Bistable kinetic shades actuated with shape memory alloys: prototype development and daylight performance evaluation

Abstract

Kinetic façade systems can adjust to different environmental conditions, thereby improving daylight performance in buildings. Bistable laminates present large deflections and can maintain their state without continuous energy supply, appealing features for kinetic applications. Nevertheless, these engineered materials have yet to be studied for their potential for improving daylight performance in buildings. This study sought to test the daylight performance of a kinetic bistable screen using a case study approach that combines experimental testing and building performance simulation. This paper details research to design and fabricate the shading screen and the experimental testing of the screens’ daylight performance. First, we focus on the design of a holder mechanism, which relies on a string system and shape memory alloys that actuate bistable flaps. Second, we experimentally collect data on daylight performance and compare it to simulation data to validate a daylight model. Results show that the designed bistable screen can increase the hours of adequate daylight throughout the year versus baseline cases, particularly when oriented south and east. The study suggests that bistable kinetic screens can help improve daylight performance in buildings.