Design Guidelines for the Utilization of Tilted Façades to Enhance Building Energy Performance

Intense solar radiation is one of the key design problems for buildings in tropical regions. The recommended practice is to install shading devices, particularly to protect glazing systems. However, many design factors do not allow shading devices to be implemented in all cases; shading devices may not be appropriate to particular design concepts. To serve the designers' preference, alternative solutions should be provided. This study aims at investigating the performance of a new design alternative—the tilted façade. By simply tilting a wall downward, solar radiation can be minimized in the same way as a shading device. The state-of-the-art energy software, eQUEST, was used to simulate energy performance of buildings in Bangkok, Thailand. At the same time, simulated results were confirmed by using experimental data monitoring from specially customized test cells. A wide range of WWR (Window to Wall Ratio) was tested against different façade orientations, glazing types, and shading devices with similar projected lengths. Tilted façades can be most effective for all orientations except for the north. Also, tilted façades allow designers to use more glass without any additional energy consumption. Based on these results, a set of design guidelines for using tilted facades are proposed. Designers can not only utilize these guidelines to effectively adjust façade angle but also optimize the glazing size for the best energy performance.