| Currently, most building envelope elements such as facades, roofs, and windows are constructed from static components and materials which are incapable of altering their optical properties. For a climatic region with seasonal variation between winter and summer, building elements that can modulate properties with respect to solar loading and desired interior conditions will improve building energy efficiency and control the solar radiant-to-building thermal transition. The ability to control the quantity of absorbed and emitted energy directly impacts heating and cooling energy consumption. This research focuses on the development of controllable optofluidic building envelope elements capable of modulating transmittance, reflectance, and absorbance.;Switchable glass or smart windows are devices capable of modulating light transmittance when voltage, light, or heat is applied. These devices allow for the state of the glass to switch from transparent to translucent, or vice versa. This transition can occur passively or actively depending upon the device technology. Primary active technologies that respond to electric stimuli include electrochromic, polymer dispersed liquid crystal, and suspended particle devices. However, these commercially available smart glasses rely on exotic materials and intricate manufacturing techniques, resulting in high cost for the end user. Furthermore, drawbacks to such devices include optical losses in thin films, continuous power draw, and poor transmittance modulation.;This dissertation demonstrates a low cost novel optofluidic device capable of modulating visible light transmittance from 8%--85%. Several studies are presented in this work including spectral performance, variable angle transmittance, cycling data, and device improvements such as optical coatings and optimized designs. Utilizing 3D printed geometric optics and the concept of refractive index matching, the optical transmission, reflection, and absorption can be tailored. The principle working mechanism of the proposed devices utilize total internal reflection between the material-air interfaces. Light incident upon a repeating pattern of corner cube reflectors reflects light back to the source (retroreflection). Filling the interstitial space with a fluid results in increased light transmittance. As the refractive index of the fluid increases to that of the surrounding material, refraction decreases, and specular transmittance increases. If an absorptive coating is applied to the backside of the device, then the absorbance can be altered resulting in an energy efficient switchable building envelope. Thus, the device presented is capable of modulating reflectance, transmittance, and absorbance and offers the optimum solution to tailoring solar loads for increased heating, ventilation, and air conditioning efficiency. Additional applications of this type of optofluidic device presented include privacy panels, dynamic camouflage, and architecture. |
