Abstract
Green areas are emerging as a vehicle for change towards more sustainable cities. Green areas include, among other facilities, parks, gardens, and urban gardens. These facilities should be designed in an inclusive and integrating way, allowing their use by anyone. Their incorporation into urban policies has many advantages: a more naturalized landscape, improving the microclimate of urban neighborhoods, biodiversity, and the health, both physical and mental, of users and neighbors. They can also serve as an instrument for the education of citizens in environmental topics, healthy eating, and ethical and social awareness, from a very early age to the elderly.
TopIntroduction: Green Areas For Sustainable Cities
Since the industrial revolution, in the second half of the 18th century, caused a massive exodus from the countryside to the city, cities have been growing, causing changes in urban planning, in the environment and in the way people interact.
The increasing size of cities makes it necessary to use both public and private transport. Distances are increasing and it is necessary to have a well-connected public transport network or private vehicles with which to attend to professional and family obligations. This has given rise to an excessively large fleet of vehicles, still today, and in most cases, powered by internal combustion engines (Otto or diesel engines). With them, pollution, noise, physical and mental illnesses that affect the population have also increased in recent decades. All these problems are associated with the excessive use of motor vehicles, among others, as numerous studies show.
According to the World Health Organization (WHO, 2022), pollution in cities causes millions of premature deaths per year worldwide (4.2 million premature deaths, according to WHO data from 2016) caused by cardiovascular and respiratory diseases, as well as by different types of cancer, among which lung cancer predominates.
This pollution is aggravated by the energy balance that cities have and by the heating that increases in them. The heat given off by asphalt in cities causes the phenomenon known as “heat island” (Simón Grau & López Ayerra, 2018). It is a phenomenon whereby the urban area appears noticeably warmer than the surrounding areas. This is mainly due to pavement, which occupies approximately 20% of the surface of cities (Correa et al., 2003). Materials such as asphalt used on streets, as well as other materials used on sidewalks and buildings (concrete, roof tiles, ceramic tiles, for example), are materials with high thermal capacity and low solar reflectance (Correa et al., 2003). This causes these surfaces to absorb and accumulate heat, causing this thermal phenomenon. The increase in temperature in cities increases the problem of air pollution, since a higher ambient temperature causes an acceleration of the reactions of the combustion gases present in the atmosphere.
Universities and research centers are studying the thermal behavior of the different materials used in civil construction. The solutions involve the use of suitable materials and increasing the surface area of green areas, also on the surfaces of buildings. The re-greening of buildings, through vertical gardens (sometimes called Green Wall or Natural Wall) and roof gardens, are currently widely considered solutions worldwide that also favor the indoor climate of the building (Timur & Karaca, 2013) and reduce the feeling of stress (Lotfi et al., 2020).
These installations, whose concept emerged thousands of years ago, require certain infrastructures (irrigation, fertigation, misting, automation) and management (pruning, plant replacement) that make them, depending on the system on which they are established and the type of plants, costly or with a certain need for maintenance. They can be installed on different systems or supports, which, depending on how they are, will facilitate maintenance more or less. They are, specially, solutions for public buildings, since in residential blocks they can result, in some cases, with an excessive maintenance cost for the community of neighbors. The climate, exposure of the wall, the price of the supporting material and plant characteristics are key factors for the success of these systems (Sarkar, 2018; Chernova et al., 2020).
Vertical gardens modify the landscape of cities, making their facades more natural. In addition, they add value to the buildings where they are installed, making them easily recognizable on an international level. In many cases they turn out to be the characteristic element, which becomes the building's trademark. This is the case of such emblematic buildings as those mentioned below:
Key Terms in this Chapter
Industrial Revolution: A period in recent history (second half of the 18th century) in which a technological transformation took place, affecting the social and economic dimensions.
Heat Islands: Very localized spaces in the cities that allow reducing the excess heat in them, as a consequence of the asphalt and the greenhouse effect caused by the exhausted gases, product of the combustion of the thermal engines of the vehicles.
Combustion Gases: Combustion products in thermal engines (CO, HC, NO x ).
Sustainable Development Goals (SDG): Goals or achievements that governments have undertaken to achieve, as social, sustainable and economic commitments. Seventeen sustainable development goals are established.
Urban Garden or Agricultural Garden: Integrated installation in the city for agricultural use. It is normally associated with a sustainable agriculture system (cultivation in the absence of chemical products) and self-consumption (its main destination is not the sale of the products).
Ecological Agriculture: Agricultural production based on respect for the environment. Agricultural products are produced in the absence of chemical products.
Urban Planning: Group of technical and political instruments that make it possible to organize the space of cities (streets and buildings) for their optimal management.
Agriculture: Technical and economic activities related to food production through the cultivation of comestible crop species.
Naturalization: Introduction of plant species in an urban or industrial context with the objective of impacting on the environment and the social context.
Rain Gardens: Landscaped areas with a sustainable drainage system that allows the infiltration of rainwater, canalizing the recovered water to a storage tank. This prevents erosion due to rainwater runoff.
Landscape: Any environment perceived by the observer as having a defined character, determined by the interaction between nature and human activity.
Roof Gardens: cultivated plants located on the rooftops of buildings. They favor the thermal insulation of buildings.
Green Areas: Urban areas with a high content of vegetal species, for recreational use. This term includes parks, gardens, urban gardens or agricultural gardens and sports fields.
Inclusive Area: Facility or area that allows its use by the public, including people at risk of exclusion, such as people with disabilities or the senior citizens.
Green Lungs: Areas with a high density of plant species that generate high amounts of O 2 due to their life cycle.
Vertical Gardens: Is the cultivation of plants on the facades of buildings using different supports and infrastructures, such as irrigation. They are also called by the names of Green Wall or Natural Wall.
Formal Education: Training that takes place within the classroom, with a previously established design through a teaching plan.
Combustion Engine: Machine invented at the end of the 18th century, from which mechanical energy is obtained from chemical energy obtained from a fuel, generating, in addition, contaminant gases such as CO, HC, NO x .
Non-Formal or Informal Education: Training that takes place outside the classroom, in an uncontrolled environment and without an established long-term teaching plan.