Nanoparticles suspended in a film manufactured by Hitachi Chemical Co. under license from Research Frontiers let users control the tint of a car's sunroof. Billed as an energy saving feature, the glass ranges from between super dark (blocking over 99.5% of visible light, which is about 50-60 times darker than a typical sunroof) to about twice as clear as an ordinary sunroof.
Within the SPD film are randomly oriented microscopic particles. When no electrical voltage is present, the particles absorb light and block it from passing through the film. With an electrical voltage applied, the particles align so light can pass. At line voltage, SPD film typically uses a maximum of approximately 0.06 W/m2. No power is used when the film is in its dark state. When operating at light transmission levels between the clear and dark states, power requirements are correspondingly lower than the maximum. Exact power consumption depends in part upon the thickness of the SPD film used for a specific end-product application and other factors.
The new Mercedes-Benz SLK will be the first large-scale series production vehicle to use Research Frontiers' patented SPD-Smart light-control technology. Test data published by Mercedes-Benz shows the ability of the roof to reduce sun exposure to 1/20th of direct exposure levels (from over 1,000 W/m2 to less than 50 W/m2). Mercedes-Benz reported that when compared to conventional automotive glass,the use of SPD-SmartGlass significantly reduces the temperature inside the vehicle by up to 18ºF/10ºC. This reduces air conditioning loads, thereby saving fuel.
The glass can be used in settings besides vehicles. SPD-SmartGlass is now being integrated into other applications including architectural windows and skylights, aircraft windows, and marine glazings. The University of Cambridge Dept. of Engineering recently published a study concluding that SPD-Smart light-control architectural windows are exceptionally energy efficient, reducing solar heat gain by as much as 90% -- and contribute to a 65% reduction in annual cooling loads. Additional benefits include greater than 99% blocking of harmful UV light.
More info: http://www.smartglass.com/