June 02, 13
Efficient Lighting: Are LEDs The Answer?
- Efficient Lighting: Are LEDs The Answer?
What is efficient lighting? For that matter, what is inefficient lighting? As many matters are, efficient lighting is relative to the technologies being compared. In the late 19th century when incandescent lighting first appeared it was more efficient than burning candles or a fire in the hearth. Now there are a variety of lighting technologies from which to choose and what is highly efficient for one application might not be suited for another. Factors such as upfront costs, energy consumption, lamp lifespan and light intensity (lumens) all must be considered in determining the best technology for the application needed. There is no “one size fits all” answer.
In the search for the highest efficiency lighting, manufacturers have turned to light emitting diode (LED) technology. In August 2011 the first winner of the ‘L Prize’ competition, established by the U.S. Department of Energy to “spur lighting manufacturers to develop high-quality, high efficiency solid-state lighting products,” was a Philips LED bulb that replaced a standard 60 watt incandescent bulb. It used less than 10 watts while emitting an equivalent amount of light – an 83% energy savings. This bulb is commercially available in the United States but at a reported (as of July 2012) cost of $50 – $60 (without rebates), which demonstrates why incandescent technology has long been the choice of households worldwide: the cheap upfront cost. But as LED bulb manufacturing costs decline they will dominate the world market for lighting by virtues of low energy consumption and exceptionally long lifespan, as a LDE can operate in excess of 50,000 hours (5.7 years) or 50 times longer than an incandescent bulb.
The development of high-efficiency and high-power LEDs have led to applications in lighting. As a rule, LED products are divided into public lighting and indoor lighting and its uses fall into four major categories: visual signals conveying a message, illumination, process measurement and interaction (without human vision) and narrow band light sensors responding to incident light instead of emitting light. Since LEDs can cycle on and off millions of times per second, they can serve as wireless transmitters and access points for the internet.
LEDs have many advantages over more conventional lighting technologies. Their high efficiency is not affected by shape or size, unlike fluorescent lighting systems. They can emit light of a designated color without using color filters, resulting in more efficiency and lower initial cost. They can be very small (less than 2mm squared) and easily attach to printed circuit boards. They can achieve full brightness in under a microsecond. They are ideal for frequent on-off cycling, easily dimmed and radiate little heat. Since they are solid-state components, they are more shock resistant than fragile fluorescent and incandescent bulbs.
There are a number of drawbacks to LEDs; the high initial cost (although forecast to drop exponentially) has been mentioned. Other shortcomings include a limited ambient temperature for optimal performance, voltage sensitivity, and a dependency on correct electrical polarity.
Thus there is no “one size fits all” for the most efficient lighting. But LEDs come closer than any other technology now available.