From Philips page describing the L Prize:
"The L Prize® is the first U.S. government-sponsored technology competition challenging lighting manufacturers to push the limits of energy efficiency and develop a high quality solid state lighting product to replace the common incandescent bulb.
Spurred by the Energy Independence and Security Act (EISA) of 2007, the U.S. Department of Energy (DOE) established the L Prize competition to replace today’s most widely used and inefficient technology—the 60W incandescent bulb.
The competition requirements included a rigorous evaluation process for performance which included testing conducted by independent laboratories and field assessments in collaboration with utilities and other partners, to validate the performance, quality and energy efficiency of the winning product."
The Philips L Prize LED bulb is one of the most efficient (lumens/watt) LED lamps on the market.
With all that said, keep in mind there is another very similar LED made by Philips that doesn't quite have the same performance as the L Prize LED is a bit cheaper called the Philips AmbientLED.
