The Impact of Shading Type and Azimuth Orientation on the Daylighting in a Classroom–Focusing on Effectiveness of Façade Shading, Comparing the Results of DA and UDI

There are many kinds of façade shading designs which provide optimal indoor daylighting conditions. Thus, considering combinations of different types of façade shading systems is an essential aspect in the optimization of daylighting in the building design process. This study explores (1) how the pattern and different characteristics are evaluated by varying façade shading types and considering their impact on daylighting metrics; and (2) the relative relationships between Daylight Autonomy (DA) and Useful Daylight Illuminance (UDI) with changes of the façade shading types, input parameters, and azimuth orientations. A typical high-school classroom has been chosen as a base model, and seven different façade shading types: vertical louver, horizontal louver, eggcrate louver, overhang, vertical slat, horizontal slat, and light shelf have been applied to eight azimuth orientations for the building. As tools for parametric design and indoor lighting analysis, Design Iterate Validate Adapt (DIVA)-for-Grasshopper has been used to obtain DA and UDI for comparison. Based on the simulation, (1) the effectiveness of the installation of façade shading compared to a non-shading case; and (2) design considerations for façade shading are presented. The result shows that there are some meaningful differences in DA and UDI metrics with the variation of orientation and façade shading types, although all cases of façade shading show some degree of decrease in DA and increase in UDI values. The types of shading devices which produce a dramatic decrease in DA values are the light shelf, horizontal slats, horizontal louvers, and eggcrate louvers. On the contrary, the types of shading devices which produce a dramatic increase in UDI values are the light shelf, horizontal slats, horizontal louvers, and eggcrate louvers. In the case of the vertical and vertical slat shading, the improvements of UDI values are significant in the east and west orientations. This demonstrates that the application and design of shading devices in certain façade orientations should be carefully considered for daylight control. Also, the results show that UDI explains relatively well the daylight performance in the case of the installation of a shading device.