Two Misunderstandings in Current LED Lighting Promotion

As the fourth-generation light source, LED (semiconductor light-emitting diodes) has received unanimous recognition from various countries in the world for its outstanding features such as energy saving, environmental protection, high color rendering, and good environmental adaptability, and has introduced relevant policies to help promote it. After entering the second half of 2007, the luminous efficiency of high-power white LEDs has been rapidly increased. The development of related lighting applications has also entered a period of rapid development, and a large number of LED lamp manufacturers have mushroomed in the industry. LED lamps also appear in the market. However, in the process of rapid development, various manufacturers have also created a chaotic market situation. Blindly exaggerating the energy saving efficiency of LED lamps and unreasonably expanding the scope of application have become the two major mistakes in the process of LED promotion and application. This article will combine the experience of R&D and production of LED lamps over the past four years to express personal opinions on the above two issues.

First, energy efficiency

The theoretical luminous efficacy of LEDs is much higher than that of previous generations of light sources, but under the current conditions, LEDs can achieve very high energy-saving ratios only under certain conditions, and there are still large gaps between actual applications and specific conditions. It is impossible to achieve a high energy saving ratio.

Taking the LED tunnel light as an example, there are different opinions on the energy efficiency of LED tunnel lights on the market. However, the overall performance is over-exaggerated and increases the energy efficiency of LED tunnel lights. Some even claim to be able to save energy by more than 80%. It is obviously followed. The facts are inconsistent. The fact that the energy saving ratio of boasting LEDs and the unrealistic expectation of making too much for customers will eventually have a very negative impact on the industry.

Contrasting the energy saving problem of LED lights and conventional sodium lamps in tunnel lighting, two factors can be considered: the efficacy of different light sources, and the effective utilization of different light sources in tunnel lighting.

(a) The light efficiency of different light sources

1, high pressure sodium lamp

High-pressure sodium lamps currently recognized by the market as light efficiency level of about 100 ~ 110lm / w, and the characteristics of high-pressure sodium lamps is that the greater the power the greater the luminous efficiency. Such as high pressure sodium GE400W lighting effects can reach 140lm / w or more. Therefore, combining the efficacy of most of the high pressure sodium lamps products on the market, the value of the light efficiency of the high pressure sodium lamps below 400W is 110lm/w, and the value of the high pressure sodium lighting efficiency above 400W is 130lm/w.

2, LED light source

The theoretical luminous efficiency of LED can reach 330lm/w, but the mature products that can be used in the market in large quantities currently have an average light efficiency of about 100lm/w, and some of the internationally renowned companies can achieve a level of about 120lm/w. . Considering comprehensively, the luminous efficacy level of LED can be about 105-110lm/w at present, our value is 105lm/w.

(B) Utilization of different light sources in tunnel lighting

From the previous light efficiency data, we can see that the LED light efficiency level is only above the same level as the high pressure sodium lamp, and even slightly inferior to the high pressure sodium lamp. Where does the LED energy saving come from? I believe that when customers ask this question, they should be able to stump a considerable number of vendors.

Tunnel lighting as a special lighting environment, its requirements are unique. According to the National Highway Tunnel Ventilation Design Code JTJ026.1-1999, to ensure the need for traffic safety and tunnel monitoring, the main consideration of tunnel lighting is the area where the light source shines on the road and the side wall of the tunnel is less than two meters. Tunnel lighting belongs to the category of directional lighting. Therefore, the effective utilization of light is the key to LED energy saving.

1, the effective utilization of high pressure sodium lamp

The light emitting angle of the HPS light source is 360°, so the effective light utilization rate of the sodium lamp bare light source is only about 0.4 in tunnels, which is a special directional lighting environment. After the secondary light distribution is performed by installing the light reflecting device, etc., the high pressure sodium lamp The utilization rate is about 0.50 to 0.60. In the discussion of this paper, the median value is taken as the control value that is also accepted by most design units as 0.55.

2. Effective light utilization of LED light sources
The LED light source belongs to unilateral light emission, and its maximum light emission angle is 180°, which has an advantage in the tunnel lighting environment and its utilization rate is very high. Although the relevant national authorities have not given a definite range of values, but estimated from the unilateral light emission angle of 180 °, the effective utilization of light is at least 0.8, and then through the reflector and other devices for secondary allocation After light, the effective utilization of light can reach 0.9 or more, which is 0.90 in the discussion of this paper.

