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[Editor's note: William Dinkel, an avid blogger on green technologies and energy efficient solutions, contributed to the reporting and research for this article.]
The capability to provide artificial sunlight has dramatically expanded the boundaries of time and space, adding hours to the day when we may see and illuminating where sunlight was unable to penetrate. Since the first humans carried a torch to provide light, heat has been a by-product of producing light.
Traditional electric lights continue to give off more heat than light. An incandescent light bulb uses a paltry 10 percent of its energy to create light. Fluorescent lighting -- which has been the green standard in energy efficiency -- still wastes nearly half of the electricity it consumes in generating heat. All of this lost energy is significant considering that lighting devours more than a quarter of a typical commercial building's electricity, as reported by the U.S. Energy Information Administration.
LED, or light emitting diode, fixtures, in comparison, are twice as efficient as fluorescents at converting electricity to light and hence generate very little heat. In addition to improved energy efficiency, LED fixtures are nearly maintenance free and provide high quality of light. They are also dimmable, contain no mercury and tolerate frequent on/off switching without degrading their lifespan.
LED Case Studies
Since UCSF Medical Center replaced some of its surgical lighting with LED fixtures, doctors and nurses no longer complain about the heat from the light fixtures when performing surgical procedures.
"Previously we had to chill the OR [operating room] to offset the heat generated by the old fixtures," UCSF Project Manager John Lewis explained. "The new LED lights do not radiate heat and the OR medical staff is comfortable at standard OR temperatures."
Quality of light is an important issue to adoption of any new lighting technology. Fluorescents were unable to replicate the incandescent bulb's soft and pleasing glow and disappointed both professional lighting designers and the cube dwellers who toiled under their unnatural glare. LEDs hark back to a more basic light source, the sun. The spectrum and color rendition come closest yet to natural daylight.
An LED is a semiconductor that creates light by releasing energy from electrons. It is frequently referred to as "solid state" or "digital" lighting. Because LED fixtures generate light over an area using thousands of tiny light sources, the fixtures also provide a clear, shadow-free light field that is ideal for task work, whether an accountant, engineer or surgeon.
"The most important criteria for our application is the quality of light. After an early test, we eliminated fluorescent fixtures since fluorescents render colors poorly," Lewis said. "The medical team found the quality of light provided by the new LED lighting was superior to the existing incandescent lighting."
While quality of light is important, CFOs, facilities managers and contractors also want to understand the financial benefits of LED fixtures. LED lighting providers emphasize the lower total cost of ownership offered by LED lighting to justify the higher upfront investment.
Next Page: The cost benefits of LEDs and barriers to their adoption.
Do a little more research
LED's are not twice as efficient as fluorescent. At best their equal. And there is a wide gap in performance between the worst and best. So junky LED's are only as efficient as an incandescent.
LED's still create heat. This is the biggest myth that articles like this keep spreading. Heat is based on Watts of power consumed. Anyone with a 9W LED task light at their desk will tell you they get warm.
That EIA says lighting makes up 44% of the electricity load of a typical office and 56% of a typical school. Not 25% as the article states.
No light is shadow free. If anything LED light creates more shadows than linear fluorescent since it has a smaller surface area than fluorescent.
Don't believe any published LED fixture life if it wasn't tested per LM-80. The typically published 50-100k hour lamp life is based on only the LED, not the complete fixture. The cheap fixtures don't manage heat well and the high heat levels on the circuit board cause early failure. Only months for some fixtures. LM-80 tests the fixture as a whole.
If you look close enough at the ROI numbers provided by manufacturers, nearly all of the "energy savings" is in reduced maintenance, and most of that savings is inflated.
LED v fluorescents - not even close
LED's might be more efficient at producing light as your article says, but what happens to the light afterwards is also key. LED lighting is often extremely directional, needing diffusers to spread the light around and thereby decreasing the efficiency. As a result, even cutting edge LED lighting solutions aren't any better than T5 or other fluorescent technology but cost much much more, even over the extended lifetime.
Here's an example LED / fluorescent domestic lighting cost-benefit comparison. The numbers sometimes stack slightly in favour of LED solutions, but often only when the spread of light isn't taken into account. This has an important health and safety dimension in many working environments: for example, many LED lighting solutions in warehouses do a good job at lighting the floor but a poor job at lighting the racking.