About light and illumination

About light and illumination

About light and illumination



  • Absorption

    The term absorption refers quite generally to the absorption of light. When light strikes a surface, it is absorbed to differing extents depending on the material, colour and frequency. The light loses energy as it penetrates material; it can only propagate without hindrance in a pure vacuum. Absorption is thus the capacity of materials to absorb light and neither to reflect nor to transmit it.

  • Accent lighting

    If individual room areas or objects are emphasised by light, we talk of accent lighting. Accent lighting comes into its own when its luminous intensity significantly exceeds the level of general illumination. This opens up countless possibilities for designing light that uses different degrees of illuminance, contrasts, shadows and incident light scenarios.

  • Adaptation

    The adjustment process in which the eye becomes accustomed in time to the change in brightness is called adaptation. The luminance levels at the beginning and end of the change in brightness influence the adaptation process and thus the adaptation time. While adaptation from dark to light takes only seconds, the eyes need minutes to adjust from light to dark. Visual performance is determined by the level of adaptation.

  • Adaptive illumination

    Adaptive illumination or dynamic illumination automatically adapts to the lighting conditions during the course of the day. The intensity, colour and direction of artificial light are changeable parameters. This technology is used in commercial environments in particular. For example, staff working in open plan offices or industrial facilities get a sense of the time of day and light deficits are compensated. The simulated daylight curve can be defined according to the time of day or geared to measured values recorded by sensors.

  • Area of the visual task

    The area of the visual task is the part of the working area in which the actual visual task is performed. The values specified in DIN EN 12464-1 for the illumination values apply exactly for this area. The surrounding area can be illuminated one level lower.


  • Basic illumination

    see General illumination

  • Beam angle

    The entire opening angle of the emitted light of a luminaire is called the beam angle. This in turn is determined by the design of the reflector. The narrower the beam angle of the reflector, the smaller and thus the brighter the illuminated surface becomes.

  • Binning

    By binning we mean a process in the industrial production of LED chips, in particular white chips. Within different production batches, differences in the lighting properties occur. For example, colour and luminosity may vary. To ensure that constant light quality with the same brightness level and uniform light colour is guaranteed, the LED from one batch must be sorted. They are sorted and placed in bins.


  • Candela

    Candela [ cd ] stands for the unit of luminous intensity, that is, the luminous flux per solid angle unit.
    It is usually given for directed light, for example with downlights, and serves to calculate the degree of illuminance of a surface in relation to angle and distance.

  • CE mark

    It is the responsibility of the manufacturer to make sure that his own products or their packaging has the “CE” (Conseil de l’Europe) mark. For the authorities responsible for monitoring these EU directives, it serves to document the fact that these products meet the requirements of certain directives of the European Union.
    However, the CE symbol is not a safety mark like the VDE symbol, ENEC symbol or GS mark. A product marked only with the CE symbol has therefore not been tested by a recognised inspection body.

  • Circadian rhythm

    If we talk of a person’s “biological clock”, we mean their circadian rhythm. Light has a chronobiological effect on the human rhythm, which it influences and synchronises. This rhythm is controlled by the change between day and night and the change in the seasons, and regulates active as well as passive phases. For example, a special receptor in the retina of the eye activates the sleep hormone melatonin.

  • Colour rendering

    The effect that the light of a lamp has on coloured objects or persons is specified by colour rendering and is evaluated with the general colour rendering index (CRI). The index, which is derived from eight common test colours, indicates how naturally colours are rendered in the light of a lamp.

    Here, CRI = 100 stands for the best value; the lower the index, the poorer the colour rendering properties. Lamps with a colour rendering index lower than 80 should not be used in interiors where people work or stay for longer periods.

  • Colour space

    Colour space stands for the three-dimensional representation of all colours of a colour model that can actually be emitted using a chromophoric method. Each chromophoric method has its own colour space. The body of colour is the representation of all colour spaces of a colour model.

  • Colour temperature

    The colour temperature is the light colour of a lamp and is measured in Kelvin ( K ). Common lamps have a colour temperature of the following order:

    • below 3300 Kelvin = warm white
    • 3300 to 5300 Kelvin = neutral white
    • more than 5300 Kelvin = daylight white

  • Connected wattage of the illumination

    The maximum output of the entire light installation in a room is described as the connected wattage of the illumination. It is independent of energy consumption.

