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The Le Ray Project in Nice: Irrigation of planters and plants at ground level

The Le Ray project was created on a 3-hectare park in Nice, with the idea that nature regains control over the buildings. The project consists of private housing, social housing, an industrial estate, a dojo (for martial arts), an associative hall and shared gardens. It is also the largest green façade project in Europe.


The Le Ray district is a neighbourhood in Nice with a strong popular identity, which also has a river and football stadium. Lou Ray is a small spring that used to irrigate the Mediterranean plants that supplied the oil mills. The area also has a sporting heritage; the Eagles (Les Aiglons) played there from 1927 until 2013, when the stadium was demolished and replaced by a new one on the Vat plain. A section of the sports complex was conserved as part of the development project: the iconic stand and a football pitch.


A wide range of plant species

This green façade project has been driven by the architect Edouard François, on a massive scale, enhanced all the more by the park. “We have established a park in the place where the Le ray stadium stood and this project falls within the scope of the park extension”, explained Edouard François.

The building consists of weatherproof wooden slatted cladding that is the hallmark of the designs of Edouard François. The wooden slats have been modified slightly here, being made of Robinia wood, a very durable European timber of excellent quality that comes from certified European forests.

According to Jean-Frédéric Gay, landscape architect: “We had to return the site to nature”. The park has three types of pines grown here:  Aleppo Pines, Maritime Pines and Italian Stone Pines. Then, with the influence of Edouard François and the building project, they found it worthwhile to add a little more diversity.

Jean-Frédéric Gay added: “We have tried to maintain the spirit of the Riviera, from Nice to Menton, and the region’s climate, in particular, has enabled us to introduce plants from all over the world”. And he continues: “We have two main features here: the natural area consisting of pine trees and scrubland, which is situated in the park.  And inside the project we have planted a special form of vegetation, a very lush garden of the Riviera type”.

In the areas around the buildings, firstly, to prevent the pavements actually touching the façades, we laid strips of earth; pines, shrubs and perennials were then planted there on the open ground.

To cover the walls with vegetation we had to use climbing plants, so you will find jasmine, rose bushes and honeysuckle. The green facades are a special feature, the result of new research developed by Edouard François: the anastomosis or physical/functional fusion of the organs (branches or trunks) of two plants. He explains: “We have pots with climbing plants placed in them and then they are all grafted to each other. Botanically, after three years, there will be one single and unique species”.

And pine trees were planted on the roof-terraces, using dwarf species so that they can form a green roof, thus blending in with the park.

Finally, the two central buildings have a shared garden on the roofs, with the market gardening activities managed by a professional association. The local residents will be able to take part in the gardening and harvest the fruits of their labours.


The irrigation system

All the planted areas are watered. The irrigation system was designed by Florent Poissonnet, from JFL Concept [main irrigation contractor]. At the intake, there is a general supply for the whole project, which is then separated into: one supply for the co-ownership scheme (condominium) and one supply for the municipality.

Irrigating the buildings. The co-owned section is supplied by a pumping station, which links up with a 150 m3-capacity replenishment reservoir, fed by the rainwater in the basement at level -2 (60% of the rainwater is directed into the tank).  A device allows for the tank to be supplied with potable (mains) water when there is insufficient rainwater stored. The distribution point is located in the basement -2 in a special service room for the irrigation system, with a pumping station, self-cleaning filter and dosing pump for applying inputs and nutrients. There are four outlets in the service room allowing for the irrigation water to be distributed to the co-owned section: two for supplying the areas at ground level and two for supplying the irrigation water to be distributed to the buildings (façades and roofs). The two systems that supply the buildings are in the basement -1 allowing for a loop to be formed that allows the system to be supplied with water for each building.

In the middle of the eight buildings, an outlet supplies each of the buildings and a water meter allows for each building to be managed individually.

In each building, the water supply and electrical equipment, located at levels 1, 3,  5  or 7 and allowing for 2 or 3 levels to be supplied at the same time.  The distribution to the roof is achieved with equipment situated on the last floor, i.e., service ducts with water supply pipes. There are associated outlets leading from the service ducts, which can be connected to the façades of the buildings.

There are three models of planters (or plant pots): two rectangular models and one square model (1 x 1 m), planted with pines and embedded in the façade or on the terraces. The plant pots are irrigated with Netafim’s anti-syphon Unitechline microirrigation drip lines. The same applies to the large  plant pots (2 x 1 m) on the roofs. In some pots, depending on their exposure, supplementary Techflow drippers have been added to the drip system (4 or 5 per pot). The flow rates are variable and they can be adjusted according to the type of plant and level of exposure. This also allows for the growth rate of the plants to be controlled.

The installation is equipped with 30 solenoid valves for all the buildings and 15 solenoid valves for irrigating the areas at garden or ground level. The company CGME is responsible for the irrigation work.

Irrigation of the surrounding areas (irrigation by the municipality). The irrigation of the surrounding areas is the specific responsibility of the municipality and the system is supplied from the city’s untreated water network.

A distribution network allows for all the surrounding areas (South, North, East) to be supplied. The general connection is of DN50 – and 15 solenoid valves allow for the management of the secondary networks. The whole area is irrigated with Netafim’s Unitechline subsurface drip irrigation system.

Programming.  The project has two Hunter decoder-type controllers (ACC2):

- One for the co-owned section,  located in the service room in the basement at - 2 level

- One for the municipality located in the control box at garden at ground level)

Maintenance. The irrigation installation for the surrounding areas will be managed by the municipality and the irrigation system for the co-owned section will be controlled by an individual private firm.

According to Jean-Frédéric Gay, “It will be even better in 5 years’ time.  In three years we will have full cover and in 5 years the project will have reached its zenith”.



Growing plants and making the city greener helps to reduce the effect of the phenomenon suffered by all city dwellers, the urban heat island effect. The aim is also to offer the residents sensual experiences of colour, nature and texture in the city and develop the biodiversity. The park is home to bats, swallows and lizards. Bird houses have been reinstated. The plants have also been chosen for their colours, which attract insects and butterflies.