This PFI: AIR Technology Translation project focuses on translating the remarkable tunability of the abruptly discontinuous metal-insulator transitions of binary and ternary vanadium oxides discovered upon scaling to finite size and upon incorporation of substitutional/intercalative dopants to fill a critical technology gap in their deployment as dynamic glazing components of thermally switchable fenestration (doors, windows, and glazed skylights). The translated smart window technology has the following unique features: thermally switchable heat-blocking properties without a significant change in visible light transmittance, tunability of the switching temperature to meet the needs of different geographic climates, and voltage-driven induction of heat-blocking properties that provides exemplary savings in air-conditioning costs while allowing natural daylight to be used to light interiors of buildings when compared to the leading competing electrochromic and static metallic coatings in this market space.
The project accomplishes this goal by enabling investigation of scale-up of the synthesis of vanadium oxides, identification of optimal coating deposition methods, and allowing correlation curves and data tables to be compiled relating critical performance metrics to coating thickness and density resulting in a prototype energy efficient window.
The partnership engages a leading manufacturer of home windows, the Technology Accelerator Fund, and the Office of Science, Technology Transfer, and Economic Outreach at the University at Buffalo to provide guidance in the fenestration industry and other aspects such as market adoption, commercialization, and insulating glass unit design as they pertain to the potential to translate the smart window technology along a path that may result in a competitive commercial reality.
The potential economic impact is expected to be ca. $118 Million in the next 4 years, which will contribute to the U.S. competitiveness in this area of green building materials and energy efficient buildings. The societal impact, long term, will be more energy efficient (even zero emission) buildings with a reduced carbon footprint and energy savings that have been estimated by some accounts to be as much as 1.0 quadrillion BTUs.
Buildings consume an inordinately large amount of energy across the world and are often static structures that interact little with their outside environments. The United Nations estimates that almost 30-40% of all energy in the world is used within buildings. The energy consumption of buildings can largely be blamed upon cooling, heating, and lighting required to render the structures habitable. A major portion of solar radiation is transmitted directly to building interiors through their windows. During summer months and in warm climates, this solar heat gain necessitates increased use of air-conditioning, straining the electrical grid and increasing a building’s carbon footprint. The increasing use of air-conditioning across the world is a critical problem that threatens to sap scarce energy resources and tremendously increase generation of greenhouse emissions. In our NSF-funded effort, we have attempted to develop thermally responsive and climate adaptive "smart window" coatings that provide energy savings by reversibly switching between two forms based on the outside temperature. Specifically, we have developed thermally and electrically switchable doped VO2 and MxV2O5 nanostructures that block heat gain at high temperatures but permit heat gain at low temperatures based on a reversible insulator—metal phase transition. In this NSF-funded research project, we worked closely with industry partners to (a) develop a method to prepare vanadium oxide nanowires that undergo dramatic and abrupt changes in their properties in response to the external temperature, (b) prepared large amounts of these "chameleon-like" phase change materials for deployment within adaptive window coatings, (c) tuned the transition temperature at which the materials undergo a phase transition in order to tailor them to different climates, (d) bonded these materials to glass to prepare viable coatings, (e) tested the coatings and found promising modulation of solar heat gain and excellent adhesion, and (f) prepared initial prototypes of double paned insulating glass units incorporating our thermally switchable glazing on the inner surface of the outer pane. The award has allowed us to bring these coatings closer towards commercial realization and has provided opportunities for training undergraduate and graduate students in an interdisciplinary environment with substantial input from industry partners.
