Protezioni solari a geometria 3D: Caratterizzazione delle proprietà ottico-radiative e verifica dell’efficacia energetica per esposizione

The control of solar gains through transparent surfaces is the primary objective in order to reduce buildings’ cooling energy needs. Heat and luminous fluxes cannot be modulated only by single glazing; thus, the transparent surfaces are protected by an external shading element with different efficacy grades, in function of the material consistency, morphology, and handling typology. In steel and glass architectures, whose design is often experimental, there is a more and more frequent use of elements characterized by a threedimensional matrix and a multi-directional performances, as for instance expanded metal or perforated metal sheets, micro and geosynthetic fabrics. The objective of this contribution is to determine, for several typologies of materials with 3D matrix, the optical-energetic behaviour and the correlation between geometry variation and performance, as a function of the angle of incidence of solar radiation. We selected 3 samples, and we measured their solar transmittance for angles of incidence from near normal to 60°. Then with numerical simulation we compared their performance and shading efficacy. The analysis carried out shows that solar transmittance does not always decrease with increasing angle of incidence. For the selected samples, the relative positioning of the texture (horizontal or vertical) affects the transmittance values: for angles smaller than 30° the samples orientation involves a performance variation up to 18%, over 30 ° this variation increases up to 43% for 60 °