  • Cut-off angle

    In the case of luminaires that emit direct light with an unfavourable cut-off angle, there is a risk of direct glare due to excessively high luminance values. To avoid this, luminaires are equipped with housing parts, slats or louvres that shield the light sources. High luminance values can also be reduced by means of opal or prismatic front covers. According to DIN EN 12665, the cut-off angle of a luminaire is the angle between the downwards directed vertical axis and the direction from which the lamp and the high-luminance surfaces are not yet visible (DIN EN 12665).
    The “Lighting of indoor work places” defines the cut-off angle as the corresponding angle with respect to the horizontal plane (DIN EN 12464-1).

  • Cylindrical illuminance Ez

    The minimum or maintained illuminance level of Ez is 50 lx. In areas where good visual communication is important, for example in offices or in conference rooms and classrooms, the maintained illuminance should be raised to 150 lx. In room and working areas, this requirement applies at a height of 1.2 m for sitting persons and 1.6 m for standing persons. In both cases, the required uniformity is above 0.10.


  • DALI

    DALI (Digital Addressable Lighting Interface) defines standardised digital device interfaces and is intended to guarantee the interchangeability of various operating devices in a lighting system.
    DALI requires two control cables, to which up to 64 DALI-compatible luminaires can be connected. These luminaires can be grouped into a maximum of 16 groups. DALI enables the light colour and light intensity to be controlled; light can also be switched based on time settings and sensors.

  • Degradation

    In lighting technology, the term degradation describes the drop in the luminous flux of LED. As a rule, this process is extremely slow and only becomes noticeable in LED after about 50 000 operating hours. Degradation is taken into account in the specification of the average service life for LED. After this period, the LED continue to emit light, but their luminous power drops.

  • Degree of illuminance

    The degree of illuminance E is the quotient of luminous flux and illuminated surface. It is measured horizontally and vertically in the unit lux ( lx ).

    For a plane surface, the following applies: E = φ / A

    The degree of illuminance specifies the luminous flux which strikes a certain surface from the light source.Horizontal and vertical illuminance: Eh and Ev

  • Degree of reflection

    The degree of reflection specifies, in percent, how much of the luminous flux striking a surface is reflected. Light surfaces reflect light more than dark surfaces. For example, a white wall has a degree of reflection of 85% and a dark red brick wall only 10%.

  • Degree of semi-cylindrical illuminance

    The degree of semi-cylindrical illuminance (Ehz) is measured in lux and describes the components of vertical illuminance that fall on a semi-cylindrical measuring surface. It ensures the improved recognition of approaching persons; in car parks, for example, approximately 1.5 to 5 lx should be measured about 1.5 m above the ground.

  • Device Type 8 (DT8) colour control

    Colour-controllable luminaires with DALI Device Type 8 (DT8) standard have two to six colour channels. Colour temperatures, colours and the light intensity can be adjusted. DT8 luminaires operate on multiple channels, but are only assigned one DALI address.

  • Direct/indirect illumination

    When direct and indirect illumination are mixed, the illumination is usually felt to be pleasant. In one room, luminaires emitting direct light and luminaires with only indirect light emission may be used together, or luminaires that combine both types of light emission. The indirect light is directed towards the wall or the ceiling, while additional light emission downwards provides direct light. The indirect light component has good reflective properties and higher light output.

  • Dispersion

    Dispersion refers to the property of a material where incident light is split into its wavelengths.

  • DMX

    DMX is the abbreviation for “Digital Multiplex” and is a transmission protocol for controlling lighting systems. The term comes from stage technology, and allows the highly flexible use of time and space-specific effects.
    In architectural lighting, DMX is used for particularly critical lighting scenarios with high dynamism levels, because it can be used specifically to control RGB colour mixing. Like DALI technology, this is a digital, addressable protocol, and can be connected to the DALI bus and KNX technology using gateway components.


  • Emergency lighting

    Emergency lighting stands for light sources that function independently of the power grid. In the event of power failures, escape routes are illuminated in such a way that people can find their way out of the building as quickly as possible and reach a safe place. Emergency and safety lighting is required by law in certain areas.

  • ENEC

    The European safety mark for luminaires and other electrical products is ENEC (European Norm Electrical Certification). It is awarded by neutral inspection and certification institutes in Europe, for example by VDE in Germany.

    The inspection body number “10” beside the ENEC symbol stands for VDE. ENEC+ is used to mark LED modules and LED-based luminaires.

  • Energy label

    The European Union (EU) has defined energy efficiency classes for light sources, which apply throughout Europe. The classifications range from A++ for very energy-efficient down to E, the poorest efficiency rating. LED usually achieve an energy efficiency class rating of A++ or A+.


