A good lighting environment plays a very important role in the life and learning of primary and secondary school students.
Primary and middle school students are in adolescence with a large accumulation of knowledge and rapid development of the body. A good lighting environment not only enables students to quickly integrate into the learning environment of the corresponding subjects, but also forms a lasting and effective scene memory and knowledge accumulation, focusing on learning and examination. It can also reduce the frequency and duration of visual fatigue, reduce the irritating degree of glare to the eyes, reduce the external factors caused by myopia, and enable students to have a good feeling of physical and mental pleasure, thus helping students achieve better learning and healthy growth.
1 primary and secondary school classroom lighting requirements
At present, China's documents on the lighting of primary and secondary schools mainly include GB 7793-2010 "Standards for Lighting and Lighting in Primary and Secondary Schools", GB 50099-2011 "Code for Architectural Design of Primary and Secondary Schools" and GB 50034-2013 "Architectural Lighting Design" standard". In addition, in the actual classroom lighting practice in various regions, local technical standards have been compiled according to regional characteristics, the most representative of which is DB 31/539-2011 “SMEs†issued by Shanghai in 2011. And kindergarten classroom lighting design specifications, for the classroom lighting design of primary and secondary schools to carry out comprehensive and detailed specifications. The above standards and specifications require requirements for illumination, uniformity, color temperature, color rendering index, glare and power density of classroom lighting (see Table 1). From the perspective of the continuous updating of classroom lighting standards from the country and the region, there is no doubt that progress has been made. But unfortunately, on the one hand, based on the current general situation of classroom lighting in China, the illuminance requirements are generally lower than those in developed countries such as Europe, America, and Japan (see Table 2). On the other hand, despite the quality of lighting in the standard. There are requirements, but there are no clear provisions for the specific test measurement, evaluation and evaluation methods, and there are certain impairments in the implementation of the specific provisions of the standard specifications.
2. The problem of classroom lighting in primary and middle schools in China
At present, most of the primary and secondary classroom lighting in China use fluorescent tubes as the light source, or directly use the "lamp bracket (including electrical components) + bare tube" method, or apply "lamps (grid panel / blackboard lamp) ) + fluorescent tube light source mode to achieve basic lighting and blackboard lighting in the classroom (Figure 1).
Most of these forms of lighting have the following problems:
1) The desk illumination is generally insufficient. According to the lighting survey results of 99 school buildings in six regions of China, the measured illuminance of the classroom is mostly between 200lx and 300lx, and the average illuminance is 232lx. The actual illuminance and design illuminance are both low (Figure 2).
2) Blackboard illumination is poorly uniform. Generally, a fluorescent tube (or a reflector) is used as a blackboard light, so that the upper part of the blackboard is too bright, so that the student can easily distinguish the white of the upper blackboard.
The chalk word, while the lower part is too dark, the illumination is insufficient, and the students can't see the written content (Figure 3).
3) Glare is obviously irritating to the eyes. In the classroom, the general lighting is covered by a lamp holder + fluorescent tube. The light source is exposed. The students can easily see the light source directly and the eyes are stimulated. The use of the grille lamp plate has some improvement, but it cannot be completely avoided. Blackboard lights, such as the use of fluorescent tubes directly, students and teachers will be affected by their glare, affecting the efficiency of learning, such as by adding a reflector, although students can avoid glare, and teachers will be stimulated by glare (Figure 4 ).
4) High color temperature is easy to cause visual fatigue. There are still many classroom lightings that use fluorescent tubes with a high color temperature of 6500K. Studies have shown that high color temperature illumination can make people concentrate and improve vigilance, but long-term high color temperature illumination is easy to induce visual fatigue, which leads to psychological fatigue. Therefore, the effect of long-term memory is not good, and even leads to psychological Generate negative emotions such as anxiety and boredom.
