What Should We Pay Attention To When Applying LED To Classroom Lighting

- Feb 20, 2019-

As a solid-state semiconductor light source, the light efficiency of LED has been improved continuously in recent years, and the price has been declining. Compared with traditional light sources, LED has many advantages, such as small size, adjustable and controllable, long life and so on. LED lighting products have gained rapid development and extensive attention in many application fields, such as classroom lighting.


In this paper, we discuss the question of whether LED light source can be used in classroom lighting at the present stage, which has aroused discussion and query in the society. The purpose is to make a clear distinction between relevant concepts and convey the correct understanding of relevant issues to people.


Controversy over the Use of LED Light Sources in Classroom Lighting


At present, there are two main disputes about whether LED light source can be used in classroom lighting at this stage.


1) Today, with the rapid development of LED technology, LED lamps are gradually replacing the mainstream "rare earth tricolor fluorescent lamp" used in classroom lighting. Does the current national standard of classroom lighting allow and recommend the use of LED light source?


2) Under the background that the quality of lighting products has been paid more and more attention and blue light hazards, stroboscopic and other issues have become social hot spots, does LED light source pose potential safety hazards to children's visual health during their development?


Does the National Standard Allow Classrooms to Use LED


Current effective classroom lighting standards include "Health Standards for Classroom Lighting and Lighting in Primary and Secondary Schools" (GB7793-2010), "Design Standards for Primary and Secondary Schools" (GB50099-2011), "Design Standards for Classroom Lighting in Primary and Secondary Schools and Kindergartens" (DB31/539-2011), "Design Standards for Building Lighting" (GB50034-2013), "Technical Standards for Energy Saving Certification of Classroom Lighting Products in Primary and Secondary Schools 5-2016) Requirements are made for the average illumination and illumination uniformity of the classroom, blackboard, uniform glare value, color rendering index, color temperature of light source, luminaire efficiency and power density. These standards are applicable to all kinds of light sources.


Whether LED or traditional light source, the corresponding parameters for classroom lighting should meet the requirements of lighting standards for various indicators.


Because of the development and popularization of LED lighting products, it is necessary to standardize LED lighting in classroom. At present, China Quality Certification Center (CQC) issued the Technical Specification for Energy Conservation Certification of Lighting Products in Primary and Secondary Schools and Kindergartens in 2016, which further regulates the parameters of LED products. Other standards for LED lighting in classroom need to be improved.


Does LED Light Source Have Safety Hidden Dangers


At present, the light efficiency and luminaire efficiency of white LED for general lighting have exceeded that of traditional light source, and can achieve high color rendering and stability, which can meet the dimming requirements of intelligent lighting. The use of LED depends on whether the final lamps can meet the requirements of lighting indicators and related lighting devices.


As for the Photobiological Safety of LED, we can refer to the white paper "General Lighting LED and Blue Light" published jointly by the International Semiconductor Lighting Alliance, the National Semiconductor Lighting Engineering Research and Development and Industry Alliance and the Chinese Lighting Society in July 2013. It is clearly mentioned in the white paper that the correct use of qualified white LED products for general lighting is completely safe for human eyes.


At present, public opinion has many concerns about Blu-ray, but we can not blindly deny it.


On the one hand, blue light is an important component of white light. It not only plays an important role in guaranteeing color rendering, but also regulates physiological rhythm. Outdoor sunlight can synchronously regulate human physiological rhythm (or biological clock). Indoor blue light radiation is much less than outdoor activities. Blue and cold white light sources can be used to establish a suitable light environment and help people obtain the daily dose of blue light to ensure that their physiological rhythm is in harmony with the natural circadian rhythm.


On the other hand, the "blue hazard" we usually hear refers to the photochemistry damage of the retina caused by the long-term direct vision of the light source in the 400-500 nm blue band of the light source if the radiation brightness is too high. The essence of blue light problem is the combined effect of radiance, blue light weighting function and time. Spectrally, the proportion of blue light in the LED spectrum increases when the color temperature increases, but there is nothing special compared with the blue light in the fluorescent lamp spectrum. When the color temperature is the same, the upper limit of the safe brightness of the blue light of the LED is similar to that of the fluorescent lamp.


There is a unified rating standard for Blu-ray retinal hazards at home and abroad, GB/T 20145-2006/IEC62471. The daily common lighting LED lamps belong to grade 0 or grade 1 and belong to the safety category.


What should we pay attention to when using LED in classroom


At present, there are some problems in the use of school classroom lighting LED lights, such as confused brand, uneven quality, non-standard market, lack of regular maintenance, and imperfect standards, but we can not blame the problem on the LED light source itself.


Classroom lighting in the use of LED products should pay attention to the following issues:


First of all, the selected LED products should meet the standard requirements in terms of light and color quality, including safety level requirements, performance requirements, reliability requirements, environmental protection laws and regulations requirements, etc.


Secondly, the light source and lighting system should be used correctly, including reasonable lighting design, correct installation, regular inspection and maintenance, etc.


Lastly, all kinds of light sources and lighting system products should be tested for photobiosafety. Even if they are safe and do not need additional warning signs based on the standards, users should avoid looking directly at these light sources for a long time, especially at short distances.