island Buenos aires 1999 < M.J. Leveratto, S.D. Schiller, J.M. Evans (1999). Buenos Aires urban heat island: Intensity and environmental impact. Architecture, City, Environment, Proceedings of PLEA 2000, Cambridge, UK page 312-313. James & James Ltd 2000> [Accessed 16/04/2013]

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2.7 The Impact of Shelterbelt Trees on Heating-energy Reduction To measure the impact of shelterbelt trees on the heating and presumed energy reductions of a building, a computational simulation method was employed.

This is because complete investigations are expensive, time-consuming and complicated when researching heating-energy savings caused by shelterbelt trees, as it would require two identical office buildings; one with a shelterbelt and one without located in the same area to be monitored.

Research had shown that the open-plan office with a large glazed facade tends to be the mainstream modern design for office buildings nowadays, therefore it was decided to develop a naturally-ventilated, open-plan office model for this study to simulate energy savings and provide data that could be accurately applied to modern industry.

Figure 1. Wind rose for Edinburgh over one year.

Vegetated shelterbelt For this study, data was collected on average weather conditions in Edinburgh to predict the potential sheltering effect of vegetation. According to the annual

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wind rose of Edinburgh (Fig. 1), the prevailing wind in Edinburgh primarly originates from the southwest. Therefore, it was decided to: •

Situate the shelterbelt trees South West of the protected building in a line angled 150° from north. This angle was based on the results of Finbow (1988), demonstrating that shelterbelt trees oriented at 150° from North required less heating energy than that at 135° from North (M Finbow 1988).

•

Design the shelterbelt trees to consist of one row of deciduous trees 1.2 times the height of the building and of the same length of the perimeter of the building, to provide adequate shelter and allow sufficient solar gains to enter the building during the wintertime (Fig. 2). The distance between the shelterbelt and the building was selected to be five times the height of the trees. Shrubs were planted between trees to avoid any vertical gaps.

•

Select shelterbelt trees to have a medium porosity of around 40% to provide adequate wind-speed reductions over a long distance

Figure 2. Arrangement of shelterbelt trees relative to building.

The simulated-office model was a two-storey, open-plan office building comprising 17 zones in total including: 8 for office space, 2 for corridors, 3 for

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staircase and toilets, 3 for ceiling and 1 for the roof. The building plan and the zones are shown in Fig 3.

Figure 3. Plan view of the test model building and the divided zones.

The office was occupied between 9:00–18:00 hrs from Monday to Friday. In order to achieve an adequate comfort condition for building users, the heating system was started at 8:00hrs this maintained a temperature of 22 °C during the occupied period and at 15 °C during the unoccupied period from October to April. All other zones were maintained at 12 °C at all times.

Two weather-data files were prepared for the simulation.

1) Original hourly weather-data, representative of Edinburgh’s typical weather conditions.

2) Modified hourly weather-data taking the sheltering effect of trees into account. Generated based on the wind-speed reduction profile developed in Section.

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By recording the heat-energy savings of the office model with the use of the two weather-data files respectively, a quantitative estimation was made through comparison of the results of both simulations.

Results and Conclusion Over a 24-h period, variations of the: wind speed, external convectivecoefficient, air-change rate, convective heat-loss through opaque and glazing parts in zone unit-j were recorded and compared between the sheltered and unsheltered conditions (Fig. 4). The graph shows that the presence of the shelterbelt trees caused the wind speed to decrease. Figures 4b & 4c demonstrate the effects of reduced wind-speed on the reduction of external convective-coefficient. The results show the decreased external convectivecoefficient had a more substantial impact on the convective heat-loss through the glazed area of the building (Fig. 4d & 4e), showing that energy saving benefits of shelterbelt trees will be more effective on buildings with large glazed exteriors.

Figure 5 demonstrates the significant reduction in monthly heating loads in unitj, with the use of shelterbelt trees. For example, in February, a saving of 631 kWh was recorded with the use of shelterbelt trees.

Fig 6 shows a summary of the heating-load/m2 of floor area needed for the office model and the energy breakdown for both sheltered and un-sheltered variables, along with their savings incurred. The table shows a saving of 3.64 kW/m2 of floor area on the heating load with the use of shelterbelt trees.

The resultant percentage savings are shown in Fig 7. It was found that a substantial energy-saving of 18.1% of the total heating-load, 17.6% decrease in heat loss through air infiltration and 7.8% decrease in the convective heat-loss through building façade was implemented with the use of shelterbelt trees.

Overall the results of the study successfully demonstrate that shelterbelt trees do have the capacity to reduce the energy consumption of a building.

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Figure 4. Hourly variations of wind speed, external convective coefficient, air change rate and convective heat losses through opaque and glazing parts in the zone unit-j over a 24-h period.

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Figure 5. Monthly heating-loads for the zone unit-j between sheltered and unsheltered conditions.

Simulation condition

No sheltered condition Sheltered condition Saving

Heating load (kWh/m2)

Heat losses through the building (kWh/m2) Infiltration

Convection

20.06

22.21

Opaque 10.28

Glazing 14.03

16.42

18.29

9.83

12.94

3.64

3.92

0.45

1.09

Figure 6. Reduction of heating-energy consumption caused by shelterbelt trees from October to April.