    EULUMDAT is a file format which describes the intensity distribution of light sources. The file extension for this photometric data is *.ldt. In Europe, this file format has been an established industrial standard for the transmission of photometric data since 1990. In America, the format IES is used parallel to the European standards.


  • Gateway

    Connections between different systems are referred to as gateways. A gateway is the interface between different communication protocols. In lighting technology, for example, an LCN line can be connected to a DALI line via a gateway. An LCN/DALI gateway lets you integrate up to 64 luminaires with DALI operating devices in an LCN system. With the BEGA Control software, you can configure DALI groups and DALI lighting scenarios, and can assign the control module outputs.

  • General illumination

    General illumination defines the environment and clarifies room situations. The light should be uniformly distributed and should not create any harsh shadows. This ensures quick orientation in architectural environments.

  • Glare

    Glare radiates directly from the lamp or indirectly from reflections on shiny surfaces, and is unpleasant and irritating for the eye. It can be stronger or weaker, depending on the luminance and size of the light source, its position in relation to the viewer, the brightness of the surroundings and of the background. Even if it cannot be avoided completely, glare can be reduced by the correct arrangement and shielding of the luminaires as well as with the right choice of colour and structure of the room surface. In particular it is important to avoid direct glare in road lighting so as not to jeopardise road safety. In the planning of computer workplaces, the prevention of reflected glare is of particular importance.

  • GRL

    According to the CIE glare rating process, GRL is the upper limit value for glare.
    In outdoor lighting systems, glare generated directly by luminaires is determined according to the CIE glare rating (GR) method.

  • GS mark

    The GS Mark stands for “Geprüfte Sicherheit” (tested safety) and confirms conformity with the German Equipment Safety Act. It is only used in conjunction with the mark of the inspection body, such as TÜV or VDE.


  • Half beam angle

    The half beam angle is also called beam angle, half-value angle or opening angle.
    It is the beam angle used most frequently in lighting technology and is therefore also frequently specified by the manufacturers. The half beam angle describes the metrologically relevant range of radiation and thus defines an abstract limit which the human eye cannot perceive. It is the angle between two points at which the luminous intensity falls to 50% of the maximum value. The diameter of a light cone is also given with the help of the half beam angle.

  • Human centric lighting

    Daylight defines the rhythm of human life. Physiological processes such as the sleep-wake rhythm regulated by hormones, general well-being, and concentration and performance are dependent on sunlight. Since many activities are performed indoors, artificial light should emulate missing sunlight accordingly; it should also be possible to adapt this light to human needs. This supports circadian processes in the body. Stimulating or relaxing light can be used as required.


  • Illumination classes

    There are three types of illumination classes – pre-classification into M, P and C classes is based on the traffic situation and composition of traffic. Within these classes, further selection is based on additional parameters, such as the traffic volume, speed, the difficulty of the driving task, etc.

    M classes:
    Mainly roads with motorised traffic, such as main roads and thoroughfares. Evaluation is based on the luminance method taking the road surface into consideration. In addition to the average illumination density, the overall and longitudinal uniformity are used as quality characteristics, as well as the environment illuminance ratio REI and the glare percentage value fTI .

    P classes:
    Roads with a low volume of traffic and low speeds, as well as areas for pedestrians and/or cyclists. Evaluation is based on the average and minimum degree of illuminance.

    C classes:
    Conflict zones, such as areas where the flow of traffic is split, intersections and junctions. These also include roundabouts and pedestrian crossings. Evaluation is based on the average degree of illuminance and uniformity.

  • Illumination level

    The illumination level describes the average degree of illuminance in a room. It depends not only on the degree of illuminance but also on the reflective properties of the room surface.


  • LCN

    LCN technology is a control system, to be more precise a building automation bus, in which the modules behave cooperatively and are organised decentrally. Each module can be parameterised individually and permanently for control tasks. Its main advantages are its range, its immunity to interference and its fast response times.

  • LED

    LED is the abbreviation for light-emitting diodes. LED are electronic semiconductor components which emit light in the colours red, yellow, green or blue when power is applied. LED emitting blue light can also generate white light with the help of an additional internal luminous coating. White light can also be generated by colour mixing. The advantages of LED are freedom from maintenance, a long service life, low energy consumption, freedom from IR/UV light, colour stability and insensitivity to vibrations. LED are available in different designs.

  • Light colour

    The light colour of a lamp is described by the colour temperature in Kelvin [K], see Colour temperatures.

