PFI-TT: Smart windows for on-demand control of solar heat and daylight

University Of Texas At Austin, Austin TX

Investigators

Abstract

The broader impact/commercial potential of this Partnerships for Innovation - Technology Translation (PFI-TT) project is to revolutionize building windows and automotive glass by making them “smart” and able to control heat and daylighting on-demand. Natural lighting improves well-being and can reduce energy consumption for artificial lighting. The glass under development will darken its tint when needed to avoid uncomfortable glare while maintaining the view. Sunlight also brings energy in the form of heat into buildings and cars, especially through sunroofs. While solar heating can improve energy performance on cold days, the smart glass under development can also block unwanted heating to reduce energy required for air conditioning. To achieve significant gains in energy efficiency, the smart glass technology must be broadly deployed, which requires manufacturing at low-cost. Scalable, low-cost processing will be achieved by coating the active materials from inks over large areas of glass or plastic. By controlling both light and heat, and enabling low-cost manufacturing, the project will reshape the functionality and performance of windows by enhancing comfort and reducing unnecessary energy consumption. The proposed project will address performance limitations of existing smart windows by separately controlling solar heat gain and daylighting on demand with a low-voltage controller. The project will further enable a dramatic reduction in manufacturing cost of smart windows by allowing solution-based coatings with no high energy processing steps. Nanocrystals of niobium oxide will be coated onto glass and plastic films to develop and validate the performance of rigid and flexible electrochromic devices. These prototypes will demonstrate feasibility for building skylights and windows, and automotive glass applications to improve energy performance and comfort. To overcome barriers to technology development and deployment, the project team will develop a polymer electrolyte formulation that provides sufficient mechanical stability during bending to avoid electrical short circuits while also maintaining rapid optical switching and on-off cycling stability. Transparent conducting substrates will be selected and validated that support uniform coloration during switching, allow access to a high infrared transmissive state, and remain well-conducting during film processing and device assembly. The environmental stability of the prototypes to UV exposure and thermal cycling will be established. By reaching performance and stability milestones, the project will enable realization of the commercial potential of this dual-band smart window technology. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.