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Figure 7. Percentage reductions in heating load, air filtration and convective heat-loss through opaque and glazing areas due to shelterbelt trees.

Y. Liu & D.J. Harris (2008) Effects of shelterbelt trees on reducing heatingenergy consumption of office buildings in Scotland. Applied Energy. [Online] 85 (2–3), February–March (2008), pp 115–127. Available from < http://www.sciencedirect.com.ezproxy.leedsmet.ac.uk/science/article/pii/S03062 61907000931#fig1> [Accessed 6th April 2013].

Figure 1-7. [Online image] Available from<http://www.sciencedirect.com.ezproxy.leedsmet.ac.uk/science/article/pii/S 0306261907000931> [Accessed 15th March 2013]

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2.8 A City in a Garden, Singapore.

The island city-state of Singapore is located 85 mi North of the equator (1° 14 N, 103°55 E), on the southern point of the Malaysian peninsula. The city is approximately 270mi2, comprising a population of around 5.3 million people (Singapore Department of Statistics, 2012). Singapore has witnessed a growth into one of the most affluent urbanised regions in Asia, due to its strategic location for global trading. Preceding the British colonisation and subsequent increase in population and trade in 1819, Singapore was no more then a dense vegetated rural area comprising 80% lowland forest, 5% freshwater swamp vegetation, 13% coastal man-groves and the remaining 2% consisting of small rural and costal settlements, however this vegetated land was soon removed and by the 1880’s around 7% of Singapore’s original forested area remained (Lum 1999, Cantley, 1884). This trend in rapid urbanisation continued through the 1900’s replacing almost all of Singapore’s vegetated land with hard urban infrastructure. With this rapid urbanisation came a variety of environmental problems that have been discussed in the main body of this dissertation (UN urbanisation prospectus 2012) It was not until the 1960’s and the transition into Singapore’s independence, that Prime Minister Lee Kuan Yew proposed the integration of ecological concepts in order to relieve the pressures created by urbanisation and thus improve the quality of life in the city. This facilitated the development of Singapore into “A city in a garden” (Nparks 2012).

As Singapore covers a relatively small land area of around 270mi2 its large population of 5.3 million people creates a very dense, compact area with little space for introducing green infrastructure. However careful planning and integration techniques has allowed for a reciprocal increase of vegetative cover with economic and population growth, committing 9% of the total land area to parks and nature reserves. For example during 1986 to 2007 Singapores population grew by a staggering 68% from 2.7 million to 4.6 million people, despite this rapid population growth during the same period of time vegetative cover increased from 35.7% to 46.5% (Figure 1).

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Figure 1. Percentage of vegetative cover 1986 and 2007 The various bodies of the Urban Redevelopment Authority (URA) contributing to the greening of Singapore created a master plan outlining and guiding the vegetative development of the city from 2003. The master plan consisted of a variety of techniques in which to utilise green infrastructure divided into 6 categories as follows.

Regenerate Urban Parks and Streetscapes.

A plan for the distribution of a network of both large and small expanses of urban parks, with a guideline of 0.8ha of green space per 1000 population provision, comprising a cluster of varying ecosystems including wetlands, tropical rainforests and wide areas of open green space to provide a holistic experience in which humans and ecosystems can function as one. For example, the Jacob Ballas Childrenâ&#x20AC;&#x2122;s Garden (2007) part of Singapore Botanic Gardens was designed as a green play leisure park for children, the HortPark (2008) designed as green hub for horticulturalists and other projects such as the Fort Canning Park designed as a venue for arts and culture within the city.

Singapores network of urban parks provides a multi use space in which to mitigate the environmental problems created by its urbanising population whilst involving urban residents and creating a green thinking community.

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Figure 2. Urban park Optimise urban space and infrastructure Singaporeâ&#x20AC;&#x2122;s urban parks discussed above are linked via seven major pathways comprising over 120mi of connecting vegetated routes, which serve to encourage recreational walking, jogging and cycling and remove the need for motor vehicle use. The vegetated paths create a closed loop system enhancing the actual use of vegetation and perception of green space throughout the city.

Figure 3. Vegetative network and park Â

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Figure 4. Vegetative enhancement of anthropogenic infrastructure Enrich urban biodiversity Singapore is a city rich in biodiversity, which is ever increasing with the integration of urban vegetation, for example species which were once thought to be extinct such as the Oriental Pied Hornbill, are now rejuvenating strong colonies due to the lush green environment. Due to Sinagapores location, it provides a foundation in which to enrich the nearby Indo-Malayan rainforest, in this context a government adopted policy to legally safeguard essential native ecosystems was put into place. With the influence of this government policy research has been implemented to create a long-term sustainable strategy in which to conserve the quality and prevent the effects of urbanisation on four existing nature reserves. The four nature reserves cover an area over 3,000 hectares comprising 4.5% of Singaporeâ&#x20AC;&#x2122;s total land area making it one of the only cities to containing such environmentally rich ecosystems in a n urban setting. The integration of urban parks and vegetated pathways also provides an ideal situation to enrich biodiversity within the urban area, creating new dynamic ecosystems and encouraging the influx of native wildlife.