  • Light control

    Light control makes it possible to coordinate illumination to the requirements and applications in question. Various switching and dimming states can be saved as light scenarios in the appropriate control devices and used again as required.
    Individual luminaires, a group of luminaires in a room, the entire lighting system in a building or the illumination of whole streets can be integrated in a light control system.

  • Light distribution

    The term light distribution refers to the spatial distribution of luminous intensity. The form and symmetry of the light distribution is determined by luminaires emitting symmetrical and asymmetrical or downwards-directed and wide-beam light. This is illustrated by the light distribution curve (LVK): This is created when the luminous intensities of a luminaire, shown in polar coordinates, are connected with each other in their various radiation directions to form a curved line.

  • Light immission

    Irritating light that is caused by incorrectly positioned or incorrectly adjusted luminaires is described as light immission. In the rooms of building stock adjacent to a lighting system, undesired and irritating illumination or even glare may occur. To avoid this, the German Lighting Society has published appropriate measuring and evaluation methods.

  • Light point

    In outdoor lighting, particularly in road lighting, individual luminaires are called light points.

  • Light point spacing

    A further designation in outdoor and/or road lighting is light point spacing. This describes the spacing between individual luminaires.

  • Light sensor

    Light sensors measure the brightness of daylight or artificial light. Light sensors are integrated in twilight switches and in other light control and light regulation systems.

  • Lumen

    The unit for luminous flux is lumen [ lm ], which measures the output emitted by the lamp in all directions in the visible spectrum.

  • Luminaire efficiency

    The relationship between the luminous flux of the luminaire and the luminous flux of the lamps used, which is determined under standardised operating conditions, is described as luminaire efficiency.

  • Luminance

    Luminance L is measured in luminous intensity (candela) per unit of area [cd/m²]. The impression of brightness that an illuminated or luminous surface makes on the eye is defined by luminance, just like the physiological effect of light on the eye.

  • Luminous efficiency

    Luminous efficiency defines the relationship between the luminous flux of a lamp and its electrical power consumption. It is expressed in lumen per watt ( lm/W ).

  • Luminous flux

    The light output of a lamp is its luminous flux φ. It is measured in lumen [ lm ]. An LED module of 10 W can reach up to about 1200 lm.

  • Luminous intensity

    Luminous intensity “I” is the component of luminous flux that radiates in a certain direction. The distribution of the luminous intensity of luminaires in a room is graphically illustrated as light distribution curves (LDC).

  • Lux

    The degree of illuminance is measured in lux [ lx ]. A luxmeter indicates how much luminous flux strikes a certain surface.


  • MacAdam ellipse

    In 1931, the CIE (Commission Internationale de l’Éclairage) developed the colour space system, a system to describe all colours that can be perceived by the human eye. Using an XY coordinate system, all visible colours are represented in a geometric figure. The colours with the highest saturation are located at the edge of the figure. The saturation decreases inwards.
    In the 1940s, David L. MacAdam examined how adjacent colours differed from a reference hue within the illustrated colour space. He defined colour points and investigated at what point the human eye recognised deviations from these fixed colours when moving away from the respective colour point in any direction. These areas were larger in the green colour space than for red and blue hues. The tolerance for colour deviations in green hues is therefore greater than that in red/blue hues. Originally it was assumed that these areas formed a circle around a reference hue. MacAdam disproved this assumption. The shape of these areas was nevertheless always the same – an ellipse.

  • Maintained illuminance

    Maintained illuminance figures for the degree of illuminance Ē and maintained illuminance figures for luminance -L result from the visual task in question. They are average figures for the lighting system below which the illumination must not fall at any time.
    Figures for the degree of illuminance for indoor illumination can be found in the standard DIN EN 12464-1. Corresponding specifications for “Outdoor work places” are set out in DIN EN 12464-2. DIN EN 13201-2 contains the values for the degree of illuminance or for the luminance of road lighting.The European standard DIN EN 12193 applies for sports lighting.

  • Maintenance factor MF

    The operating conditions and type of components used influence the maintenance factor MF of a lighting system. This defines to what degree a planned system must be over-dimensioned in order to still represent the standardized degree of illuminance at the time of maintenance. Excessive operating costs are avoided if over-dimensioning is as accurate as possible. On the other hand, if planning is under-dimensioned, the degree of illuminance falls below the minimum value.

