Sunshade cladding unit comprising a plurality of lamellae each having a substantially flat and elongated conformation along a respective development axis, and a structure (220,220') supporting the lamellae configured to support the plurality of lamellae in a condition of parallel and spaced apart lamellae along a direction orthogonal to the development axes, the structure (220,220') supporting the lamellae being configured to support the plurality of lamellae in a rotatable manner about a rotation axis parallel to or coincident with its development axis, each lamella of the plurality of lamellae including at least one surface portion which comprises at least - a reflective layer having at least one reflective surface, and - a chromatic diffusion layer having a first surface proximal to the reflective surface and a second surface, opposite and substantially parallel to the first, configured to be illuminated by incident light, characterized in that the chromatic diffusion layer comprises a nano-pillar or nano-pore structure in a first material having a first refractive index, immersed in a second material having a second refractive index other than the first, in which the first and second materials are substantially non-absorbing or transparent to electromagnetic radiations with wavelength comprised in the visible spectrum, wherein the ratio ( n M / n m) between a higher refractive index ( n M) and a lower refractive index ( n m) chosen between the first and the second refractive indexes is comprised between 1.05 and 3, wherein the nano-pillars or nano-pores locally have a development along a main direction not parallel to the first surface and to the second surface of the chromatic diffusion layer, and the nano-pillar or nano-pore structure is characterized by a plurality of geometric parameters comprising a pillar diameter or pore diameter ( d p), a pillar length or pore length ( l p) along said non-parallel direction, a surface density of nano-pillars or nano-pores ( D p) and a porosity ( P p) of structure (30,70), and wherein the plurality of geometric parameters is configured to provide a higher regular reflectance for wavelengths of the incident light comprised in the range of red with respect to wavelengths of the incident light comprised in the range of blue and a higher diffuse reflectance for wavelengths of the incident light comprised in the range of blue with respect to wavelengths of the incident light comprised in the range of red. - a reflective layer having at least one reflective surface, and - a chromatic diffusion layer having a first surface proximal to the reflective surface and a second surface, opposite and substantially parallel to the first, configured to be illuminated by incident light, characterized in that the chromatic diffusion layer comprises a nano-pillar or nano-pore structure in a first material having a first refractive index, immersed in a second material having a second refractive index other than the first, in which the first and second materials are substantially non-absorbing or transparent to electromagnetic radiations with wavelength comprised in the visible spectrum, wherein the ratio ( n M / n m) between a higher refractive index ( n M) and a lower refractive index ( n m) chosen between the first and the second refractive indexes is comprised between 1.05 and 3, wherein the nano-pillars or nano-pores locally have a development along a main direction not parallel to the first surface and to the second surface of the chromatic diffusion layer, and the nano-pillar or nano-pore structure is characterized by a plurality of geometric parameters comprising a pillar diameter or pore diameter ( d p), a pillar length or pore length ( l p) along said non-parallel direction, a surface density of nano-pillars or nano-pores ( D p) and a porosity ( P p) of structure (30,70), and wherein the plurality of geometric parameters is configured to provide a higher regular reflectance for wavelengths of the incident light comprised in the range of red with respect to wavelengths of the incident light comprised in the range of blue and a higher diffuse reflectance for wavelengths of the incident light comprised in the range of blue with respect to wavelengths of the incident light comprised in the range of red.