Thermo-bimetal responsive building skins: comparative analysis of self-actuated geometric patterning and user override on daylight and energy efficiency

Kinetic facades have emerged as a promising strategy for optimizing daylight and energy performance, yet there is a growing need to simplify their design and operation. Despite advancements in facade design through environmental simulations and algorithms, many contemporary kinetic facades remain complex, relying on mechanical parts that are difficult to maintain and require energy to operate. Recent research advocates for the use of “smart materials” in facade design, leveraging the intrinsic properties of materials that can change geometry in response to environmental factors like light, heat, humidity, pressure, and wind velocity (Vasquez et al., 2019; Sung, 2016).

This study investigates the use and effectiveness of temperature-responsive bimetals as an alternative to mechanically controlled kinetic facades, focusing on environmental performance, occupant override capabilities, and user satisfaction. We developed a digital workflow and VR-based simulation to visualize the real-time behavior of bimetal facade systems using climate data. The research compares the dynamic behavior of these facades against the static shading systems with the same module design but varied patterning logic, analyzing the impact on daylighting metrics, energy use intensity (EUI), and occupant overrides.

Methodologically, the study is structured into five phases: material selection, material programming, facade design, performance evaluation, and visualization through virtual reality (VR). Miami’s hot and humid climate was chosen as the study location, with simulations focused on daylight performance and energy usage. The results indicate that the dynamic behavior of the façade systems provides more uniform daylight conditions in the occupied areas when compared to a static configuration of the same design. Energy analysis revealed that while the dynamic facades improved energy performance compared to a baseline with no shading, the introduction of occupant overrides (ranging from 20% to 40%) led to a marginal increase in EUI, suggesting a small trade-off between daylighting control and energy efficiency.

This research offers a framework for evaluating thermo-bimetal shading systems in architecture, with implications for refining simulation methods, exploring different climate zones, and enhancing the integration of occupant experiences in future studies.