  • Modelling

    Modelling is the process of defining and accentuating the environment using light. Only the combination of light and shade gives objects the necessary plasticity – enabling bodies, surfaces and structures to be detected visually.
    The way in which shadows are cast depends on the direction of light. This is determined by the light distribution of the luminaires and their arrangement in the room. Without shadows, rooms and objects appear almost two-dimensional. A balanced interplay between light and shade creates visual comfort and a pleasant lighting atmosphere.

  • Motion sensor

    A motion sensor is an electronic sensor which detects movement in its immediate proximity and operates as an electrical switch. It is primarily used to switch on illumination or to trigger an alarm. A motion sensor can operate actively depending on electromagnetic waves and ultrasound, or passively based on the infrared radiation in the environment – these aspects can also be combined.

    The pyroelectric sensor (PIR sensor) is the most commonly used type of motion sensor. It responds immediately to small changes in temperature, e.g. when someone moves in the range of the sensor. Motion sensors that use Doppler radar technology respond optimally when the distance from the sensor changes.

  • Mounting height

    The mounting height indicates from what height the light of the luminaire strikes the surface to be illuminated.


  • Nominal illuminance

    This term used to be used in the national illumination standards. It defines the average degree of illuminance in a furnished room, with reference to an average age condition. To determine the new value of a lighting system, the nominal illuminance was multiplied by the planning factor 1.25. Today, ageing and dirt accumulation in a lighting system are described with maintained illuminance.


  • Photometric distance law

    The degree of illuminance E decreases with the square of the distance r from a point-shaped light source.
    The result is as follows: E = I / r² (I = luminous intensity)

  • Point illuminance

    Point illuminance can be used to make a statement about the quality of the illumination at a certain point in a room. It is the quotient of the luminous flux which one point on a surface element receives and the area of the element.

  • Protection class

    For purposes of durability, luminaires must be designed mechanically in such a way that foreign bodies and damp cannot enter, as far as possible.
    The IP code number system “International Protection” is used to identify the protection class with two code numbers. The first code number after the IP (1 to 6) indicates the degree of protection against foreign bodies, while the second code number (1 to 8) stands for protection from water. The higher protection class always includes the lower class. If one of the two protection class code numbers is not shown, the luminaire must be marked “X” as untested.


  • Quality characteristics

    The illumination quality of artificial illumination is defined by quality characteristics. Among other things, the following quality characteristics must be evaluated: light colour, illumination level, glare limitation, trouble-free vision without direct or reflected glare, brightness and its harmonious distribution, the balanced relationship between luminance levels as well as the appearance of the lamps and their colour rendering.


  • Radiation characteristic

    The direction-dependent radiation of the light of a luminaire is called radiation characteristic. It can be influenced by shields, diffusers, louvres or reflectors and can be represented in luminous intensity distribution curves. Depending on the form of these curves, we distinguish between symmetrical, asymmetrical, flat beam, narrow beam and wide beam radiation characteristics.

  • Reduced lighting at night

    Reduced lighting of roads and paths at night is used to save energy during off-peak periods. For luminaires which only have one light source, the output of the individual light point is reduced. If a luminaire has several light sources, some of them are switched off. Both methods ensure that energy is saved while the illumination of roads and paths remains uniform, but at a lower intensity. As soon as sensors detect the presence of people or vehicles, the illumination level must be increased again in accordance with the standard.

  • Refraction

    The refraction of light in physics refers to the change in direction of wave propagation. Refraction is expressed by the “refractive index.” In lighting technology, light is refracted using lenses, for example.

  • RGB colour mixing

    The sequence of letters “RGB” is an abbreviation for the colour mixing of light using lamps in the primary colours of red, green and blue. This RGB colour mixing is particularly suitable for decorative illumination with colour dynamics. In order to obtain a better white light colour, it is possible to work with an additional white light source (RGB W colour mixing).


  • Safety class

    The safety class defines the type of protective measure against a possible electric shock:

    Safety class I
    Luminaires for connection to a line-side protective conductor. The symbol is applied at the connecting point.

    Safety class II
    Luminaires with additional or reinforced insulation. They have no protective conductor connection.

    Safety class III
    Luminaires for operation with safety extra low voltage.

  • Safety extra low voltage

    Safety extra low voltage is a low electrical voltage which offers special protection against electric shock due to its low level and isolation from circuits of higher voltage. The voltage is so low that there is usually no risk of electrical current flowing through the body. Luminaires must be designed specifically for operation with safety extra low voltage.

  • Spectral colours

    Light appears white, but is composed of different colours. The rainbow fans out these colours. They are referred to as spectral colours. The wavelengths of light that is visible for human beings range from 380 to 780 nanometres [nm].

