Economic development with no environmental control leads to an ecological or environmental degradation which adversely affect the quality of life. An ecosystem is a distinct area in the biosphere, where living and non living things interact within and between each other to produce a sustainable environment. Eco-architects have designed responsive spaces in the temperate climates based on eco-design concepts and it is believed that Bangladesh being in the tropical area is better placed to tap the ecological resources in their built environment design.
Eco-Design and Built Environment
In a nutshell, the eco-design is designing the built-environment as a system considering the ecological footprint of the area. The outlook on urban quality is changing nowadays, as a part of general shift in cultural values: their life style and pattern of living, nevertheless it concluded that outdoor spaces so to say open spaces of any type; spacious-non spacious, spectacular-non spectacular, formal-informal that is in or around the settlements, shape or contribute towards the liveliness of a city- the effect is enhanced when it is green and there is biodiversity of local plants.
The urbanization bonanza and market forces are blind folding us to the reality of the many ways in which the world around us is diminishing and emaciating. As cities are growing at a very faster rate, so the huge open spaces become ever more important for the well being of the urban dwellers. This is, as we experience today, more true of Dhaka, hundreds of public open spaces of different sizes were either partly or fully lost to building structures. Like any other sustainable city, Dhaka needs a huge stock of open spaces for urban services or utilities and circulation besides space needed for different public function and recreational activities. It is known that for a healthy city we need a right balance and proportion of built-up open spaces. It is found that there is a correlation between biomass in an area and it has a soothing effect on the environment and the sustainability of urban open spaces in terms of the pattern of socio-recreational activities in that area.
Cities are not universal in character nor do they have universal requirements. Thus, the variation in shape, size, layout, treatment, and development of urban open spaces is an offshoot of physical, socio-cultural, political and economic factors. Time and historical layering also play an important role on the open space configuration of the city. Thus, different localities of a city have different set up of open space situation.
The image of Dhaka is not derived from its concrete parts like building, roads etc. it is much deeper and more fluid, that is, its people, pattern of spaces and activities therein, the relationship between the living and nonliving part of its environment, time, space and the people. Any space in an urban area outside the buildings constitutes urban open space and the design and management of these spaces are crucial to urban sustainability and image. A common notion is that ecosystem or biodiversity or eco-design is something outside the city boundaries, whereas ‘green open space’, ‘parks’, ‘gardens’ etc are found within.
As cities grow ever more densely developed, so the remaining green spaces grow ever more important for the well being of the cities’ inhabitants. At present Dhaka city is almost a jungle of concrete blocks, there is hardly any open space or water body left. To create accessible open spaces now mean many structures are to be torn down in different localities. This proposition is neither practical nor feasible. Thus it can be argued, the design of existing green and open spaces- for the most part, urban parks – should receive attention equal to that of the cities’ buildings. However their status is required to be determined first.
The next important factor to remember is that the man himself is an important part of community and if the community is not in the state of balance the man himself will suffer as much as any other community. The most important factor in the list is perhaps the responsibility that the architect/ planner have for the long term development of built environment. This includes factors such as traffic planning for low emissions, urban typologies that promote compact solutions with high service levels while maintaining green and other spatial qualities, provision for mixed uses and integration of social classes and cultural groups. The available open spaces are required to be organized judiciously to maximize its response.
Evaluation Criteria for Ecosystem of Urban Open Spaces
An ecosystem is any spatial part or organizational unit, which includes living organism and non-living substances, interacting to produce and exchange of materials between the living and nonliving parts. Without the sun, nothing would happen on this earth. Its light, its warmth and its power enable plants, animals and human beings to blossom, grow and flourish. Without its light there would be no colors. It provides the energy that keeps everything alive – an unimaginable 4270 billion kilowatt hour every day. It would take 480 years for the world to use up the electricity produced by one day of solar energy. Or put in another way: the sun sends the world’s energy requirements for a whole year to the earth every three minutes. So why design something that is incongruent with ‘Nature’? Nature is what we have, not made. It not only produces plants, soil, stone, water, air but also nourishes animals and man.
The tree is an organic-architectonic system consisting of a foundation, the roots, a column, the trunk and a spatial network of branches. In the case of deciduous trees leaves are an additional summer feature, covering the bare winter structure. The biodiversity contributes towards natural and social sustainability, plants and water is the true ingredients. All the earth’s oxygen was and will be produced by plants and trees. Plants consist of up to 95 % water, and man and other animals of up to 60-70 %. Water is in constant metamorphosis and circulation. It is the principle element of natural life, as every living thing on the earth derives from it. There are plain and plump trees, low, squat trees but also bizarrely expressionist and large baroque tree domes. There are narrow slender trees (cypresses, poplars). There are trees that strive steeply upwards and trailing trees. Leaf roofs, tree domes, forest cathedrals, groves.
