Green as a structure
The general structure of the park
"The image of the city, its clarity, strength and identity depends to a large extent on the system of public spaces that structures it... "
Krier, 1975
In this hypothesis of urban greenery design, trees have a structuring function, that is, they have the ability to give a design to the city by themselves, they are presented in a linear manner, they determine full or empty masses, they mark and create volumes, spaces and paths.
Both the "full" spaces of the buildings and the empty spaces of the city contribute equally to the construction of the form of the urban project: the squares, the streets, the avenues, the new spaces for socialisation, the parks, the gardens, the belvederes, the car parks, the vegetable gardens and the waterways.
The unbuilt space is entrusted with a key role in the functioning of the city, a system of environmental and natural connections that include a series of design episodes, places of “refuge” for meeting, socializing, consumption of services and use of equipment.
In this way, greenery takes on the role of an element of recomposition of the urban form, a unitary system, a green network of interconnected spaces complementary to the network of public spaces determined by the buildings.
Some text elements and ideas are taken from:
The Compact City. After Postmodernity. The New Codes of Urban Design
by Roberto Cassetti 
Shade comfort evapotranspiration mitigation
URBAN GREEN INFRASTRUCTURE
WHAT IS IT AND HOW DOES IT WORK?
Urban green infrastructure is a multi-functional network that performs various functions in the city:
ecologica, because it connects natural and semi-natural elements (parks, waterways, canals, vegetated and permeable areas), improving the environmental quality and biodiversity of the city, also with respect to the migration of animal species;
- landscape and historical-cultural, because it connects open spaces, historical and cultural assets and green areas (squares, monuments, gardens, urban parks, tree-lined streets, vegetable gardens, etc.);
- of accessibility and public use, because it safely connects recreational and work activities through pedestrian and cycle paths;
- of connection with peri-urban spaces, because it integrates the countryside with the urban environment.
The urban green infrastructure is constituted by the integration of this system of networks that all together determine the multifunctionality of the green infrastructure and its quality. The green infrastructure therefore acts more effectively under different profiles: biodiversity, resilience of the city to extreme temperatures (waves and heat island) and to heavy rain events, thermo-hygrometric comfort of people, sociability, usability and liveability of public spaces, movement...
HOW TO DESIGN AND BUILD IT?
To design and build an urban green infrastructure, it is necessary to develop the concept of physical network at different scales, first taking into account the existing invariant elements:
- natural and semi-natural, such as rivers and streams and wooded areas;
- public green spaces, such as parks and gardens and sports areas;
- rows of trees;
- gardens and orchards, public and private;
Once the invariants of the green infrastructure have been identified, it will be necessary to verify and define all the spaces and elements of the project – small or large, public or private – that can connect the parts through specific and linear elements:
- intervening on road sections, by unsealing the soil and inserting trees and vegetated spaces (trees, shrubs, rustic lawns, etc.);
- creating rain gardens (on the roadside, in squares and car parks);
- promoting the multifunctionality of green spaces (ecosystem services, sociality, shared gardens, urban gardens…);
- intervening in interstitial public spaces, resulting, and treating them with adequate plant supplies;
- providing guidance for the management of private greenery.
The ability of vegetal spaces to influence the thermal state is demonstrated by the fact that adequately connected green spaces (particularly through trees when they form a continuous vegetated network) have a thermoregulatory capacity greater than the simple sum of the capacity of each of them.
Pig iron: Regenerating the city with nature
Tools for designing public spaces between mitigation and adaptation to climate change
Valentina Dessì, Elena Farnè, Luisa Ravanello, Maria Teresa Salomoni
The author of the cover image is: elenabs on Depositphotos.com
