For decades, meteorologists and climatologists around the world have been observing the effects of global warming on meteorological phenomena: more rainfall or more drought, more heat waves, more and more extreme weather events: cyclones, storms, hurricanes, etc.
It is therefore necessary to adapt. This involves protecting property and people (heatwave plan, flood plan, fight against fuel poverty...), maintaining and preserving natural heritage (forests, dunes, dikes...) or urban planning (urban and built planning; fountains and refreshment points, green spaces and vegetation...). Cities are particularly concerned by global warming due to the density of activities and populations.
Paris is the French city most affected by the Urban Heat Island (UHI) phenomenon. This phenomenon results in the creation of a heat bubble above the city that is subjected to high heat during the day. This bubble is not present in rural areas thanks to the abundance of vegetation and permeable soils that consume/absorb the solar energy received during the day instead of being, as in cities, accumulated and stored in the materials of buildings and impermeable surfaces.
Temperature differences between urban/rural areas in Paris are around 2.5°C but can reach 10°C in summer. However, within the same agglomeration, there are micro-zones of heat and "islands of coolness". These variations are due to the morphology of the city, the radiative and thermal properties of the materials and the land use pattern on a neighbourhood scale.
In this context, the FRESH-ECOPAVERS project was born between Normandy and the Seine Valley. Indeed, Normandy and more particularly the laboratory of ESITC Caen developed in 2015 a shell concrete paving stone whose formulation gives it a major draining character. This paver was initially designed to meet a local demand for shell recycling, available in large quantities on the coast. In this context, ESITC Caen's laboratory has positioned itself as a player in the circular economy by replacing gravel (an exhaustible resource) with shellfish waste (in abundance). The shell paving stone was born and its characteristics were studied. We thus noted that the presence of
shells in the concrete gave the paver an important porosity and therefore a strong draining character.
This paver is now under license and is sold throughout the metropolis. However, if it is capable of draining water quickly into the ground, the opposite effect is also possible. This paving stone would thus have the property of restoring the freshness of the soil in conditions of high heat. Thus, for functions such as parking lots, bicycle paths, waste treatment areas... a shell paver zone would allow the artificial creation of islands of coolness, so disparate on the scale of a city like Paris.
The aim of the FRESH-ECOPAVERS project is therefore to carry out pilot operations in Normandy and to complete them in the Ile de France region and to instrument them in order to study and optimize this phenomenon of islands of freshness.
The FRESH-ECOPAVERS project is a 960,000 euro project co-financed by ADEME, the Région Normandie and the Région Ile-de-France, bringing together 4 partners: ESITC Caen (project coordinator), ESITC Paris, the Agence Parisienne du Climat and the city of Alençon.