Lighting industry terminology

- Sep 29, 2018-

Lighting industry terminology

Do you feel overwhelmed by unfamiliar terminology when buying a luminaire or consulting? Still have to understand the meaning of the term Google search? Now I tell you all the terminology in the lighting industry, letting you know ourselves and prevent being pitted.

Luminous flux

- The energy that the light source radiates into the surrounding space per unit time and causes vision, called the luminous flux, expressed by the symbol φ in lumens (lm).


- Used to indicate the strength of the light on the surface (point). The ratio of the luminous flux projected onto the illuminated surface to the area of the illuminated surface is referred to as the illuminance of the surface, and is indicated by the symbol E. The unit of illumination is lux.

Luminous intensity

- the spatial scale of the luminous flux radiated by the light source in a specific solid direction in a specific solid direction (per sphericality), called the luminous intensity of the light source in this direction (abbreviated as light intensity), expressed by the symbol Iθ, in units of candela (cd) ).


-The luminous intensity of the illuminant on the unit projection surface in the line of sight direction is called the light intensity of the surface of the object, and is represented by the symbol L, and the unit is nit (nit).

Color temperature

- When the color of the light emitted by the light source is the same as the color of the "black body" radiated at a certain temperature, the temperature of the "black body" becomes the color temperature of the light source in lumens (K).

Color rendering index

- The degree to which the light source appears to the color of the object becomes color rendering, commonly referred to as the "color rendering index" (Ra).

Luminous efficiency

- The optical performance of an electric light source is expressed in terms of how much lumen flux is produced by consuming 1 W of electrical power, ie the ratio of luminous flux to power, in units of flow/watt (lm/W). The higher the luminous efficiency, the better.

Power factor

- Impact on the power grid, commonly known as grid garbage. The higher the power factor, the less the impact and the better the effect. The ratio of the useful power to the apparent power (the product of voltage and current) in the circuit is denoted by the symbol PF.