Building arises from the need to establish adequate environmental and social conditions to accommodate human activities in a given space under conditions of good habitability. Housing constitutes not only a fundamental right defined by the Spanish and Andalusian Constitution and by the Law on the Right to Housing, but also a determining factor in social organization as it is the basic element of the urban environment and, therefore, of the spatial structure of society.

The recommendations of the European Union and specifically the Leipzig Charter, are aimed at not generating new housing and creating active policies for the rehabilitation of the current housing stock. Ensuring the success of the housing rehabilitation processes also includes the following aspects:

decent and comfortable place to develop.

The rehabilitation policy of centers and neighborhoods centered on people and that uses constructive instruments only as a tool for social intervention and collective improvement is the only one that ensures the sustainability, the viability, of the social systems that live in these neighborhoods. Paradoxically, although it is only a surprise at first glance, the social identity linked to a territory and its resources is a fundamental basis for the urban system to function under parameters of physical sustainability. When we consider the space where we live as our own and know its strengths and weaknesses, it is possible to develop individual and collective behaviors that conserve natural and built capital with a long-term vision.

term. Sustainability, in a broad sense, thus becomes the greatest expression of shared common destiny.[2]​.

Europe is a largely urban society and the urban has always had a considerable imprint on the culture and way of being and ways of life of Europeans. Andalusia is no exception and its territorial model tends to organize and balance the territory by promoting processes of cooperation and cohesion, relying on these urban networks.

Territorial planning constitutes the most valuable tool to address these challenges since it provides the framework in which to inscribe urban processes, valuing them from their relationship with the rest of the territorial components and contextualizing them in a certain biophysical and cultural framework.

The accelerated occupation of land for construction has become one of the most serious environmental problems in Andalusia. Sealing the soil prevents it from conserving its biological productivity and its edaphic and climatic functions, as well as its properties in relation to the regulation of the hydrological system. This effect is even more serious if one considers that the majority of the land on which it is built usually has a high agrological or landscape quality, so its definitive occupation means de facto squandering a natural capital of incalculable value.

The construction of low-density residential centers within single-functional systems will foreseeably cause financial difficulties for cities, beyond the income that their construction could generate in the short term, when it is necessary to maintain the built city and provide adequate services to these urbanizations. This way of producing urbanization socially segregates the population according to their family economic capacity, causing a social gap that puts at risk the coexistence that has always been a fundamental feature of our urban systems.

Urban sustainability with respect to accessibility means betting on urban planning that avoids the generation of mobility based on private transport. It means a commitment to cohesion through public transport systems (bus, metro, tram...) or alternative systems to the car such as the bicycle. But also establish a new culture of accessibility versus mobility, generating a city model that creates proximity as one of its defining characteristics.

One of the most innovative and unsustainable characteristics of the diffuse city is the intense increase in the needs for motorized mobility that has occurred in the last four decades, which causes an energy and urban environmental quality problem, apart from the fact that gas emissions accelerate global climate change.

The origin of a large part of the problems of pollution and poor environmental quality present in Andalusian urban environments are a consequence of the current urban metabolism, incapable of reducing its dependence on virgin resources and closing the materials cycle.

Environmental protection in cities has become one of the issues that most concern citizens and, consequently, has received greater attention from the competent administrations.

The European Union Directive 96/61/EC, of ​​the Council, of September 24, affects the prevention and integrated control of pollution. Reducing emissions from the main industrial activities to the atmosphere, water and soil so that a high level of protection of the environment considered as a whole is achieved, helps urban sustainability.

Biodiversity is the wealth of life forms of a territory that is generated through a historical process of genetic drift, co-evolutionary interaction, environmental change and disturbances.

In urban areas, non-urbanized territory is considered unproductive from an economic point of view, so all of it can become urbanized unless it is subject to a specific protection procedure.

The metabolic needs of the urban environment require supply networks: roads, railway lines, power lines, etc. These networks, especially roads, together with the appearance of dispersed population centers, have a significant impact on the environment in non-urbanized territory. It has been shown that the fragmentation of the natural environment by these structures, by reducing the connection between spaces and interrupting physical flows, also reduces the sizes of the populations of living beings and leads to a decrease in biodiversity due to local extinctions.

