Thanks, Jérôme!I thought the picture was self-explaining.
As a translation:
- blue is the wind
- "toît en tôle" is the metal roof. They chose a round roof to minimize wind forces
- the actual invention is the dark grey part, made of reinforced concrete. It protects the side of the roof from the wind while letting the water gets through. In that design, that part is reinforced (it must be as it will still receive the wind efforts).