My building system is wood louver. First, let me introduce my project. My project is library with multiple store. So my project need more light than other building. But, I want to maintain my mass shape. Louver can solve this problem. Louver acts as a light-passer, but does not seriously damage the shape of the building. Rather, it creates interesting shapes of shadows and creates interesting spaces and façade. It also optionally transmits light to accept only a moderate amount of light.