Esser. At Échirolles, a thermal island is transformed into a green space

The problem of global warming, which has worsened in recent years, affects particularly certain regions. The Alps are therefore very exposed. Local authorities must adapt to this thriving phenomenon, the high temperature in the summer with its disastrous consequences, especially for health. Referred to as urban heat islands. The city of Échirolles, as part of the National Climate Change Adaptation Plan, has carried out a vast operation on its territory to reverse the trend by transforming an urban heat island into a local cold island. This project received the Life Artisan Award for Climate Change Adaptation, underlining its exemplary nature on this record.

Dewatering from the area

A look back at a massive two-year project. In the western sector, a major heat island has been discovered as one of the hottest in the city: it has an area of ​​8,300 square meters and consists of the courtyard of the Marcel David School and its perimeter (sports field, around the gym). In the end, a very metallic space, dark and bituminous materials, but also, all around, windswept high-rise buildings. Concretely, we could have +3.5°C compared to the average observed in the city. High summer temperatures during the day did not fall below 25 ° C at night (corresponding to tropical nights, which are very stressful for the body).

The city decided to take action with the goal of removing waterproofing from this area by moving from 97% to 27% waterproofing. The removed bitumen has been replaced by a permeable material that can drain and capture water, which also creates an evapo-transpiration phenomenon that cools the air. Concrete, which is still a bit present, makes it possible to ensure the movement of people with limited mobility and access to technical machinery. The vegetation was then greatly re-vegetated (90 trees versus about thirty trees before, but also shrubs and grass).

Rainwater is a strong component of this project with very specific management: all water collected is separated from external networks and managed on site. It provides a teaching pond as well as an underground reservoir, eventually allowing irrigation of the planting and gardening areas. A valley has also been created along the footpath. This project has also made it possible to raise the awareness of different audiences in the neighborhood about the challenges of global warming. Its production also provides essential support for educational actions, particularly in relation to biodiversity.