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Enhancement of landscape and horticulture industry The URA have developed a range of programmes to increase standards of workmanship within the landscape and horticultural industry. With the creation of The Centre for Urban Greenery and Ecology (CUGE), 6,000 local works have been trained in order to preserve and enhance the intergrated green infrastructure, streamline industry operations, increase productivity and create new solutions in urban greening to ensure its life long sustainability.

Engage and inspire communities Part of the master plan involves striving to engage the urban residents of Singapore into the concept of creating a garden city by promoting the appreciation of natural ecosystems and horticulture in order to create a likeminded community. Several programmes have been created in order to implement this notion, for example, In 2006 alone, over 1,000 guided walks, educational talks, events were used to generate enthusiasm around the subject, further more the Community-in-Bloom (CIB) project has introduced more than 250 gardening groups within the urban community.

The Garden by the Bay

Figure 5. Gardens by the bay Â

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Finally Singaporeâ&#x20AC;&#x2122;s most influential project, which encapsulates the entire theory behind the concept of creating a garden city is the establishment of the world class Gardens by the Bay. Completed in 2012, the 101ha vegetated expanse comprises three waterfront horticultural themed gardens; Bay South Garden, Bay East Garden and Bay Central Garden. Bay Central garden provides a 2mi of waterfront promenade comprising various vegetative forms, however the development of bay central is ongoing. Bay East Garden covers an area of 32ha creating a 1.2mi promenade frontage that borders the Marina Reservoir. Bay East garden was designed as a sequence of tropical leafshaped expanses, each comprising its own vegetation specific design, character and theme. The use of vegetated aquatic expanses is implemented with relation to surrounding climatic conditions in order to create a regulated microclimate within the site, optimising the use of natural plant processes.

Bay South garden is the largest of the three covering 54ha in area. The design of the garden was facilitated by the shape of an orchid, representative of the countries national flower. The conservatories lining the waterfront represent the shape of the orchid flower, the leaves create the various landforms surrounding the conservatories. The various pathways represent the shoots of the plant while secondary roots are represented via water, energy and communication lines.

Figure 6. Garden by the bay conservatories. Â

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The conservatories comprise two primary spaces, the flower dome and the cloud forest and represent an energy efficient model of sustainable construction technologies. Â The Flower Dome covers an area of 1.2ha and is the larger of the two, creating a warm dry interior climate and containing plants found in the Mediterranean and other semi-arid tropical areas. The decomposed plant matter or biomass created by the vegetation in the flower dome is used to power a steam turbine, which generates on site electricity to maintain cool temperatures within the biome. The cloud forest conservatory covers an area of around 0.8 ha and is designed in a way that mimics cool moist conditions representative of tropical mountain regions between 1000 - 3000m above sea level, for example climatic conditions similar to those found in central South America. The cloud forest features several large vegetated features including a mountain, waterfall and a variety of plant life. Together the two conservatories boast around 220,000 plants of species from every continent across the globe making it one of the most concentrated, biologically diverse areas in the world.

Figure 7. The flower dome

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Figure 8. The cloud forest Another primary feature of the Gardens by the bay project consists of 18 treelike structures that dominate the Gardens' landscape. Known as supertrees, the vertical gardens range between heights of 25 - 50 m in height, comprising a host of different functions such as planting, shading and working as environmental engines providing power, ventilation and naturally conditioned air for the surrounding ecosystems. The supertrees are mechanical man made sturcutres designed to mimic the processes of real trees. The supertrees comprises several different communities of plant life such as exotic ferns, vines and orchids. Solar photovoltaic panels are fitted to provide a source of energy for anthropogenic functions such as lighting, in this way they mimic the process of photosynthesis. Further more the supertrees collect rain water for use throughout the site in the same way plants intercept and absorb surface run off and use it for plant processes for example transpiration. In addition the supertrees function as a HVAC system drawing cool, purified air into the conservatories.

Figure 9. The supertrees

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Figure 10. The supertrees structure.

The Gardens by the Bay project establishes Singapores support in creating a fully functioning, sustainable urbanised city. The project has been designed with the environment in mind, not only introducing varying forms of vegetation, but also creating anthropogenic structures into that suffice both ecological and man made needs. The Gardens by the bay project therefore provides a fundamental and current project that supports the use of vegetation as a primary technology within urban areas to achieve a more sustainable enevironement.

Figure 1 – 10. [Online image] Available from <http://www.homedsgn.com/2012/06/26/gardens-by-the-bay-by-grantassociates-and-wilkinson-eyre-architects/> [Accessed 25th March 2013] N Cantley (2008). Biodiversity in Singapore. [Online] BGCI Singapore Available from<http://www.bgci.org/resources/article/0585/> [Accessed 25th March 2013]

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CSC (2013) A City in a Garden. [Online] Civil Service College Sinagapore.

Available from<http://www.cscollege.gov.sg/Knowledge/Ethos/World%20Cities%20Summ it/Pages/08A%20City%20in%20a%20Garden.aspx>[Accessed 25th March 2013]

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