Would it be possible to give direction to cold air flows from forests to cool cities? A pioneering project to create cold air corridors in a Swiss forest was carried out last summer. Four 30 to 100 metres long and 20 to 30 metres wide corridors were created during a regeneration cut in a mixed forest. Although they have similar proportions, no two are identical. These corridors lead directly to the Kehl retirement home on the outskirts of Baden. The aim of the « Kühlwald » (cool forest) project is to determine whether it is possible to give direction to cold air flows from a forest to cool a built-up area, and which of the four corridors offers the best results.
At night, the forests produce these air flows by evaporating moisture. This process begins at nightfall and reaches its maximum effect at 4am. As the cool air is heavier than the warm air, it flows down the hill. Most of Baden’s forest is located on ridges, so on hot summer nights, cold air flows down towards the houses, which are in the heat of the city.
A total of 22 temperature sensors were installed in 2023, before the summer felling, at various locations in the forest, on the edge of the forest and in the old people’s home. The measurement phase of the project will last 2 years. It will be decided next winter whether this pioneering project in the Baden State Forest will open new opportunities for the future.