By Stan Walerczyk
Hopefully you already understand some very important facts about LEDs and LED products, but there are several myths that some distributors and contractors take as truth, when they are not.
This column completes my list of seven LED myths. Find the previous three here.
MYTH 4 – LEDs are better for the environment than all other high performance technologies
Although some LED product manufacturers and sales people state something like ‘toxic’ in front of fluorescent and other lighting technologies, and try to make LED look perfect, that is not really the case. No, LEDs do not have any mercury, but mercury levels in fluorescent lamps have really come down and they can be recycled. Although 4′ T12 lamps used to have about 50 mg of mercury, now numerous existing 4′ T8s only have 1.75 mg and numerous 4′ T5s only have 1.00 mg. If you are not already aware, a can of tuna fish usually has much more mercury than a CFL. There is a lot of metal, usually aluminum, heat sinking in LED products, and the metal has to be mined, melted, transported, melted and transported again, all of which takes considerable energy. When the LED fixtures are decommissioned, the metal should be recycled, which also takes energy. Just like when you buy a new TV or computer, a portion of that cost pays for the recycling process when you want to get rid of those electronic products. There has been discussion of including LED products in recycling. Plus, some extra long life fluorescent T8s last longer than many LED products.
MYTH 5 – Controls are usually cost effective with LEDs to save energy
LED products are getting so low wattage that often neither basic controls, such as occupancy sensors, or advanced controls are cost effective saving energy in many projects. For example, where an occupancy sensor used to be cost effective by controlling 80 watts of ambient lighting, it is no longer cost effective, now only controlling 40 watts, because the electric consumption is so small. So instead of doing what you may have been doing, which is specifying both lighting and controls, it may be better doing more lighting and less controls. But there are certain projects that lighting with controls or just controls are adequate to save energy.
MYTH 6 – Since LED drivers are high frequency, flicker is not an issue.
First of all, there are two types of flicker. One type you can see, and the other type you cannot see, but you can perceive. Both types can reduce visual acuity and cause eyestrain, headaches and even seizures in some people. Many of us thought that flicker went away as magnetic ballasts went away. But flicker can be a very significant problem with LEDs especially with wave-chopping dimmers and pulse width modulation drivers. Flicker is usually worse with deep dimming. You can detect the non-visible flicker with your cell phone camera. There will be horizontal lines in the viewfinder. Try to avoid LED products that flicker.
MYTH 7 – LEDs and other technologies with same Kelvin highlight objects about the same.
Merchandise lit with a 2700K LED PAR lamp can look quite different than being lit with a 2700K halogen PAR lamp. Skin tones can look quite different lit by 3500K fluorescent or 3500K LED. Watching a basketball game can look quite different with 4000K ceramic metal halide or 4000K LED. Not only is this inaccurate, but various LED products with the same Kelvin or correlated color temperature (CCT) can make objects look quite different, because different types or combinations of LEDs can be used. Kelvin-CCT or color rendering index (CRI) are not longer sufficient. Spectral distributions and R1 – R14 should be used. CRI is only R1- R8, which are only pastel colors.
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