Light bulbs haven't been sexy tech since Thomas Edison's day, but innovation has come to an industry that has seen relatively little of it for a century. Today, the lighting industry is in a remarkable state of flux, and much of it has been driven by government action.
Over the last half-decade, a gradual shift toward more energy-efficient light sources has gathered momentum as nation after nation legislates against the sale of incandescent light bulbs. Venezuela and Brazil started the trend in 2005. Australia and the European Union began phasing out tungsten lightbulbs in 2009. Argentina, Russia, Canada, Malaysia and the United States will have joined the throng by 2014, either by phasing out incandescents outright or (as in the US) by setting minimum efficiency requirements which in effect prohibit most incandescent light bulbs.
With recent data published by the Earth Systems Research Laboratory putting global atmospheric carbon dioxide levels higher than ever, such legislation is certainly timely. Consider the tremendous impact of electric lighting: Department of Energy figures cite electric lighting as responsible for 11 percent of residential and 25 percent of commercial energy consumption in the US. That`s all energy, not solely electricity.
This is the story of the four main heirs to the incandescent throne—linear fluorescent, compact fluorescent, LED, and OLED—and of the future tech that may one day dethrone these upstarts. From pocket calculators to living room lamps.
The story of the last decade of electric lighting is dominated by the rise of the light-emitting diode (LED). LEDs are members of a new family of solid-state lighting technologies that eschew traditional means of illumination, such as electric filaments or plasma discharge, in favor of electronics. Simply put, LEDs are semi-conductor devices which, when transmitting electrical current, corral electrons into lower energy levels, emitting photons in the process.
LEDs began their commercial life at the outset of the 1970s as humble indicator devices, used in simple displays like the lava-red seven-segment display of Hewlett-Packard`s first pocket calculator, the HP-35. Today, LEDs are the diminutive powerhouses of lighting. Commercially available units have broken the killer 100 lumens per Watt (lm/W) luminous efficacy barrier (the "lumen" is the standard unit of luminous flux—useful light output—while "efficacy" is the ratio of light output to power and measures the efficiency of the bulb).
The exponential increase in LED efficacy was identified in 2000 by Dr. Roland Haitz. The Haitz Law, loosely analogous to Moore`s Law, predicts a doubling of LED lumen output every three years, with cost dropping by a factor of ten every decade. That year, Haitz predicted that the 100 lm/W benchmark would be broken in 2010. He was right. Rocketing efficacy has allowed LEDs to conquer niche after market niche, from the bicycle headlight to the traffic light, from the emergency light to the desk lamp.
But LEDs have more to recommend them than mere efficacy. Manufacturers` claimed lifespans routinely exceed 50,000 hours—that`s the better part of six years continuous illumination. They can now can be had in a range of colors, including cyans, magentas, ambers, cool whites, and (recently) warm whites, which was a crucial development LEDs needed to mount a serious challenge in home and office lighting.
High upfront prices have kept LEDs out of many homes, but prices are dropping, and manufacturers believe that LEDs has a bright future in the home. Peter Soares, Director of Consumer Channel Marketing at Philips Lighting, told Ars, "As prices come down, LEDs will be able to replace the more powerful incandescents. It`s more a rugged technology, it doesn`t have glass or a fragile filament inside, and doesn`t have any mercury to worry about at the end of its life. LED will certainly be the long-term winner in the home."
They are also close to taking on exterior lighting. Gas-discharge lamps (particularly metal halide and high pressure sodium lamps) were traditionally the first choice for decorative illumination of building exteriors. These high-powered pieces of kit, sometimes rated at more than a kilowatt each, are effectively light canons, illuminating entire building façades from the ground. It`s a brute-force approach to lighting in defiance of the inverse square law, necessitated by the heft of the lamps and the need to get at them for maintenance.
LEDs provide a lower-energy alternative to gas-discharge, but it's not because they`re is more efficient (they're not, yet—high pressure sodium lamps reach 150 lm/W). But LEDs can save energy because their size and long life allows them to be mounted on every story of a building`s façade. You can light the top floor of a building from close range rather than from the ground, and you don't have to get at the lights every 18 months to replace blown lamps.
More importantly, LEDs have allowed architects to literally cast their buildings in a new light, every few seconds if necessary, by means of dynamic color changes. Arrays of individually dimmed red, green, and blue LEDs can be programmed to fade between any colors in the spectrum.
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