A tree has become involved with a spot on the earth; it has fixed itself there firmly. Here it will stay and grow, it is exposed to everything, wind, sun and snow, nesting birds, gnawing roe-deer, carving and sawing men: It is patient and pliant. This is what a designer needs, to organize a space that is functionally responsive.
A comprehensive (multidisciplinary) approach of planning is needed for stable urban system. The concept of ecosystem and biodiversity in the built environment design has been assessed and inferred that these can be successfully achieved at urban level by using place based environmental policy planning, that is local context and species needs due attention. Instead of confrontation we need cohabitation with nature for sustainable living. Open space are an important element of built environment which provide vibrancy and sustainability to a city. Ecological approach to design and manage these spaces is crucial to the sustainability of urban environment.
The Planning Concepts Effecting Urban Open Spaces
An ecological approach to the designing and handling open spaces are essential to the sustainability of our urban environment. Ecological footprint can be partially revived by the creation of Green grids or Ecological Urban Corridors, Ecological Urban Nodes or Green Pockets or Vegetated Roofs and Water Bodies.
Eco design and Planning
A common perception is that ecosystem or biodiversity or eco-design is something outside the city boundaries, whereas `green open space’, ‘parks’, `gardens’ etc are found within. The intensified pressure of population and the urbanization progression creates encroachment, leading to housing, circulation and other purposes on these open spaces.
Through analysis, thoughtful design and vigilant management of the development process and natural forces, even the largest structures can further the cause of a more harmonious assimilation of the built and natural environments. Eco-design approach does not reject high technology, but it is based on an ecological moral imperative “take least from and dump least into the environment”. The environment desires to be in a state of equilibrium for sustainable living and the utility value of biodiversity which provides equilibrium can be divided into four categories: goods, services, information, and psycho-spiritual uses. First of all, biodiversity can be seen as a goods (or a resource) that can be consumed or useful by humans, and therefore should be protected. The second category is the wide variety of services offered to us by a healthy ecosystem (Table-1). Green plants, for example, replenish the oxygen in the atmosphere and eliminate carbon dioxide. Fungal and microbial life-forms in the soil decompose dead organic material and play a vital role in recycling plant nutrients. Table 0l lists some of these services.
It includes not only the number of species but also the relationships that occur between living and non-living organisms and the biodiversity levels one considers when the concept of eco-design arises. The patterns branch of biodiversity refers to the spatial structure, allocation and movement (if any) of tile components. The third branch consists of the processes by which the biotic and abiotic components of an ecosystem interact (Table-2). This traces important interdependencies among the components and allows scientists and urban designers to predict how the ecological “balance” of the system might be disturbed by natural or human phenomena. The concept of right element in the right place and context, contributes towards sustainability of built environment.
The Challenge and the Goal – Sustainability: Sustainability is a simple idea. It is based on the recognition that when resources are consumed faster than they are produced or renewed, the resource is depleted and eventually used up. In a sustainable world, society’s demand on nature is in balance with nature’s capacity to meet that demand.
When humanity’s ecological resource demands exceed what nature can continually supply, we move into what is termed ecological overshoot. According to a report (World Resources 2000-2001, People and Ecosystems: The Fraying Web of Life, World Resources Institute, the United Nations Environment Programme, the United Nations Development Programme, and the World Bank) in addition to the growing depletion of non-renewable resources such as minerals, ores and petroleum, it is increasingly evident that renewable resources, and the ecological services they provide, are at even greater risk. Examples include collapsing fisheries, carbon-induced climate change, species extinction, deforestation, and the loss of groundwater in much of the world.
We depend on these ecological assets to survive. Their depletion systematically undermines the well being of people. Livelihoods disappear, resource conflicts emerge, land becomes barren, and resources become increasingly costly or unavailable (Fig). This depletion is exacerbated by the growth in human population as well as by changing lifestyles that are placing more demand on natural resources.
Environmentally Appropriate Processes:
Globalization has given us the freedom to adapt to newer possibilities. When it comes to the Global options of materials and techniques of Constructions we need to make our approach more scientific, respecting to the law of nature through its ecological context in this age of accelerated degradation. Increasingly one is realizing that architectural processes and planning practices have ecological consequences that significantly degrade the environment.
Most materials have high energy consumption during their manufacture and extraction process (Embodied Energy). Implicit the measure of Embodied Energy of building materials are the associated environmental impacts. Large amount of ever increasing greenhouse gasses are produced by these modern building materials which damage the urban air quality and are responsible for climate change. In a sustainable development perspective, we must address the quality and sustainability of our use of natural resources and ecosystems, threats of global change, and the impact of production and use of energy, which is essential to our economies and to our way of life, and also centrally important in environmental problems. Selection of appropriate elements for organizing the built-environment is, therefore, essential for environmental sustainability.
