Over the past decade, high-brightness monochromatic (colored) LEDs have been replacing traditional incandescent light sources in certain niche applications such as traffic signals and “EXIT” signs. LEDs are able to save up to 80% energy and significantly reduce maintenance costs in these applications. A similar trend is expected in architectural, transportation and general illumination with white LEDs. Even though the efficiency and light output of white LEDs have been improving steadily, they still need to improve by twice as much and offer good color appearance before they achieve the target of 200 lumens per watt with high color quality, as set by the SSL industry.
Zhu, Yiting, "Optimizing the Performance of White Light-emitting Diodes for Energy-efficient Lighting" (2009). Link Foundation Energy Fellowship Reports. 3.
Link Foundation Fellowship for the years 2007-2009.