Lighting is a comprehensive technology related to electrics and optics, it is one of the important areas in construction electrics application. The purpose of school lighting is to give teachers and students a good teaching and learning environment. A good lighting environment can reduce visual fatigue of students, so that students focus, improving learning efficiency. It can also make teachers relax and improve teaching effectiveness.
A: A Rational Design of Classroom Lighting
Classroom lighting quality is an important factor to the visual health of students, so it must be given special attention. General classroom lighting has two parts, namely desk lighting and blackboard lighting.
1. The lighting requirement for classroom
For the dedicated classroom lighting design, we will make flexible design for the classroom according to the special purpose and installation of equipment, and cannot be solidified into a constant pattern. Such as the illumination of audio-visual electrical classroom should be 1.3 times higher than normal classroom, we should avoid high-brightness light to falls on the screen or other the object to be reflected on the TV screen to make the background brightness and the image loss., When teaching in the audio visual classroom, such as for making the record, require to do part lighting to improve the audi visual teaching quality, pay attention to background and image brightness contrast, we should choose some dimming device from the design. Taking into account the energy-saving requirements, the device does not interfere with the teaching, or have adopted measures to shield the foot, it should use as much as gas discharge lamps to form a reasonable mixed lighting.
B: Desks Lighting Design
1. Higher light source and rational arrangement of lamps
Desk lighting solve by the general lighting from ceiling, the average intensity of desks is 150Ix. Improving the uniformity and illumination of the classroom desks and taking into account energy conservation, LED lamps of higher luminous efficiency should be adopted. The long axis direction of LED lights should be arranged along the line of sight. And the lamp line near the wall is 1/2.5 to 1 / 3 of the two fluorescent lines distance to the wall.
This arrangement can reduce light reflected by the desk and paper, and desks near the wall can also reach the needed illumination level. As students look toward the blackboard in a lecture, they are more sensitive to the direct glare of the lamps. A low intensity light source or Grille lamp should be adopted. When fluorescent light which has a close bat wing distribution curve are used, because the glare area luminous flux of these lamps is less, so the reflected luminous flux is less and visible region aluminous flux more, reducing the direct glare to students seeing blackboard and the reflection when students are writing, improving the visibility class level of the desktop.
2. Rational use of district general lighting control
Classrooms are generally unilateral natural light, during the day time, the window part and the corridor part brightness difference is great, so the lighting should be district controlled, each switch controls as few number of light fixtures as possible When light from the window into the classroom is adequate, only the aisle side row of lights can be opened, that saves energy and distribute indoor illumination evenly.
3. Rational use of illumination automatically switch
Now some people are indifferent on energy-saving awareness, especially in schools and other public places. Some people turn on the lights without lighting need and even keep them lit for the whole day, wasting energy and reducing lamp life. To address these issues, the automatic light intensity switch should be used. The main function of Illumination automatically switch is: when the Desktop surface illumination is more than 150lx, light control circuit is open. Then even if the switch is turned on, the light will not be lit. To prevent the light being lit after the Ex~150lx but there is no people in the room, the switch designs second switching circuit. So when the lights have met the illumination requirements, regardless of whether the light switch is in opening and closing state, we need to re-open the switch to light the lamp. This ensures that lights work only for people’s real need.
C: Blackboards Lighting Design
In the classroom lighting, blackboard lighting is extremely important. Because the board is placed vertically, the vertical illumination on blackboard surface by ceiling lighting alone is not enough, so the board must set up special lighting.
1. Blackboard glare lighting conditions and illumination requirements
After installation of the blackboard lighting, students should not be influenced by the reflected glare but able to see the writing and charts on all parts of blackboard. Teachers should not feel reflective glare when they are writing and no direct glare when they are facing students. When the light source at eye level elevation p% 45 area, it will produce direct glare and the smaller the angle the more intense glare. Designed to avoid the direct glare to students, lamp with protective cover should be used. A teacher should not feel direct glare when they are facing students and teaching, the key is to control the angle between the line of sight and light line. When the angle is less than 60 °, there is faint glare; when the angle is bigger than 60 °, there is glare-free. Measured angle bigger than 55 will reduce the illumination on blackboard. Thus, the general design is to take 55 degree angle. When angle between the light source and top of the blackboard equals to the angle between students and the top of blackboard, it is the basic factor which students feel reflected glare. Greater the angle is, smaller the reflected glare will be. And Blackboard illumination is lower at the same time.
The illuminance requirement of blackboard from “Building electrical design technology procedures”: the vertical illuminance should be more 1.5 times than horizontal illuminance on the blackboard. When we design it, we must consider the uniformity for blackboard and meet the glare restrictions to make the glare restricted as much as possible, and mean while we should use high-efficiency LED fluorescent lighting for the blackboard.
D: Suitable designs for Laboratory lighting
Laboratory can be divided into teaching laboratories and research laboratories with two categories. Laboratory works is characterized by both visual observation of the subtle level objects, but also identify the precise vertical or inclined surface of the object, both the observation of speed of rotation of the object, but also identify the change of the instrument and visual filter. The workplace illuminance of the visible laboratory is the same as classrooms; but the lab requires better vertical illuminance and uniformity in the experimental desk. It should also avoid the stroboscopic effect. So when make the lighting design of the laboratory, focus on solving the following two aspects.
1. "Soft" lighting the way
With the continuous development of science and technology, laboratory equipment has also been updated, some relatively stable teaching laboratories with the development of computers and electronic equipment, there were many vertical bench devices, thereby expanding the scope of the students observation, it is very different to view the objects between current and past, so a fixed lighting fixtures cannot be suitable.
If the fixtures can move freely and are free to change the angle and illuminance in versatile way to achieve a space flexible, it will adapt to work in a variety of experimental lab, the existing rail and multi-functional lighting systems flexible light are parts of this flexible products. Adopted with flexible way of lighting, the lamp power is irrelevant because the actual power is adjusted by the user. Some people predict the future implementation of the flexible way of lighting and lighting standards, it will pay attention to the variety of different work, environmental conditions, personnel and other differences in age and vision, and it will be meaningless only to consider the design of illumination and illumination uniformity requirements.
2. To avoid the stroboscopic effect
As fluorescent light is high efficiency, the current widespread use of lighting in the laboratory, but the fluorescent light work on AC power to change the voltage polarity, when the current become zero, luminous flux will become zero, thus will make the lamp flashes.
Following methods can be used to avoid the Strobe Effect:
1. Single-phase circuits, capacitors can be used to phase-shifting method;
2. Two, three-phase circuits, the method can be split-phase power supply;
3. Electronic ballasts instead of inductive ballast device.