The traditional architecture however always took advantage of the natural environment and searched for practical solutions for long term grains and better environmental adaptation. Unfortunately, architecture today seems to be a mere play of fanciful borrowed global faced treatments. Knowing well that these models do not fit into our ground realities, we are still bent upon building IGLOOS in the desert. We adopt meaningless measure like banning the use of timber. This has encouraged the use of alternative materials like plastics, aluminum and other metals whose production process throw much more pollutants in our environment (Table-3). In recent years, the construction industry world wide has witnessed a trend towards environmentally responsive facilities, called eco properties. These structures carry the environmental theme throughout, from the positioning of building to maximize the natural assets benefits, to the careful selection of construction materials. A green property uses resources wisely, incorporating energy, water recycling and waste reduction techniques into the daily operations. Emphasis is laid on energy efficiency, resource conservation and environmental commitment.
Every materials used in a typical modern building is the product of energy intensive processing – all consuming vast quantity of power in their manufacture (embodied energy). These materials have to be dug out from the ground, cut from the forest or fields, or created by human technology. All these processes use energy.
w For extraction of material
w Process and manufacture
w Transportation cost
w Energy for production of capital equipment
w Disposal of waste
The manufacturing process also releases toxic affluent into water and hazardous chemicals into the atmosphere. The manufacture of Portland cement for example is responsible for on estimated 4% of the green house gases. It is interesting to note that the total energy consumed in building materials of a luxury hotel is about three times the energy consumed by a running hotel annually. Of course it is impossible to build with no environmental impact, but it’s our responsibility to minimize the damage. Process of development therefore becomes important in the question of sustainability.
Ecological Footprint and Theory of Partitioned Matrix
The ecological footprint is a resource management tool that measures how much land and water area a human population requires to produce the resources it consumes and to absorb its wastes, taking into account prevailing technology. Much of the body of analysis and synthesis within the realm of sustainable architecture has focused upon the physicality of the built environment, leaving the complex relationship between culture, climate and place largely undisturbed. For an architectural proposition to represent a truly sustainable design solution, reference to the cultural domain must be implicit.
In a world dominated by the culturally decontextualized homogeneity demanded by globalization, many contemporary architectural design propositions that purport to be Sustainable, ignore the specificity of the cultural dimension. It is clear that globalization is not only an economic condition but holds (anti) cultural aspirations deep within. In that sense, International Modernism provides a paradigm for globalization. Furthermore, International Modernism provides an iconography that represents globalization. The glass and steel tower – so beloved by modernism – has become the symbol of economic success, both at a corporate and nation-state scale. At its root, it is clear that International Modernism had very clear cultural aspirations. The form of dwelling cannot be understood only by a consideration of the technique and Material used. It is first of all necessary to be aware of how the principles of the local group are applied, and what kinds of work are performed by this group, and in which roles. There is much to learn from Architecture before it became an expert’s art. The untutored builders in space and time demonstrate an admirable talent for fitting their buildings into their natural surroundings.
Looking at the global economy today, one has to be increasingly aware of energy as a scarce resource; the need for architects to design for a sustainable future becomes a self-evident imperative. Here lies a likely trump card for affirming theoretical respectability: the design of energy-efficient enclosures has the potential to transform architectural design from being an uncertain, apparently whimsical craft, into a confident science. The theory for the design of the tall building might then be one that derives from energy conservation.
A ‘green’ approach means that a balance must be achieved between organic and inorganic components to achieve a balanced eco-system. Traditional approaches by architects tend to try to ‘add on’ environmental features and thus miss opportunities for ‘passive’ approaches which minimize the impact on the environment. Schemes should aim to create ‘cities in the sky’, in contrast to traditional high rise which merely stacks floors one on the other, creating compartmentalization. The challenge is to design in an organic and humane way with both horizontal and vertical integration. Ecological design is still in its infancy. It is complex; requiring understanding of the effects one factor has on another. Because of past experience of under funding and failure to maintain adequate management arrangements in the public sector, this type of approach might fail. It will be an uphill battle to persuade tenants that radical approaches will enhance their quality of life. Many planning authorities need convincing of the benefits of developing taller buildings.
Architect Ken Yeang has been involved in the design of skyscrapers for the past 25 years. Why skyscrapers? And why green? Skyscrapers occur largely because of urban growth and rural migration. When that happens a city can only go sideways, eating into arable or other vegetative land. The way to save that arable land is to intensify cities by going upwards. He pointed out that, as Corbusier argued, skyscrapers have a smaller footprint and can provide more open space. The United Nations uses the argument that it lowers transportation costs and thus energy consumption.
