LED Lighting System Design Guidance



(1) Determining lighting needs;

(2) Determining the design target and estimate optics;

(3) The efficiency of the thermal and electrical systems;

(4) Calculate the required number of LED;

(5) Considering all the possible design and choose the best one;


This article will take indoor lighting design as an example, but the design process can be used for any LED lighting designs.


Now LED lighting has general lighting requires, brightness, efficiency, lifetime, color temperature and white point stability. Therefore, most general lighting design will use LED, including roads, parking areas and indoor lighting.

In these applications, no need to maintain (because LED bulbs’ lifetime is much longer than traditional bulbs’) and reducing energy consumption, so the LED lighting reduce total cost of ownership (TCO).


There are more than 20 billion using incandescent lamps, halogen or fluorescent lamps worldwide. Many of these lamps are used as directional lighting, but it is the use of light emitting in all directions. US Department of Energy (DOE) said in a new residential building, embedded dome light is installed by the use of most general lighting.

In addition, DOE reported that the general efficiency of embedded dome light without reflector is only 50%, that is, half of light is wasted in the lighting.


Instead, LED lighting has high efficiency of at least 50,000 hours and directional lighting.

With LED lighting, indoor lighting design has the following advantages:

1 Efficacy is better than all incandescent and halogen lamps.

2 Performance is comparable with the best CFL (compact fluorescent) dome light.

3 Compared with these lamps, the lifetime is longer (5-50 times) before repair is needed.

4 Reduce light impact on the environment: no mercury, small power plant pollution, low garbage disposal costs.


Lighting or Lamps

LED lighting design need to make a choice between the two methods, is based on a complete LED lighting, or it is designed and installed to the LED-based light. In general, a complete lighting design, the optical, thermal and electrical performance is better than the retrofit lamp, because the existing lamps will not constrained designs. For the target application, the overall system performance of new lighting is important, or convenience of retrofit lamp is more important, should be decided by the designer.





Design methods for existing lighting, it is better if the target application uses new structure of LED lighting, then design the light output of the lighting, making it equivalent to or better than existing lighting has several advantages. Firstly, the existing design has been optimized for the target application, it can provide guidance when determining design goals concerning about light output, cost, and work environment. Secondly, the outline of present design is confirmed. If size and shape is the same, it will be easier for the end user to convert it into LED lighting


Unfortunately, some LED lighting manufacturer exaggerates the efficiency and lifetime of LED lighting.

In the early years when CFL replaces light bulb, the lighting industry has similar problems. The lack of industry standards and early differences in product quality has postponed the adoption of CFL technology for many years. DOE realized early LED lighting may also have the same standards and quality problems, and these problems may delay the use of LED lighting in the same way.

In response, the US Department of Energy initiated the "DOE SSL Commercial Product Testing Program (CPTP)", to test the index that LED lighting manufacturer claims. The program tests the following four features of LED lighting anonymously: lighting output (lumens), lighting efficiency (lumens per watt), correlated color temperature (Kelvin degrees), color rendering index.

DOE's CPTP will focus on the lighting available light output, rather than the light output of the lighting, which sets a good precedent for LED lighting design.


The concept of the lamp may be out of date.

LED light with long lifetime may make the concept of the lamp become out of date. LED lighting won’t have catastrophic failure like light bulb.

Instead, before LED lighting gradually degraded to 70% of its original light output flux (also called lumen maintenance), it has at least 50,000 hours lifetime, which means it can be lightened 5.7 years continuously..

However, in most lighting environment, the lamp goes out regularly. This period can extend the lifetime of LED lighting for more than 30 years. Many years later, LED lighting will "burn out" and at that time LED lighting will be brighter, more efficient, compared with the old-fashioned LED lighting, it is likely to save TCO.


Don’t forget: 50,000 hours lifetime of LED lighting avoid the effects on the environment. Incandescent light bulb that is sent to landfill is at least 25 times less, and energy consumption is 5 times less. (For United States, about 50 percent of its energy comes from fire coal, and fire coal will release mercury).


As previously mentioned, no maintenance is an important advantage of LED lighting.

Therefore, for the design of LED lighting, making it the longest life expectancy and save TCO is excellent strategy to deal with high initial cost of LED lighting.

Product Center