Investigating the influence of perforated façade skins on indoor illuminance level: a case study

Building shading systems is crucial to both avoid indoor overheating during summer and control daylight inflow. This is particularly relevant in exposed glazed façade during summer, where the risk of excessive solar radiation and light entering the building is elevated. The study proposes the use of Dialux software to support the design of sunshading devices with the two-fold objective of reducing the risk of glare along the façade side and avoiding a dark effect on the opposite side. The procedure is based on a multiple-design approach that simulates the effect of diverse shading panel configurations on indoor illuminance distribution. Then the procedure is implemented on a residential case study in Bologna (Italy) resulted in having a limited depth and thus a high risk of excessive illuminance. The results demonstrate that Dialux is sensitive to changes in the openness factor and geometry of the panel. The multiple simulations allowed the optimal illuminance level of around 300 lux for more than 70% of the case study room surface while containing the area exceeding the optimal level under 1000 lux to less than 20% and to avoid reaching the minimum threshold of 100 lux through a shading system with Openness Factor ranging between 11 and 15%. The workflow can serve not only as a tool for addressing and verifying the design choices but as a design support means itself. Due to its structure and easiness of inputting data and modelling stage, the methodology has a high replicability potential.