Cooling with trees on the squares of Carrés Saint‑Louis in Versailles

The three squares of Carrés Saint‑Louis in Versailles have been redesigned while preserving their historical character, with trees playing a central role. By applying underground tree pits, trees are given more space to grow healthily, despite intensive use and extensive paving. As a result, the squares now contribute to cooling, quality of stay and a future-proof urban environment.

In Versailles, the historic city just west of Paris, lie the Carrés Saint-Louis: four small squares in the historic Saint-Louis district. The squares border Rue Royale and Rue d’Anjou. This project concerns Carré à l’Avoine, Carré à la Terre and Carré à la Fontaine. They are places with a distinct character, where daily neighbourhood life comes together with the monumental history of the city. The redesign had to preserve that quality, while making the squares more resilient to heat, intensive use and the demands of a future-proof public space.

Before the redesign, the trees on the squares had limited space. Paving, parking and intensive use put pressure on the tree pits. As a result, trees struggled to develop healthily and there was a risk of damage to paving and underground infrastructure. At the same time, the historical context required careful consideration: the original layout of the tree rows had to match the character of the Carrés Saint-Louis. For Carré à l’Avoine, a compromise was also sought between the desired double row of trees and the preservation of parking spaces.

During the project, existing trees were preserved wherever possible and new trees were given improved tree pits. New trees were planted in the innovative TreeParker soil cell system. This is an underground system that helps trees grow beneath paving. It provides root space, water, oxygen, anchoring and a suitable soil composition, without requiring paving, parking or other infrastructure to be removed. The system also directs root growth downwards in a controlled manner with Tree Root Guiding, reducing the risk of root heave and damage to the paving.

This historic location has thus been given a new green foundation without losing its urban function. The intervention improves the quality of stay, cooling and future resilience of the squares, while giving trees a better chance to grow into healthy, mature specimens. In doing so, Versailles demonstrates how heritage, daily use and climate-resilient urban greening can come together in one carefully designed public space.