  • Spectral radiation distribution

    Spectral radiation distribution describes the characteristics and intensity of electromagnetic waves in the wavelength range that is visible for human beings.
    Each wavelength of visible light has a certain spectral colour. In daylight, the intensity of all spectral colours is relatively homogeneous, whereby the blue components are somewhat predominant.
    The characteristics of the individual spectral colours can be illustrated visually by means of a system of coordinates, with the axes intensity and wavelength of light. This type of illustration is helpful for comparing lamps, for example.

  • Steradian

    The steradian (sr), also sterad, describes a unit for the solid angle. It is contained in the SI system of units as a derived unit.


  • Transmission

    In physics, transmission is the property of a material or body that allows sound waves or electromagnetic waves in the form of light to pass through it.
    Transmission refers to the effectiveness of this property. It indicates the ratio of transmitted luminous flux to incident luminous flux. Transmission is either directed or diffuse and describes the translucency of an object. The more translucent it is, the brighter it shines. The darker a medium is, the more light is absorbed.

  • Tunable white

    Tunable white enables the colour temperature of white light to be adjusted variably. The colour temperature can be set between 2700 K (warm white) and 6500 K (cold white) and allows the variability of white light to be utilised in specific ways. This significantly improves perception and light quality.


  • UGR

    The “Unified Glare Rating” (UGR) process was developed by the International Commission on Illumination CIE (Commission Internationale de l’Éclairage) to standardise the rating of glare worldwide.
    DIN EN 12464-1 specifies the UGR reference value for a standard room. Modern light planning programs allow the exact calculation of the UGR rating for a defined observer position in the room. The lower the UGR rating, the lower the glare. The elevation angle 65°, 75° or 85° is also specified for luminance levels < 1000 candela per square metre (relationship between luminous intensity and surface area). This is the critical angle above which the luminaire has a luminance of 1000 candela per square metre all round.

  • Uniformity

    Uniformity describes a further quality characteristic of the degree of illuminance or luminance. It is given as the ratio between the minimum and the average degree of illuminance g1 = Emin / Ē. In certain applications, the relationship between the minimum and the maximum degree of illuminance g2 = Emin / Emax plays a significant role.

    In road lighting, the relationship between the minimum and the average luminance of the degree of illuminance, or the luminance U0 = Lmin / -L as well as the relationship of longitudinal uniformity UL in the standard are decisive.


  • Visual comfort

    Visual comfort refers to the quality of illumination, in particular with respect to colour rendering and a harmonious distribution of light but also with respect to the well-being of the human eye.

  • Visual performance

    Visual performance is determined by the visual acuity of the eyes and the contrast sensitivity of the eyes for distinguishing between light and dark. Speed can also influence visual performance. When driving, for example, this can include differences in brightness, shapes, colours and details.

  • Visual task

    The visual task is determined by the light-dark and colour contrasts, as well as by the size of the details and the speeds and duration with which the contrasts are perceived. The illumination level must be adapted to the degree of difficulty of the visual task.


  • Wi-Fi

    Wi-Fi refers to a consortium of companies that certifies devices with radio interfaces and also to the associated brand name.
    The term Wi-Fi was coined for marketing purposes and was actually a pun on the word Hi-Fi. Whether or not the term represents an abbreviation, it’s clear that Wi means wireless.
    Wi-Fi is often used as a synonym for WLAN. Strictly speaking, WLAN and Wi-Fi are not the same thing. WLAN refers to the radio network, Wi-Fi on the other hand is the certification issued by the Wi-Fi Alliance based on the IEEE 802.11 standard – all Wi-Fi certified products are therefore 802.11-compliant.

  • Working plane

    The horizontal or vertical surface that is to be illuminated is called the working plane. Depending on the purpose of the illumination, the standards define a mathematical reference point at which the degree of illuminance is rated. This is usually 0.85 m above the ground.


  • Zigbee

    Zigbee is a standardised transmission protocol for wireless networks. Zigbee technology is used with control systems where there is no additional data or control cable. The implementation of third-party systems is possible. The Zigbee radio standard is characterised by its straightforward installation and application. It connects different network devices over short distances, which manage the network autonomously and communicate via the Zigbee protocol. Each device integrated in the network forwards radio signals to all available devices. This means that long distances, e.g. in the case of lighting systems, can be covered without any problem. The range between individual network points is up to 100 m. Energy efficiency is another performance feature of this radio standard.