Illuminance (Lux)

Illumination or illuminance is the total quantity of light per unit area on a surface. The unit of illuminance is lux and abbreviated as lx.

Abbreviation is used after numerical expression, just like in lumens and Candela terms. For example; 100 lx, 1.000 lx, 10.000 lx.

1 lux is equal to 1 lumen per square meter. 1 candela light intensity provides 1 lux light level in 1-meter distance.

Illumination of an environment is expressed with lux value. Higher lux value means higher illuminance. However, it should not be forgotten that excess lighting does not mean good lighting. Excessive lighting has also negative effect like insufficient lighting.

If we mention about the proper common illuminance; in a sunny day 10.000 lux, in a cloudy day 1.000 lux, sunset 10 lux, in a moonlight 0,1 lux illuminance can be seen.

Lux value is related to lumen which expressed the total light output of a light source. As you move away from the light source, lux value decreased.

If the light concentrated on a small area, this area perceived as brighter and reached to high lux value. However, the same amount of light concentrated on a wider area, more soft light occurred and has less lux value measured. Although both light sources emitted same amount of light, in the concentrated light source, it is perceived as brighter because the light is more intense.

In general, lux is the measure of the intensity of light that reaches an area.

If lighting equipment with high light output in other words high lumen value is used in an area, high level of illumination is obtained. This means high lux level is obtained.

The level of illumination or lux value in an environment is measured by devices called lux meter. These devices only measure illuminance and they are designed as portable. Also, these devices are not so expensive.

For example, in the office, 500 lux lighting is required and 100 lux lighting is sufficient in the living room. In areas like drawing offices, textile mills and laboratories require high light levels such as 1.000 lux. At this point, updated lighting requirements should be reviewed according to the type of application.