The growth of impermeable surfaces with asphalt, tiles or concrete, as a consequence of urban growth, produces the sealing of the soil. The growth of the urban area forces increasingly larger land areas to be allocated to provide services (commercial areas, educational and health centres, water and waste treatment or transport infrastructure). Soil sealing implies the local disappearance of agricultural resources and the production of food and fiber, significant changes in hydrological processes at basin scales and the loss of the most important functions of the soil as habitat and biological support, the production of biomass "Biomass (ecology)"), the genetic reserve, the capacity of the soil as a sink for greenhouse gases, the filtration and transformation of pollutants, the protection of groundwater or the interruption of trophic chains.[3]​.

Soil sealing is a drastic and practically irreversible form of occupation of the surface of the Earth's crust, since soil formation is extraordinarily slow on a human scale. When a soil surface is covered with artificial impermeable materials, the renewal of the soil atmosphere and water exchange[4]​ is drastically disrupted. Soil sealing in urban areas increases the risk of flooding and contamination of surface waters and aquifers, reduces surface transpiration and contributes to climate change at a local scale.[5]​.

In the global context of changes, cities have reemerged as strategic spaces with new territorial centrality. The proximity of people, activities and functions emerges as a space from which more appropriate responses can be offered to diversity and the new challenges that arise.

The city of the century will once again be dominated by collective relationships, although the means that will be used to verify these relationships may be very different from the traditional ones. The proximity between agents, in a small physical space and high population density, has traditionally been the differentiating fact of the city. The sustainable city will have to learn to combine and preserve the spatial proximity of people and services with the proximity through communication links resulting from applying new technologies to facilitate relationships and cooperation. The local sphere thus interacts with the global sphere and this forces us to rethink interterritorial relations, redefining both the spaces over which each sphere exercises government capabilities and the very way in which decisions are made.

The management challenges of urban systems are considerable since they must respond to a constantly changing global context and the requirements of sustainability. The effort must, therefore, be focused on the definition of more sustainable urban systems for which innovative management tools must be created and put into practice in which cooperation between cities and territories must be an essential element.

Building arises from the need to establish adequate environmental and social conditions to accommodate human activities in a given space under conditions of good habitability. Housing constitutes not only a fundamental right defined by the Spanish and Andalusian Constitution and by the Law on the Right to Housing, but also a determining factor in social organization as it is the basic element of the urban environment and, therefore, of the spatial structure of society.

The recommendations of the European Union and specifically the Leipzig Charter, are aimed at not generating new housing and creating active policies for the rehabilitation of the current housing stock. Ensuring the success of the housing rehabilitation processes also includes the following aspects:

decent and comfortable place to develop.

The rehabilitation policy of centers and neighborhoods centered on people and that uses constructive instruments only as a tool for social intervention and collective improvement is the only one that ensures the sustainability, the viability, of the social systems that live in these neighborhoods. Paradoxically, although it is only a surprise at first glance, the social identity linked to a territory and its resources is a fundamental basis for the urban system to function under parameters of physical sustainability. When we consider the space where we live as our own and know its strengths and weaknesses, it is possible to develop individual and collective behaviors that conserve natural and built capital with a long-term vision.

term. Sustainability, in a broad sense, thus becomes the greatest expression of shared common destiny.[2]​.

Europe is a largely urban society and the urban has always had a considerable imprint on the culture and way of being and ways of life of Europeans. Andalusia is no exception and its territorial model tends to organize and balance the territory by promoting processes of cooperation and cohesion, relying on these urban networks.

Territorial planning constitutes the most valuable tool to address these challenges since it provides the framework in which to inscribe urban processes, valuing them from their relationship with the rest of the territorial components and contextualizing them in a certain biophysical and cultural framework.

The accelerated occupation of land for construction has become one of the most serious environmental problems in Andalusia. Sealing the soil prevents it from conserving its biological productivity and its edaphic and climatic functions, as well as its properties in relation to the regulation of the hydrological system. This effect is even more serious if one considers that the majority of the land on which it is built usually has a high agrological or landscape quality, so its definitive occupation means de facto squandering a natural capital of incalculable value.

