The biggest advantage of LED lights is the directional light distribution. We know fluorescent, metal halide, mercury vapour and high pressure sodium lamps all have a 360 degree lighting angle which means that just small amount of lights go directly to place where needed. The rest of it has to be reflected by shade or reflector with big loses. However LED lights don’t have this problem.
LED lights are inherently directional light sources and offer better optical control than alternative older light sources like fluorescent, metal halide, mercury vapour and high pressure sodium lamps. LED lights can produce the same high light levels on nearby surfaces or lower light levels on more distant surfaces with fewer total lumens than these alternatives. To maximize energy efficiency and lighting quality, it is important to evaluate each lighting option against the specific light level. For more information’s please visit: (Link to LED lighting design proposal)
Figure 1, Figure 2, Figure 3 show the advantages of directional LED light fittings in this application. Omnidirectional Metal Halide lamps do not transmit all their light toward the target to be illiminated, resulting in losses within the fixture. The directional LED light fittings transmits all its light toward the target, with minimal to no losses within the fixture. As a result of this difference a lumens-for-lumens match between an LED light fittings and Metal Halide lamp is only partially relevant.
|Figure 1: Typical High Power LED light distrinution||Figure 2: Typical High Bay Luminaire light distribution||Figure 3: Typical Metal- Halide lamp distribution|
Directional light distribution
|429 W||29008 lm||20 919 lm||54%||15 781 lm||36.7 lm/W|
|Metal Halide clear
|429 W||29 008 lm||26 780 lm||61%||17 608 lm||41 lm/W|
* Usable Lumens is the light in zone 0-60° lumen distribution. The rest of the light is considered to be wasted.
The fixture efficiency is the reflected light that is usefully and light up area we need.
LED vs. other light sources
Metal halide / mercury vapour lamps have become a favourite light fitting for warehouses and other high-ceiling applications. However, the shortcomings of metal halide technology include extended warm-up times, lengthy restrike delays, emission of UV radiation, poor dimming capabilities, and even new metal halide and mecury vapour light fittings can fail in restrike (about 10% of the time).
In comparison, LED lights generate bigger lumens output than metal halide for the same wattage, with LED lamp life currently ranging from three to seven times longer than metal halide. In addition, LED sources are perfectly suited for dimming and occupancy controls. Also LED offer precise and directional light distribution. (Table3.1) And LEDs neither contain nor emit toxic material.
While CFLs shortened the warm-up time and eliminated the restrike issues associated with metal halide lamps, they introduced their own set of drawbacks.
CFLs suffer reduced output in higher temperatures causing premature lamp failure. They also contain toxic materials (mercury, lead), requiring regulated disposal procedures. Their rated