5) The overall energy consumption is high. From the perspective of survey classroom lighting, the lighting configuration of a single classroom in a general standard primary and secondary school classroom is mostly "3 × 3 × 2 + 3", that is, three rows and three columns of double-tube 40W light panels (mostly T8) as classrooms. The basic lighting, plus three 40WT8 fluorescent tubes (or equipped with reflectors) as the blackboard illumination, the total power consumption is about 840W, comprehensively calculate the lighting power consumption and electrical loss of all grades of the entire school, the energy consumption is not low. In addition to the above main problems, the use of fluorescent tubes as classroom lighting sources, there are also deficiencies in stroboscopic, noisy, short life, etc., affecting the quality and effectiveness of teaching activities.
3 LED intelligent lighting application in primary and secondary classrooms
As a fourth-generation lighting source, LED has achieved certain technological research results and is widely used in road lighting, commercial lighting, office lighting and other fields. From the actual use situation, it has achieved good lighting effects and energy saving effects. In the field of classroom lighting, although some manufacturers use LED tubes to replace fluorescent tubes, they have achieved certain success in energy saving, but they still cannot change the overall predicament of classroom lighting.
3. 1 LED intelligent lighting system introduction
The author's R&D team carefully studies the characteristics of classroom lighting, analyzes the different effects of light color on the human sensory perception and memory, and combines the natural laws exhibited by people at different times to find a balanced image in LED lighting characteristics and classroom lighting needs. Binding point. Through unremitting efforts, we have integrated knowledge related to many disciplines such as light color, biology, intelligent control, thermodynamics and mechanical structure, and innovatively established the concept of “four-dimensional lighting†to develop a set of intelligent lighting suitable for standard classrooms in primary and middle schools. The system, after practice, has solved some problems existing in classroom lighting in primary and secondary schools, and provided comprehensive solutions for the lighting needs of primary and secondary classrooms. In classroom lighting, in order to avoid the relative glare caused by the excessive brightness difference between the desks and the blackboard, the main focus is on the illumination of the horizontal level of the desk, including the ground illumination and ceiling. The illuminance of each surface, such as illuminance and blackboard illumination, basically covers the lighting of the entire three-dimensional environment of the classroom. In addition, considering the color temperature and brightness changes of natural light in different time periods, and the physiological changes of the human body in different periods of the day, intelligent control technology is used to set the illumination modes with different effects in different time periods, that is, the time is the fourth axis, plus The three dimensions of the upper lighting space constitute the core idea of ​​“four-dimensional lighting†(Figure 5).
The whole set of “four-dimensional lighting†elementary and middle school classroom intelligent lighting system is mainly composed of four core modules (Figure 6), which is the three-dimensional lighting LED lamp panel responsible for the main lighting of the classroom, the polarized LED blackboard lamp for blackboard illumination, and the embedded in the lamp. High-precision photosensitive system and intelligent control system for connecting various lamps, photosensitive devices and controlling different lighting modes.
3.2 Characteristics of LED intelligent lighting system
The LED intelligent lighting system has the following features:
1) Stereo illumination LED panel provides indirect reflection illumination by adding long-distance projection on both sides and back-side illumination, increasing the illumination and uniformity of the overall space. Due to the dispersion of the illumination direction, the surface illumination brightness of the main exit surface can be controlled. An anti-glare grille is used on the light-emitting surface to ensure that the main light-emitting surface is directly glare-free (Fig. 7).
2) Polarized LED Blackboard Lights Design polarized lenses through proprietary technology to achieve 90° ~ 270° plane light distribution for vertical illuminance, and more light effects are projected onto the bottom of the blackboard to reach the lower part of the blackboard. The illuminance is more consistent, and 0° ~ 180. The flatness of the plane is not limited to the shadow of the two blackboard lights, to ensure that the uniformity of the blackboard illumination is 0.8. At the same time, pay attention to the light interception through the light interceptor near the outer end of the hood, to avoid the teacher directly stimulated by the light source light during the blackboard writing process (Figure 8).
3) Through the high-precision photosensitive system of the built-in luminaire, the illuminance at the projection surface of the luminaire is up to a preset value, and the illumination uniformity greater than 0.8 is achieved by the automatic adjustment, in accordance with GB 50034-2013 "Architectural Lighting Design Standard" The illuminance uniformity specified in the above is greater than 0.6. Whether the natural light outside the classroom is on a cloudy or sunny day, whether it is in the day or night, it can be accurately positioned to the corresponding illuminance position (Figure 9).
