Cities are increasingly experiencing episodes of high temperatures that are particularly intense in summer, and higher than in the countryside. This creates what are known as urban heat islands.
The causes? Global warming, dense population, the impermeabilization of city surfaces and the lack of vegetation
What are the risks around urban heat islands?
High temperatures can have serious consequences for the environment (increased air pollution, higher energy consumption, etc.) but also for everyone's health (dehydration, sunstroke, fatigue, headaches, etc.). These effects can be particularly serious for the frail.
We must adapt and act on the temperatures of urban spaces and the ground which absorb heat during the day and release it in the evening, preventing cities from cooling down.
Increasing green spaces allows plants to act as a solar filter and provide evapotranspiration, and developing ecological public transport that reduces anthropogenic heat are examples of solutions that allow us to act against UHI. At Veolia, we also propose to combat heat islands with water.
Use water to lower urban temperatures
Veolia’s solutions lower ground temperature by 10 to 15 °C and air temperature by 5 to 8 °C.
- Automatic roadway humidification: more suitable for drivable areas, this solution consists of spraying the roadways and sidewalks with water using a system of spray nozzles at ground level.
- Evaporative paving stones: suitable for pedestrian areas, in the event of high temperatures, this system injects water under the paving stones, using a drip system, cooling the surface through the water’s progressive evaporation by capillary action.
When possible, these solutions use rainwater stored and pre-treated for this type of use through pollution removal gullies developed by Veolia.
We offer personalized support to cities. This includes carrying out a field diagnosis as well as a technical and financial feasibility study, the implementation of suitable solutions and the monitoring and measurement of thermal comfort.
What are the benefits for you as a city?
We dit it!
Since the summer of 2018, residents of the Toulouse Montaudran Aerospace district have been able to enjoy the benefits of ceramic-based evaporative paving stones laid on a 150 m2 pedestrian zone. A rainwater recovery and storage system supplies water to the installation.
In 2019, we installed two urban cooling solutions in the Grand Arénas district of Nice: 600 m2 of evaporative paving stones made from natural scallop waste developed by the École supérieure d'ingénieurs des travaux de la construction in Caen (France) and 300 m2 of pavement humidification, all connected to the city's raw water distribution network.
In summer 2020, we installed 120 m2 of refreshing scallop waste paving stones in the courtyard of the Sousa-Mendès school in Bordeaux. A rainwater recovery and storage system is used to supply water to the installation.