**1. Introduction**

In recent years, cities are faced with new concepts and environmental problems that began to appear. Gaining a global dimension, these concepts and problems have made multilateral cooperation and international coordination necessary for a permanent solution to these issues. So, to prepare the necessary legal infrastructure, all countries of the world are unavoidably engaged in an intense agenda. Sustainability, urban renewal and sustainable urbanisation are

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among the issues discussed. In 1972, 'United Nations Human Environment and Development Declaration', the first global assessment on the environment was adopted in Stockholm. Later in 1987, the sustainable development concept was defined for the first time in the Brundtland Report prepared by the World Commission on Environment and Development and has been widely used since then. In addition, 'sustainability principles' that were accepted at the Rio conference held in 1992 and the Habitat-2 City Summit in 1996 in order to create liveable environments have made sustainable urbanisation a prominent issue to be solved also in our Turkey as in other countries. Due to globalisation, change is inevitable, and today a 'planned change for sustainability' is still required.

Majority of the world's population now live in cities, and the number of people living in the countryside is steadily decreasing every day. Because of the population growth and unplanned settlements in urban centres, the available resources are running out and natural habitats are undergoing changes. In other words, failure to meet the growing need for housing in urban areas leads to unplanned settlements in a way that threatens both the identity and liveability of the city. In addition, this type of construction has brought with it the land zoning and infrastructure problems. This process has also accelerated the destruction of green areas, agricultural areas and coastal areas. And the places, where unhealthy, dilapidated and illegal buildings are intense, create visual pollution as well as become a potential threat to the health of the people living in them and the fabric of cities.

Especially, with the rapid restructuring and uncontrolled population growth that emerged after World War 2, natural systems have been ignored and an uncontrolled consumptionoriented development process has emerged. Adoption of a consumption-oriented lifestyle rather than production raises concerns for the future of cities and the life of their inhabitants. The capitalist, political, technological and industrial developments at the end of 1960s have significantly disturbed the ecological balance. And according to Özmehmet, this is the main reason for the inability to establish the correct link between development and the environment [1].

Urban spaces should not be considered only as a space consisting of buildings, but also as a social and cultural centre where social events take place. Therefore, due to the significant impacts of urban areas on the society and human behaviours, their design should also include the social and cultural aspects in addition to the physical dimension. As there is not a particular perception of space, it is considered as a concept of place that is constantly changing and renewed together with those living in it [2].

When looked at the urban transformation projects in the world, cities seem to have different regeneration processes from each other according to their own internal dynamics due to the impact of globalisation. Intervention strategies of the developed and developing countries include different contents from each other, and the cities that have completed their regenera‐ tion eventually force the other cities into this process. So, local governments attaching importance to the implementation of urban transformation want to create quality urban environments, renew the city's image and raise their status and position. For example, Canada, Norway, Switzerland, Sweden and Australia are among the countries that apply the ecosystem successfully in the urban transformation projects, the protection of natural resources and the use of renewable energy sources. In this respect, today Sweden is a model country with its capital Stockholm, chosen as the ecological capital of Europe in 2010.

Because of the oil crisis that appeared in the 1970s and 1980s, Sweden has renewed its national energy policy. In this context, it has made a great effort to discover new energy sources find new methods for the isolation of the buildings and develop energy-saving systems. Conse‐ quently, today Sweden's dependence on oil is decreased by 90% for heating and electricity production. In this process, it has planned the things to be done for sustainable living, taken necessary measures and implemented an ecology-based transformation model. Stockholm's Hammarby Sjöstad district is now renewed with this approach. The project has established an infrastructure that enables the recycling of all waste underground. In addition, divisions have been formed, where organic waste, paper type materials and the garbage unsuitable for recycling are collected separately. At certain times of the day, garbage collected in waste collection points is pulled down. By solar energy, energy and sustainable use of water are supported, dirty water is treated and reused, and the surface water is collected in artificial ponds. In addition, high heat-insulated buildings are constructed, and renewable energy sources are used instead of fossil fuels. While the organic waste is taken to fertilizer production centres, the other garbage is burned to produce energy for central heating systems. Besides, biogas is obtained from waste liquid in the treatment plant, and used in stoves in homes and municipal busses. In short, 'Hammarby model' is proposed as a new model for urban trans‐ formation in some countries (China) [3].

On the other hand, there are many countries where people still ask the following or similar questions to each other: Why don't we take the example of ecological-based models of urban renewal throughout the country? Why do we usually perceive urban renewal only as the housing production policy or the work of providing functional changes? And how long will the new buildings constructed within the scope of urban transformation be able to preserve their sustainability?.

Urban renewal concept, which is not yet fully seated in Turkey, emerges with different names in world literature. Urban renewal in different countries is formed by the interaction of different variables and called by different names. These applications contain the meanings defined as urban clearance, urban renewal, urban renaissance, urban revitalisation, urban redevelopment, urban regeneration, urban conservation, urban rehabilitation and urban gentrification.