3) The intelligent control system sends control signals to the lamps through the control chip compiling software, which can effectively adjust the light output and light color changes of each main illumination LED lamp to match the lighting requirements of different disciplines, different time periods, and different teaching activities.
4) After the combination of different brightness and color temperature
Condition (the brightness is adjustable, the color temperature adjustment range is 3000K~5500K). The investigation on the influence of human memory and physiological changes has found that different lighting conditions correspond to liberal arts teaching, science teaching, self-study, breaks, exams, etc. The positive role of teaching activities, including the "arts" and "science" in the intelligent control system,
"Self-study" a variety of lighting scenarios such as "exam" lunch break in the class, and according to the order of the school curriculum, self-programming and combination, set the lighting program of the whole semester of the classroom, and realize the automation and intelligent management of classroom lighting ( Figure 10).
3.3 Application Case Analysis
3.3.1 Blackboard light use effect
1) LED blackboard light simulation effect. To verify the matching of the blackboard light
For the light performance, the blackboard light was placed in a classroom 3D scene with a length of 9.0 m and a width of 7.0 m, and the lighting simulation was performed using Dialux lighting simulation software. When the output light flux of the blackboard light is 2600 lm, the maintenance factor is 0.8, and the simulation effect and data are shown in Fig. 11 and Fig. 12, respectively. It can be seen from the simulation results that the parameters such as illuminance and uniformity meet the standard requirements.
2) The actual effect of the blackboard light. After the development of the blackboard light is completed, the author team selects a school classroom for actual installation testing. As shown in Figure 13, the length of the blackboard is 4. 0m, the width is 1. 2m, the position of the illuminance test is referred to the central point of the illuminance measurement in GB/T 5700-2008, the recommended test point spacing in the standard is 0. 5m × 0. 5m. The grid is preferably square. Considering the size of the blackboard is 4. 0m × 1. 2m. On the basis of the reference standard, we adopt a stricter spacing of 0. 4m × 0. 4m for meshing. During the test, the blackboard is divided into 30 (10 × 3) square grids. After the length is measured, the corresponding position on the center of each square grid is labeled as a point marker.
The illuminance meter is used to perform the corresponding illuminance test at each point on the surface of the blackboard, and then the data is calculated to calculate the average illuminance and illuminance uniformity of the blackboard surface, and the illuminance data of each point is measured as shown in Table 4.
According to the test illuminance value, the average illumination value of the blackboard surface Eav1 = 663lx and the minimum illumination value Emin1 = 550 lx can be calculated, and the uniformity of the illumination on the blackboard surface U01 =0.83 can be calculated. The illuminance test value is the new value of the luminaire. After considering the maintenance factor of 0.8, it can be seen that the illuminance of the blackboard surface is maintained at 530lx, which is consistent with the simulation results of the scene, and meets the requirements for the illumination of the blackboard in each standard.
Figure 14 shows the lighting effect of a classroom blackboard after using the blackboard light developed by the author team. It can be seen that the illumination uniformity of the blackboard is good, and there is no bad situation in which the upper part of the blackboard is bright, and the lower part is obviously dark, which is much better than the traditional blackboard light effect.
3. 3. 2 LED intelligent lighting system use effect
1) LED intelligent lighting system simulation effect.
The author's R&D team selected a typical representative classroom with a length of 9. 0m and a width of 7. 0m, and built a 3D model of the classroom using Dialux lighting simulation software. The designed LED luminaire data is imported into the scene model for lighting simulation calculation to verify the feasibility of the design scheme. The overall space lighting effect is shown in Figure 15.
