Illumination intensity, Lux unit (lx)

What is illuminance?

Luminous intensity, also known as illumination, is a measure of the amount of light falling on a given surface. It is defined as the ratio of the luminous flux (Φ) to the surface area (S) on which that flux falls. It is expressed mathematically as Φ/S, where Φ is the luminous flux measured in lumens and S is the surface area in square metres. In SI units, illuminance is expressed in lux (lx).

It is the only quantity in photometry that describes not the properties of the light source itself, but the brightness with which an object or surface is illuminated. In other words, the luminous intensity determines how much light reaches a particular location. In practice, the higher the intensity, the better the surface is illuminated, which is important both in terms of visual comfort and the efficiency of working in a given environment.

Luminous intensity is the only quantity of light that does not characterise the light source itself, but the brightness of the illumination of a surface.

What is the unit of illuminance?

The unit of illuminance is lux (lx) equal to lumens per square meter (cd sr m-2)

The lux measures the amount of light falling on a surface and is the primary measure in assessing the brightness of lighting in a given location. One lux corresponds to the illuminance that is produced when one lumen of light flux is evenly distributed over an area of one square metre.

To better understand what a lux is, it is useful to know that a lumen (lm) is a unit of luminous flux, describing the amount of light emitted by a source. The lux takes into account not only the amount of light emitted, but also the surface area on which that light falls, which makes it possible to assess the actual brightness of illumination of a given space.

Lux is commonly used in various fields such as lighting design, architecture, photography, as well as in health and safety standards. For example, lighting standards may specify the minimum illuminance required for certain activities to ensure comfort and safety. A different one will be the recommended illuminance on a pavement, at a workstation, in an office or at home.

Through the use of lux, lighting levels can be accurately assessed and adapted to the needs of users, which is important in both public and private spaces. For example, illuminance standards for an office workstation range from 300 to 500 lux. In more precise activities, such as assembly work or laboratories, standards may require illuminance levels of as much as 1,000 lux or more to ensure accuracy and safety.

Luminous intensity is an important parameter in the design of both public and private spaces. That is why it is advisable to choose luminaires, from a proven lighting manufacturer. Our product range includes louvre luminaires, as well as solutions dedicated to investment lighting. Take a look at our full offer!

FAQ:

What is illumination intensity?

Luminous intensity, also known as illumination, is a measure of the amount of light falling on a given surface. It determines how brightly an object or surface is illuminated. Put simply, it shows how much light reaches a particular location.

How is illuminance calculated?

The illuminance is calculated as the ratio of the luminous flux (Φ) to the surface area (S) onto which this flux falls. Mathematically, this is expressed by the formula Φ/S, where Φ is the luminous flux measured in lumens and S is the surface area in square metres.

What is the unit of illuminance?

The SI unit of illuminance is the lux (lux). One lux corresponds to the illuminance when one lumen of light flux falls uniformly on an area of one square metre.

What is a lumen (lm)?

A lumen (lm) is a unit of luminous flux. It describes the total amount of light emitted by a light source.

What is the difference between lumens and lux?

The lux measures the total amount of light emitted by a source, while the lux also takes into account the surface onto which that light falls. The lux measures how brightly a surface is illuminated, while the lumen measures how much light the source itself emits.

What is the lux unit used for?

Lux is used in many areas such as:

Lighting design: For planning and optimising lighting in different spaces.
Architecture: For assessing and designing the lighting of buildings and their surroundings.
Photography: For setting exposures and lighting scenes.
Health and safety standards: For determining the minimum lighting levels required in workplaces.

What are examples of illuminance standards?

Example illuminance standards:

Office workstation: 300 to 500 lux.
Assembly work or laboratories: up to 1,000 lux or more.

Why choose light fittings from a proven manufacturer?

Choosing luminaires from a proven manufacturer ensures that the lighting parameters, including luminous intensity, are as declared. This ensures adequate and safe lighting, tailored to the needs of the space.

What is the illuminance formula?

The formula for illuminance is Φ/S, where:

Φ - luminous flux measured in lumens (lm)
S - area on which the light falls, measured in square metres (m²)

Does luminous intensity characterise the light source?

No, luminous intensity does not characterise the light source itself, but the brightness of the illumination of a surface. It describes how much light reaches a given area, not how much light is emitted by the source itself.

Illumination intensity, Lux unit (lx)

What is illuminance?

What is the unit of illuminance?

FAQ:

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