There are many definitions of green design. There are contradictions between existing technology and nature. The first starts with predetermined objectives whereas nature has a discernment of what is there rather than starting with fixed goals. Existing technology looks to process efficiency and mechanistic approaches while nature looks at systemic harmony and an organic, holistic approach. The aim is to try to bring this together. Architecture is like a prosthetic device – it is artificial, and man made. The present built environment is mostly inorganic. What is needed is to start with the ecological system and using organic with inorganic components to achieve a balanced ecosystem. Ar. Ken Yeang started to look at different ways of achieving this.
One way is horizontal greening either through putting all the greenery in one place similar to traditional city squares. The alternative is vertical greening allowing migration of species through it. He went on to explain some of the issues and techniques that have to be followed. For instance, planting has to follow the solar path and requires hardy species – as is being considered for the Elephant and Castle scheme. It is important to understand the system of energy and environment. There are four basic categories to be considered: passive mode which avoids any electro-mechanical devices; mixed mode using some electro-mechanical devices; full mode perhaps using environmental controls; and finally productive mode, which involves the building being used to generate its own energy through photo-voltaics and other systems. With ecological design the strategy has to optimize all the passive options, before progressing to the mixed and other options.
Most ecological designers define eco design as designing with minimal impact on the environment but it is a battle that you can never win. But there are ways to include biodiversity. One approach is the ‘landscaped bridge’ which immediately improves the environment, encouraging species to move in from nearby green areas. It involves working in a different way – it means putting the buildings in a park rather than building first and creating the park after. It is important to understand that ecological design requires an understanding of a site’s carrying capacity. It involves ‘sieve’ mapping devices to achieve minimum impact on the existing natural environment. It requires analyzing the current species and vegetation and deciding what to bring in. As well as simply introducing nature, schemes must involve the systematic greening of the man-made environment.
Ecological design is a knowledge-based approach – analyze the information, evaluate it and change the design. One of the issues is recycling which must be used at every stage of construction- it should take into account replacement rates – and incorporate lifetime energy costing. It must include water recycling, perhaps using collectors and filters to make the rainwater potable. Thus ecological design is very complex. Separately laying different options of sustainable design and than overlaying all of them together to see the intersection or overlapping areas of aspects and thereby assessing the eco sustainability is the short definition of ‘partition matrix’ approach of design to indicate how one factor impacts on another and the effect of architecture on the environment. It shows that you cannot change one thing without changing the others. There is still a need to develop ecological design criteria and global monitoring. Basically ecological design is in its infancy. Ecological designers are still experimenting with a range of systems and there is a long way to go.
The Environmental Crisis- Need of a Sustainable Open Space
In the hot humid climate of Bangladesh open spaces including water bodies, both natural and man made, are more than an integral part of life and living. They play an important role in the physical and social activities performed by the inhabitants of the city. Green open spaces when articulated with water bodies become visually more attractive and climatically more responsive. Such spaces develop a natural sustainability of the city. Natural sustainability is rooted in retaining existing ecosystem and cultural relevance.
Like any other sustainable city, Dhaka needs a huge stock of open spaces for urban services or utilities and circulation besides space needed for different public functions and recreational activities. Open green Spaces in the city act like its lungs besides being used as active recreational and leisure areas for its citizens. Circulation areas also, though serving active purposes, provide some breathing spaces to the urbanities. Spaces provided for the utilities also serve some passive needs. We, therefore, must realize that open spaces have a direct impact on the urban environment and general physical, mental and social health of the urban dwellers.
Unfortunately, developments within Dhaka city are aimed at accelerating only the direct economic return. Our developer have made the Word “development” synonymous with destruction of environment but it is not so. There will be need for constructions or cutting trees for development activities but that should be done in a planned manner with planned replenishment of the nature to keep the biomass in a balanced state. An appropriate balance of living and nonliving parts of the environment needs to be promoted to maintain a sustainable ecosystem, because a stable urban morphology is always alive.
Architects seem to think that the important thing is that buildings look ecological. We must consider a large number of environmental factors that concern the architect. When we talk about the environment friendly urban system the following factors should be included:
w Design for low health risks;
w Design for low energy use;
w Design that do not deplete the bedrocks;
w Designs using local materials ( that do not generate long transport );
w Designs that are well adapted to climate;
w Designs adapted to changes ( to avoid destruction and new building when uses change )
w Planning for the long term development of the built environment towards sustainability;
w Design that facilitates neighborly co-operation around environmental tasks;
w Designs that look environment friendly (to stimulate ecological thinking).
The first four factors do not require any further explanations. The problem is mainly to find out exactly which designs that provides for good health, little use of energy etc. In order to depletion of bedrock, all kinds’ metals should be avoided, but if constructions are such that metal components can be recycled, then of course this renewable material can be used. In addition, building materials that use a lot of energy for its productions, such as cement, should be avoided, unless construction elements can easily be dismantled and reused. For this purpose, new construction techniques are required, e.g. disconnectable joints between construction elements.