Stereo illumination LED lamp panel When the total luminous flux of each panel is 3000lm, in the 0.75m horizontal plane (class height of the desk) 7. 0m X5. 6m in the student desk area, the illumination maintenance value (maintenance coefficient is 0.8) is 336lx, illumination The uniformity can be achieved at 0.82. The illuminance gray scale map and simulation results of the detection area are shown in Fig. 16. According to the simulation results of the lighting scene simulation, the author team found that the three-dimensional illumination LED lamp panel with side illumination and back illumination added as described in Section 3.2) has a good performance in increasing the illumination uniformity of the three-dimensional space and reducing the spatial glare effect. .
2) The actual effect of LED intelligent lighting system. As described in 1), after simulation analysis, the stereo illumination LED panel performs well in increasing the uniformity of illumination in three-dimensional space. Based on this, the author team developed specific LED lighting fixtures, combined with LED blackboard lights and intelligent control system, to form an LED intelligent lighting system, and test installation in the corresponding classroom of the simulation scene. When the lighting system is adjusted to the normal teaching mode, the blackboard light and the LED main lighting panel are lit at the same time, the color temperature is adjusted to 4000K, and the brightness is adjusted to medium brightness. Refer to the central point method of illumination measurement in GB/T 5700-2008 at 0.75. m water level (class height of the desk) 7.0m X 5. 6m 5 in a 6m area, a total of 30 points test illuminance, measured illuminance values ​​as shown in Table 5.
According to the test illuminance value, the average illuminance of the entire classroom is calculated as EaV2 = 427 lx, and the minimum illuminance value E-2 = 347 lx, and the illuminance uniformity is calculated as U02 =0. 82, and the illuminance value is considered to be a maintenance factor of 0.8. The latter is 342lx, which is consistent with the value of the Dialux scene lighting simulation. The LED intelligent lighting system can meet all the standard illumination and uniformity requirements of classroom lighting.
Figure 17 shows the actual lighting effect. When the LED intelligent lighting system works, in addition to illuminating the desktop area under the lighting, the light emitted from the back and sides of the lamp can also illuminate the upper space of the classroom, making the lower and upper parts of the classroom space. The contrast of the spatial brightness is reduced, which reduces the sense of spatial depression caused by the upper part of the classroom; it also reduces the glare effect and increases the comfort. It can be used in normal lectures to improve the psychological and sensory comfort of students and is beneficial to the psychological development and growth of students.
In addition to the above-mentioned light-emitting surface controllable, the LED intelligent lighting system can also achieve functions such as controllable brightness and controllable color temperature. It can be adjusted and matched according to the needs of different occasions. Such as low color temperature and low brightness can be used for lunch break during the class, to create a comfortable and quiet rest environment for students; medium color temperature medium brightness can be used for normal teaching and self-study time; high color temperature and high brightness can be used for hands-on classes, debate classes, etc. Encourage students' emotions and participation in enthusiasm.
3.3.3 Unified Glare Value (UGR) Assessment
The LED intelligent lighting system selects five typical position points to evaluate the system _ glare value (UGR) in the working state described in section 3.3.2. As shown in Figure 18, the five locations in the classroom represent the location and the UGR evaluation values ​​are:
1) The middle student position in the back row, UGR = 12; 2) The edge of the blackboard where the teacher is located, UGR = 12; 3) The normal teaching position of the teacher, UGR = 10; 4) The student position in the front row, UGR = 13; 5) Student position in the back row, UGR = 14.
Among them, the height of the test probes at 1, 3, and 5 points is 1.2m in height. The height of the test probe is 2m. The height of the test probe is 2m. The height of the eye on the teacher's podium is 1.5m (distance from the podium). The evaluation results show that the glare value limiting method adopted in the LED blackboard lamp and the lamp panel design process has a very obvious effect, and the UGR value of the classroom space can be reduced to below 16 to meet the requirements of the human eye to observe the object comfort.
4 Conclusion
Primary and secondary schools are places where students live and study for a long time. A healthy light environment plays a positive role in promoting the growth of primary and secondary school students. Our precise light distribution design, balanced product design and intelligent LED system design have improved the quality of classroom lighting. Through the practical application and test verification in some pilot classrooms, the LED intelligent lighting system designed by the author has improved the teaching quality, the visual perception of teachers and students, the memory effect of students, and the reduction of energy consumption.
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