The Case for Efficient Lighting

The arguments for efficient solid state lighting are strong as was the interest in LED lighting demonstrated at this years Lightfair trade show.  I find however that there is a good deal of misunderstanding of the manner in which the market for efficient lighting will evolve.  Some of this confusion stems from perceptions about the phase out of the venerable incandescent light bulb.  To add to the confusion, some industry writers present a muddled view of the development of the efficient lighting industry.

In a recent article in EE Times (Ready to bid incandescent bulb goodbye?) the author makes several statements concerning the phase out of incandescents and the deployment of fluorescent and light emitting diode (LED) based solid state lighting that confuse several issues.  First, the author states that “…the argument against incandescents has some technical weaknesses.”  The author’s arguments that follow do not constitute a sound technical comparison of lighting technologies.  The compelling argument against incandescents is simply that they are not nearly as efficient at converting electrical energy into visible light as are both fluorescent and LED lamps.

The article goes on to say “…the so-called waste heat of the incandescent is not actually wasted, but serves to help keep a cool area warm.”  In already warm interior environments the heat delivered by incandescent lighting is often removed through refrigeration (air conditioning) resulting in further energy consumption.  In general, using incandescent lighting as a heating device is not a satisfactory or energy efficient heating solution.

The reason for the widespread acceptance of incandescent lighting has been that incandescent lamps are inexpensive to manufacture and provide lighting that people find attractive.  As many bodies around the world have decided, the eventual elimination of incandescent lighting is one of the low hanging fruit in our efforts to reduce energy consumption and related carbon emissions.

In one section of particularly poorly researched text the author asks: “What about the use of incandescent bulbs in extremely hot or cool consumer applications, such as freezers, ovens and dryers? You can get a temperature-ruggedized incandescent bulb for just a little more than a standard bulb, but I don’t see electronic blubs (sic) (neither fluorescents nor LED) being viable for those situations coming soon.”

This point of the article could not be less well informed.  While oven and dryer lights are not opportunities for saving a great deal of energy, refrigerated cases in grocery stores have utilized fluorescent lighting in preference to incandescent lighting for many years. Since fluorescents are more energy efficient than incandescents they throw off less heat thus requiring less case refrigeration resulting in lower energy costs.  However, fluorescent lamps become less efficient at lower temperatures while LED lamps become more efficient as their temperature falls.  This fact and reduced maintenance costs from longer lived LED lighting have resulted in the recent and fairly widespread adoption of LED lighting for refrigerated cases leading to considerable savings in energy consumption and operating costs.

The article goes on to state “The disposal and recycling of incandescents is pretty straightforward; that’s not so for electronic bulbs.”  This generalization of the properties of “electronic bulbs” is also misleading.  By not calling attention to the individual characteristics of incandescent, fluorescent and LED lamps the article misleads the reader.  While fluorescent lamps contain small amounts of mercury and when disposed of in a landfill will release some mercury, LED lamps are free of mercury.

The article attempts to sum up by stating: “Finally, electronic bulbs–especially fluorescents–require a lot of resources to manufacture, and have a long and complex BOM: ICs, passive components, PCB, packaging, and more. It’s easy but misleading to ignore that reality or pretend it is not a factor to consider in total environmental cost.”

The author of the article would better serve his audience if he reported on data such as the recent comprehensive life cycle assessment (LCA) of incandescent, compact fluorescent (CFL) and LED lamps performed by lighting manufacturer Osram (PDF file)and summarized here.

The Osram LCA takes into account all phases of the raw material, manufacturing, operating, disposal and recycling aspects of the three forms of lighting and provides useful insight into the state of lighting technologies today.  The Osram LCA of the three lamp types concludes that LED and CFL lamps are comparable today in their overall environmental impact, and that both CFLs and LEDs are superior to incandescent lamps.  Osram also makes the case that LEDs have the potential for further improvements in performance (~2x) as compared to mature incandescent and CFL lamp technologies.

Incandescent lamps are today inexpensive to purchase.  However the inefficiency and short life of incandescent lamps result in higher operating costs, higher energy consumption and more environmental impact.  Fluorescent and LED solid state lighting today offer longer life and lower energy consumption than incandescents.  As the price of LED lighting falls and the efficiency of LED lamps increases, solid state lighting will become the preferred lighting technology.  The lighting market evolution will see the phase out of incandescent lamps, and replacement of incandescents with more efficient fluorescent and LED lamps.  As LED lighting design and manufacturing develop and LED lighting competes successfully on price and efficiency, LED lighting will eventually displace fluorescents leading to still lower energy consumption and less environmental pollution.

About Phillip Wright