Top and Side Views of T8 LED Tube Lights vs. T8 Fluorescent Bulb
1. While the initial cost per bulb is still high, the total lifetime cost of an LED light bulb is actually much lower than that of equivalent incandescent and CFL bulbs. Taking into consideration energy costs as well as time and resources required to replace shorter-lived incandescent and CFL bulbs, an LED bulb that lasts 80,000 hours has a much lower lifetime cost.
2. LEDs are diverse, and many types are useless for general lighting applications. The finest LED chips emit light with a Color Rendering Index of 85%. LED light bulbs that use top-quality LEDs will last much longer than the novelty bulbs that many are selling and 60% longer than many competing bulbs that use inferior LEDs.
3. LEDs do generate heat, and this heat is the biggest problem that manufacturers face developing LED lighting applications. Manufacturers can now produce individual LED chips that are as bright as a 100-watt incandescent bulb, but these LEDs are practically useless for general lighting because installing them in a fixture creates ventilation problems that have not yet been solved. LEDs installed in fixtures and bulbs must be ventilated properly, and the better the chip, the more difficult it is to properly cool. There are many LED light bulbs on the market that do not take this into consideration and either use cheap chips so they don’t have to ventilate them, or do not ventilate their chips properly, significantly reducing its lifespan. While the typical LED light bulb is barely warm to the touch, if the chip is not properly ventilated, it can fail prematurely.
LED Tube Light Front and Back (Displaying Heatsink on Back)
4. The life-span of an LED light bulb should be its “half-life.” LED light bulbs do not burn out; rather, they gradually fade out. When a vendor says an LED bulb will last 80,000 hours, they mean that at that point, the chips will have reached 50% efficiency, and the bulb ought to be replaced. So, the bulb might last 100,000 hours or more, but its efficiency will have degraded greatly by that point. Using this 100,000-hour life as a selling point is therefore misleading. While LEDs don’t last forever, they will last 50-75 times longer than a comparable incandescent and 6-8 times longer than a CFL.
5. Searching the web, you will quickly find that the LED light bulb market is inundated with product. Many of these bulbs are relatively inexpensive (less than $20); however, you may find that many of these LED bulbs consist of questionable materials and dubious craftsmanship. Good LED light bulbs cost more than these cheap ones because they use high-quality chips with prices firmly set by reputable manufacturers like Cree. This means that though these LED light bulbs are more expensive, they are far superior.
6. Dimming an LED light bulb is tricky. LEDs require constant current to operate. Because of this, if a standard dimming method is applied, it will flicker at regular intervals, or worse, simply not work. In order to dim an LED light, a 0-10V dimming module is required in order to “trick” the LED into emitting less light. In theory, all LED lights are dimmable with this module.
7. When comparing LED light bulbs, you need to understand lumens. The lumen is a standard unit you can use to compare LED light bulbs to standard bulbs, such as incandescents and halogens. Roughly, a lumen is a measure of brightness. Lumen quantity is important, but maybe more important is lumen quality, i.e., luminous efficacy (lumen/Watt). Today’s quality LEDs have a luminous efficacy between 60-70 lumens/watt.
8. Color temperature and beam spread are the other key tools for comparing LED lights. Both color temperature and beam spread are measured in degrees. Color temperature refers to the color of the light emitted. In general, 3000 Kelvin is warm white (closer to infrared light) and 5000 Kelvin is cool white (closer to ultraviolet light). Cool white is brighter because it is the natural color of LED light, whereas chips that emit a warm white light require a phosphorous “filter” to “warm” the color temperature, thus reducing the chip’s brightness. Beam spread is the angle of the light that is being emitted. The lower the number, the more like a “spot” the light is.
{ 3 comments… read them below or add one }
Helpful soite thanks, but can we have more info about FLICKER? Some makers of fluorescents overcame headache-inducing 100/120Hz flicker with high-frequency drive. So what about LEDS? Surely all they’d need for a continuous flow of light is a simple DC-rectified supply? It would find a market in factory lighting (no strobing) and in film/video media where unsynchronised flicker is a disaster.
My apologies, Jim! I read the site more carefully and you do mention the flicker issue. Can we take it then that all good LED tubes are flicker free, or at least high enough frequency not to affect humans?
Hi Howard, thanks for the comments and question. As you suggested, you can basically assume that all good LED lights on the market today operate at high enough frequencies that this is not a problem. In the US right now there is a bit of a conflict between the manufacturers and the Department of Energy about exactly what the required frequency should be, but even if they settle on the the 120 Hz that the manufacturers are asking for and which is commonly found in lamps on the market today, this will be high enough to ensure that there are no problems.