The ever-increasing growth of world population, as some believe, has adversely and often disastrously affected the natural habitats of each globe. Uncontrolled and irregular consumption of fossil energies, destruction of forests and the extinction of faunas and plant species have been considered as consequences of them. Concern over the future environment on earth and its natural reserves is an undeniable truth, the thing that has attracted most attentions in the world. Man's activities on earth has, on one hand, ending eared the opportunists and possibilities of coming generation and on the other hand threatened the cities where people have selected as their chief places of performances and where the natural reserves and resources are consumed in great volumes.
Sustainability has been defined as"meeting the needs of today without compromising the ability of future generation to meet their needs."It means thinking about our behavior in a big context – recognizing that our choices have a profound effect on our global environment and our future, and attempting to mitigate the negative impacts. A commitment to sustainability is a commitment to creative and responsible action.
"Sustainability refers to the ability of a society, ecosystem, or any such ongoing system to continue functioning into the indefinite future without being forced into decline through exhaustion … of key resources."
"The word sustainable has roots in the Latin subtenir, meaning to hold up or to support from below. A community must be supported from below – by its inhabitants, present and future. Certain places, through the peculiar combination of physical, cultural, and, perhaps, spiritual characteristics, inspire people to care for their community. These are the places where sustainability has the best chance of taking hold."
Sustainability requires integrated decision – making that takes into account economic, ecological, and social impacts as a whole.
However, the green principles purposed are not intended as a set recipe that must be followed, but are put forward as a reminder of the issues that many designers ignore. Nevertheless, the headings that follow for a green architecture to emerge.
Principle 1 : conserving energy : A building should be constructed so as to minimize the need for fossil fuels to run it.
Principle 2 : Working with climate : Buildings should be designed to work with climate and natural energy sources.
Principle 3 : Minimizing new resources : A building should be designed so as to minimize the use of new resources and at the end of its useful life, to form the resources for other architecture.
Principle 4 : Respect for users : green architecture recognizes the importance of all the people involved with it.
Principle 5 : Respect for site : A building will"touch – this – earth – lightly"
Principle 6 : Holism : All the green principles need to be embodied in a holistic approach to the built environment".
Sustainable city is a place where people live, work and prosper in a vibrant community of communities. In such a community, sustainability is achieved through community participation and the reconciliation of short and long term economic, social and ecological well- being.
• Sustainability is a direction rather than a destination. A sustainable city is one that protects and enhances the immediate and long – term well being of a city and its citizens, while providing the highest quality of life possible.
To ‘ sustain ‘ means to keep going. When a musical note is played, the meaning is unmistakable. With reference to landscape planning it is unclear. On a geological time scale, mountains rise and fall, species evolve and become extinct. The ant has sustained its physical form and way of life for hundreds of millions of years. What would it mean for a human society to be sustainable ? Affordability, Sustainability and Solubility have meaning only in defined circumstances. Salt is soluble in water but not in oil. A house can be non – affordable for most of us but easily purchased form Bill Gates ‘ pocket money. Sustainability makes sense only as a comparative. Labeling one city, or land use practice, ‘ Sustainable ‘ and another as ‘ non – sustainable ‘ is meaningless. The illustration below, reproduced from an essay on Eco – Cities in Tom tunner’s City as landscape illustrates the concept of relative sustainability.
A city with high inputs ( of energy, food, water, etc. ) and high outputs ( of thermal pollution, sewage, vegetable waste etc. ) is less sustainable than a city of the same size but with lower levels of input and output. This usages accords with the circumstances in which the concept of sustainability was introduced, in the 1970 s. The world was thought to be running out of resources. It hasn’t happened on the input side. But rich societies ‘ hatred of pollution has grown and provides a strong reason for making our towns more ‘ sustainable ‘ in the defined sense.
Improving the relative sustainability of a city requires an evaluation of those features which affect its pattern of inputs and outputs. This is likely to include earth, water, vegetation, building types, transport systems and spatial organization. One can then assess the potential for change through landscape planning. Two of the main challenges are the attainment of sustainable landscape objectives in the densely built city core, which is often historic, and the need to engage communities in a desire for sustainable cities and the consequent changes that will ensue. The achievement of sustainability objectives, in cities which were built on less – sustainable principles, is a complex process. The social physical and biological systems in urban areas are as complex as natural systems. Sustainability planners need to study, model and make proposals for the urban landscape at all scales and levels, in time and space, and beyond the usual of there generations.
City Principles of sustainability:
1. Today's decisions must not compromise the choices our children and future generations.
2. We are all accountable for our individual and collective actions.
3. Resources must be used fairly and efficiently without compromising the sustainability of one community for another.
4. Using renewable resources is encouraged and supported, while the use of non renewable resources should be minimized.
5. Renewable resource consumption should not exceed the rate of regeneration.
6. Strong collaboration and open communication between the public, the business sector, and all levels of government are important.
7. We value cultural, economic, and environmental diversity.
8. A community should provide a safe, healthy, and viable setting for human interaction, education, employment, recreation, and cultural development.