From the data obtained above, the effective luminous flux of a single tile in the lighting of two kinds of light sources can be calculated, namely:

Sodium lamp (below 400W)=110lm*0.55=60.5lm

Sodium lamp (above 400W)=130lm*0.55=71.5lm

LED lamp=105lm*0.90=94.5lm

It can be seen that the effective luminous flux of the LED is much higher than that of the high pressure sodium lamp.

Similarly, we can calculate the energy saving ratio of LED lamps relative to high-pressure sodium lamps:

LED←→Sodium lamp (above 400W)=(94.5-71.5)/94.5=24.3%

LED←→Sodium lamp (below 400W)=(94.5-60.5)/94.5=36%

Based on the above data, we can further calculate the overall energy saving of a 1 km highway tunnel lighting:

Under normal circumstances, in the 1 kilometer tunnel to strengthen the basic use of 400W high pressure sodium lamp, the total power of about 48% of the total tunnel lighting power, while other lighting uses more than 400W lamps, the total power of 52% of the total lighting power about. therefore:

The overall energy conservation of the 1 km tunnel is as follows:

(48%*24.3%)+(52%*36%)=11.7%+18.7%=30.42%

Now, through the previous calculations, we can know: With the current LED light efficiency levels, the energy efficiency of high-pressure sodium lamps in tunnel lighting applications is maintained at about 30%, and this figure can basically reflect the actual application conditions. However, in actual project applications, because the power of high-pressure sodium lamps is relatively fixed, LED lamps can be modularized and flexibly designed to meet the lighting design requirements while minimizing energy consumption by accurately controlling the lamp power. Ultimately, LED lighting is used. The solution for the high pressure sodium lamp lighting program can reach about 40% -50% energy saving ratio.

Second, the current application of LED

According to the previous calculations and the characteristics of LEDs with unilateral light emission, high color rendering, and good environmental adaptability, it can be further inferred that LED has unparalleled advantages compared to other light sources in the field of directional lighting. On the basis of the same luminous efficiency, the floodlight field has not demonstrated its obvious advantages compared with other light sources for the time being. The actual application effect of various products in the market has also demonstrated such results for us.

(I) Directional lighting

In the field of directional lighting, the light needs to be controlled within a relatively small range. The unilateral light emitting characteristics of the LED become the most competitive advantages, and the effect that can be achieved by the relatively large power of the conventional light source can be achieved. Currently used in the market more successful products are: LED tunnel lights, LED ceiling lights, various spotlights, some small-scale LED wall wash lights, some LED stage lights.

(B) Floodlighting
In the field of floodlighting, LED's unilateral light emission can not play its advantages, but instead requires secondary light distribution to maintain a larger light emitting angle; at the same time, since the light efficiency of LED is in the same level as that of high pressure sodium light, it is in high power. Lamps are even at a disadvantage, so in the current stage of floodlighting, LED has no strong advantage to contend with traditional light sources, and it also causes LED flood lighting fixtures to be very large in design, process and cost control of lamps and lanterns. limitation.

Currently in this area are: LED street lights, pole lights and so on. Take the LED street lamp as an example: At this stage, LED street lamps are basically in a situation of high cost and energy saving. Many manufacturers are boasting that their LED street lights can save energy by 70%. As a result, once the project is launched, either the lighting effect fails to meet the requirements or simply fails to meet its promised energy saving ratio, which seriously damages the market image of LED lighting.

Through the comparison of the two fields, we should see that LED has its obvious advantages in some aspects, but at the same time, in other aspects, LED is still in the disadvantaged environment of “no thankfulness”. Fully aware of the performance characteristics of LED, do not dross, in-depth product development, do not blindly move forward, play the advantages of LED is LED lighting development should go the route.

In summary, LED lighting technology is still advancing at a rapid pace. With the advancement of technology, the elimination of LED light sources to replace traditional light sources is a general trend, and LED light sources will also be used in various fields. However, during the development of LED technology, under the current technical conditions, the characteristics and advantages of LED are analyzed calmly, and product development is carried out in-depth and down-to-earth to enhance the value of its products. At the same time, it is truly capable of creating value for customers. LED manufacturers should stick to the road. Blind exaggeration, only focus on hype instead of focusing on the true value of the product, do not pay attention to creating value for customers, the ultimate harm is not only the company itself, the development of the entire LED lighting industry will have a very serious negative impact.