Assessment of angular visual transmittance of Perforated Masonry Walls patterns employed as solar shading systems

Perforated Masonry Walls are traditional construction systems typical of the Mediterranean area, especially in existing rural buildings. Practical reasons are linked to their original employment as a separation element meant to be air permeable to promote cross-ventilation. Successively, they started to be designed for achieving architectural goals, integrating them with additional internal glazing. Moreover, due to their geometry, they can behave like real solar radiation shades, permitting daylight influx while controlling solar penetration. The implication of the use of these systems on daylighting and energy fields have not been widely analysed. This research intends to establish a starting point for their detailed daylighting analyses, considering them as Complex Fenestration Systems. To do so, brick materials were characterized through direct measurements of visual reflectance on a heterogeneous group of brick samples. Results show that reflectance values fall within the range of 0.081–0.262. Angle-dependent transmittances of seven masonry patterns were produced using Bidirectional Scattering Distribution Functions (BSDF) calculated with Radiance. For which, the highest reduction in visual transmittance values was found for solar incidence angles greater than 45°, reaching peaks approximately at 55–65°. These were tested and compared as shading systems on a test room with a South oriented glazed façade, located in Milan. Their implementation resulted in a mean indoor illuminance decay of ~15%. Lastly, the perforation ratio was confirmed not adequate to provide an insight into the visual performance of shading devices.