The construction of low-density residential centers within single-functional systems will foreseeably cause financial difficulties for cities, beyond the income that their construction could generate in the short term, when it is necessary to maintain the built city and provide adequate services to these urbanizations. This way of producing urbanization socially segregates the population according to their family economic capacity, causing a social gap that puts at risk the coexistence that has always been a fundamental feature of our urban systems.

Urban sustainability with respect to accessibility means betting on urban planning that avoids the generation of mobility based on private transport. It means a commitment to cohesion through public transport systems (bus, metro, tram...) or alternative systems to the car such as the bicycle. But also establish a new culture of accessibility versus mobility, generating a city model that creates proximity as one of its defining characteristics.

One of the most innovative and unsustainable characteristics of the diffuse city is the intense increase in the needs for motorized mobility that has occurred in the last four decades, which causes an energy and urban environmental quality problem, apart from the fact that gas emissions accelerate global climate change.

The origin of a large part of the problems of pollution and poor environmental quality present in Andalusian urban environments are a consequence of the current urban metabolism, incapable of reducing its dependence on virgin resources and closing the materials cycle.

Environmental protection in cities has become one of the issues that most concern citizens and, consequently, has received greater attention from the competent administrations.

The European Union Directive 96/61/EC, of ​​the Council, of September 24, affects the prevention and integrated control of pollution. Reducing emissions from the main industrial activities to the atmosphere, water and soil so that a high level of protection of the environment considered as a whole is achieved, helps urban sustainability.

Biodiversity is the wealth of life forms of a territory that is generated through a historical process of genetic drift, co-evolutionary interaction, environmental change and disturbances.

In urban areas, non-urbanized territory is considered unproductive from an economic point of view, so all of it can become urbanized unless it is subject to a specific protection procedure.

The metabolic needs of the urban environment require supply networks: roads, railway lines, power lines, etc. These networks, especially roads, together with the appearance of dispersed population centers, have a significant impact on the environment in non-urbanized territory. It has been shown that the fragmentation of the natural environment by these structures, by reducing the connection between spaces and interrupting physical flows, also reduces the sizes of the populations of living beings and leads to a decrease in biodiversity due to local extinctions.

The growth of impermeable surfaces with asphalt, tiles or concrete, as a consequence of urban growth, produces the sealing of the soil. The growth of the urban area forces increasingly larger land areas to be allocated to provide services (commercial areas, educational and health centres, water and waste treatment or transport infrastructure). Soil sealing implies the local disappearance of agricultural resources and the production of food and fiber, significant changes in hydrological processes at basin scales and the loss of the most important functions of the soil as habitat and biological support, the production of biomass "Biomass (ecology)"), the genetic reserve, the capacity of the soil as a sink for greenhouse gases, the filtration and transformation of pollutants, the protection of groundwater or the interruption of trophic chains.[3]​.

Soil sealing is a drastic and practically irreversible form of occupation of the surface of the Earth's crust, since soil formation is extraordinarily slow on a human scale. When a soil surface is covered with artificial impermeable materials, the renewal of the soil atmosphere and water exchange[4]​ is drastically disrupted. Soil sealing in urban areas increases the risk of flooding and contamination of surface waters and aquifers, reduces surface transpiration and contributes to climate change at a local scale.[5]​.

In the global context of changes, cities have reemerged as strategic spaces with new territorial centrality. The proximity of people, activities and functions emerges as a space from which more appropriate responses can be offered to diversity and the new challenges that arise.

The city of the century will once again be dominated by collective relationships, although the means that will be used to verify these relationships may be very different from the traditional ones. The proximity between agents, in a small physical space and high population density, has traditionally been the differentiating fact of the city. The sustainable city will have to learn to combine and preserve the spatial proximity of people and services with the proximity through communication links resulting from applying new technologies to facilitate relationships and cooperation. The local sphere thus interacts with the global sphere and this forces us to rethink interterritorial relations, redefining both the spaces over which each sphere exercises government capabilities and the very way in which decisions are made.

The management challenges of urban systems are considerable since they must respond to a constantly changing global context and the requirements of sustainability. The effort must, therefore, be focused on the definition of more sustainable urban systems for which innovative management tools must be created and put into practice in which cooperation between cities and territories must be an essential element.