In the traditional understanding, lighting is just to provide us with light in the dark, we use the most white fluorescent lamp. However, with the improvement of living standards, our demand for lighting is also higher and higher. In addition to providing us with good visual conditions, we can also create different styles and aesthetic indoor environment to meet our psychological and physiological needs. So what are the lighting considerations?

1. Light source

The light source is divided into natural light source and artificial light source.

Natural light source is divided into self luminous and non self luminous. The most common self luminescence is the light emitted by “combustion”, such as lightning and sunlight (nuclear fusion in essence); the other is bioenergy light sources, such as fireflies, multi tube jellyfish and sea bamboo shoots. Non self luminous light sources include sky light, moonlight, etc. glowworm

Artificial light source: artificial light source is the light source made by human beings. From combustion to electric energy, the common ones are torch, oil lamp, candle, electric lamp (incandescent lamp, fluorescent lamp, high-voltage xenon lamp), etc.

What should be considered for all lighting?

2. Color temperature

If the ratio of absolute blackbody at a certain temperature to the spectral radiance of an actual object at two wavelengths is equal, then the temperature of the blackbody is called the color temperature of the object, also known as the colorimetric temperature or spectrophotometer temperature.

Because the spectral emissivity of an actual object increases or decreases with or increases with or is approximately independent of the wavelength, the color temperature of an object may be greater than, less than or approximately equal to its true temperature. A colorimetric pyrometer is used to measure the color temperature.

3. Average illumination

The luminous flux received per unit of illuminated area s is called illuminance E in LX.

The average illumination is used to measure the brightness of a scene.

Average illumination (LX) = lumen (LM) × utilization coefficient × maintenance coefficient △ area


The luminous flux unit (LM) of the light source, and the luminous quantity of the light source emitted by the light source in unit time is called the luminous flux F. The higher the lumen number, the brighter the brightness.

Utilization coefficient:

The utilization factor is the ratio of the luminous flux received directly or by mutual reflection on the working reference plane to the sum of the rated luminous flux emitted by all lamps of the lighting device. In order to avoid large deviation, the lighting design must have accurate utilization coefficient. (definition from Baidu Encyclopedia)

The main factors affecting the utilization coefficient are the light distribution curve of lamps, the light output ratio of lamps, the indoor reflection coefficient and the arrangement of lamps.

Maintenance factor:

After a period of work, the ratio of the average illuminance (i.e. maintaining illuminance) generated by the lighting system on the working surface and the average illuminance (i.e. initial illuminance) when the system is newly installed. (definition from Baidu Encyclopedia)

The coefficient is related to whether the average illuminance of lamps can be maintained after one year’s use.

The main factors affecting the maintenance coefficient are the failure value of fluorescent tubes, the adhesion dust of fluorescent tubes and lamps.

4. Color rendering

The color rendering ability of a light source to an object is called colorability, which is the comparison of the appearance color of an object under the reference or reference light source (incandescent lamp or drawing light) with the same color temperature. There are two situations:

Faithful color rendering: the light source that can correctly represent the original color of the material has a high color rendering index (RA) close to 100, and the color rendering performance is the best.

Effect color: using the method of adding color to enhance the color rendering effect, so as to highlight the specific color more clearly. For example, using low color temperature light source to make red more bright; using medium color temperature light source to irradiate blue; using high color temperature light source to irradiate objects with cold feeling.

The relationship between color rendering index and color rendering property: when there is little or no main wave reflected by the object under the reference light source in the spectrum of the light source, the color will produce obvious color difference, and the greater the color difference, the worse the color rendering of the light source to the color. The color rendering index of incandescent lamp is defined as 100, which is an ideal reference light source.

5. Uniformity

Uniformity is the light and shade contrast of indoor lighting. In order to achieve the most appropriate illumination, it is necessary to adjust the number of lamps and lanterns.

Uniformity = the lowest illumination value in the illumination area × the highest illumination value in the illumination area

In general, the ratio of average illumination in general area to that in working area is 1:2

6. Comfort

Lighting comfort is to avoid glare caused by direct light source into eyes. For example, the ceiling lamp will produce glare on the computer screen, making our vision very uncomfortable.

7. Security

Safety is no small matter, in the lighting system, because the main use of electric energy source, so the safety must cause enough attention. It is necessary to consider whether the quality of lamps, wires, parts, etc. conform to the national standards, the design and installation shall comply with the safety standards, and the use process shall follow the safety manual.

Editor in charge: WV

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