Piazza Cortevecchia

A Tree-Lined Square – Another challenge of the project is making the square a green oasis capable of implementing and realizing specific ecosystem benefits. The project holds that the most effective and economical measure to improve climate comfort conditions is the introduction of trees and extraordinary ecosystem tools to intervene against the urban heat island, water run-off, and air pollution. The entire project, therefore, takes place in implementing the essential idea of ​​a tree-lined square, in which the trees become the great protagonists of the public space, with their foliage, their shade, and their architecture, transforming the square into a green oasis.

The Trees – It is the liquid shade of the Plane tree (Platanus Platanor® ‘Vallis Clausa’) that was identified as the essential ingredient to structure the square as a green oasis. The Plane tree is an imposing tree, of the first magnitude, with a rounded and expanded shape, and is rather fast growing. It is a species that adapts to all terrains, prefers a position in full light and tolerates heat and drought, which also guarantees high absorption of CO2 (>2000kg CO2 in 30 years), high absorption of gaseous pollutants (O3, NO2, SO2) and high PM10 capturing capacity. In the layout scheme of the new trees, in the search for uniformly distributed shade, the identification of green islands is proposed of densely vegetated points, structured through the articulation of several trees placed side by side and intended to contribute – a typical characteristic of the Plane tree – to a “single crown” effect.

The Ground – The presence of underground utilities, foundations of ancient buildings and archaeological remains makes it necessary to plant trees at higher levels than the current walking surface, in order to reduce the depth of the excavations as much as possible. Thus, to make room for the new trees, the continuous stone ground of the square is rippled, acquiring three-dimensionality and determining the formation of specific atolls available to plant communities. The green islands are truncated cones, which emerge from the ground in material continuity with it, of variable diameter and a maximum height of one metre above the walking surface, with a section that softly connects to the level of the square, accompanying and containing the development of the root system of the trees.

The laying of the porphyry cubes also follows the specific topography created: setting a rich geometric design of concentric circles. The choice of porphyry, in addition to setting an evident material continuity with the main historic urban spaces of the city, is also motivated by the possibility of making the sealing of the joints drainable and, therefore, the paving itself.

The Underground – The project goes deeper than the pavement and the bedding layers, imagining an equally crucial “underground square”, which defines a highly innovative underground space that transforms rainwater from a potential problem to a precious resource. The project in fact includes the insertion of a rainwater collection layer, Permavoid System: which, like a sort of large sponge, collects and conserves rainwater, to return it, through natural capillary mechanisms activated by the roots – passive capillary irrigation – to the soil where the trees are planted, without using energy, pumps or valves. With this system it is possible to collect rainwater, avoiding an overload of the sewer system in the event of intense weather events, and to conserve it so that it can be used in prolonged periods of drought.

Text provided by the architect.