Bergh replies: Compact fluorescent lighting is a mature replacement technology for incandescent light, but solid-state lighting offers an entirely new lighting paradigm. John Waymouth missed a number of points in comparing SSL and compact fluorescent lamps.
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SSL lights turn on instantaneously and maintain their color when dimmed. Their color is dynamically adjustable and can be easily integrated with silicon integrated circuits to provide “smart lights.” None of these attributes is available for CFLs. In addition, CFLs have poor color rendition and a poor form factor in replacing incandescent lamps.
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CFL efficiency is around 60 lumens per watt, compared to the expected efficiency of 200 lumens per watt for SSL.
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CFLs are isotropic emitters leading to 20–50% light loss within the fixture. In contrast, the quoted LED efficiencies are measured at the output of the fixture and have no additional light distribution losses.
Proponents of the old technology tend to resist the new. However, a testimony on the promise of the new technology is reflected in the position of traditional lighting companies such as OSRAM Sylvania and General Electric Co, which have fully embraced the Next Generation Lighting Initiative, a government–industry partnership to accelerate the development of SSL.
With regard to Jerry Woodall’s letter, our article was aimed at lighting and hence at visible LEDs. Holonyak’s red emission from GaAsP alloys was an early demonstration of a visible LED.
