DOE OSTI2013
Over 4 Quads of energy are lost through windows annually. Passive coatings reduce wasted energy, but energy lost through windows would remain over 2 Quads with complete replacement of Low-E glass. Active control of transmitted light and solar heating with electrochromic (EC) windows can transform the efficiency of energy use within buildings, thereby reducing energy footprints and corresponding greenhouse emissions. High production, integration, and distribution cost limits adoption of current EC products. ITN aimed to utilize its proven heritage of efficiently transitioning technologies from rigid to flexible substrates employing roll-to-roll manufacturing to capture the emerging EC window market opportunity. The project focused on three main efforts (1) Transition Small Scale Prototypes To Limited 0.5 Meter Wide, Web Coater Production, (2) Satisfy Market Driven EC Performance Metrics on Plastic Substrates, and (3) Product Development and Commercialization. The overall goal was to substantially reduce investor risk to motivate private investment in a production facility to further transition and scale this promising technology. A 0.5 meter roll-to-roll web coater was designed, constructed, and commissioned at ITN to support EC development effort. With this tool, we were able to establish the feasibility of roll-to-roll production of EC devices. Individually layers were continuously produced at lengths up to 3 meters with good uniformity, both down web and cross web. Solid state devices were produced, and device performance was being enhanced through hardware modifications underway at the close of the project. When deployed in composite device structures, we were able to verify that individual layers were able to achieve a transmission range of 3-70% transmission average over the visible portion of the spectrum. Initial development of intelligent process controls led to verification of a 2-state controller employed during deposition of the electrochromic layer. The project also successfully increased device performance in line with market needs. Improved device materials provided increased transmission range to a 5-65% transmission over the visible spectrum and faster switching times for both small area batch parts and large area composite materials. We were able to demonstrate durable cycling over 10,000-20,000 cycles in a variety of architectures including suspended films in an IGU and films laminated to glass tested in open air representative of retrofit applications. Robust packaging techniques were identified and samples proved durable even in 40C and 100% relative humidity outside the IGU environment.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