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On this page you can find the meanings of the most common lighting engineering and lighting design terms.

Luminous intensity
Intensity, or luminous intensity, describes the amount of light emitted in a particular direction. This is a useful measurement for directional lighting elements such as reflectors. It is represented by a light intensity distribution curve.

Unit: Candela (cd)
Landscape lighting
Landscape lighting includes the illumination of paths, small architectural forms, pools, fountains, plants. Basically, decorative lamps are used for landscape lighting, for example, ground lights, which perform the function of decorating the landscape and also functional lighting.
Architectural lighting
Architectural lighting is used to create the appearance of objects in the dark and it contributes to their memorability.

Main Types of Architectural Lighting

General lighting. It is mainly used for complete coverage of buildings and structures. The main goal is to create a holistic perception of the object. The powerful spotlights are used with general flood lighting, installing them on the ground or on nearby buildings. The outdoor lighting of this type is relevant for large architectural structures.

Local (zonal) or accent lighting of the facade. With its help, it is possible to highlight the main elements of architectural objects. It is realized with the help of LED facade lights of directional light.

Hidden artistic illumination. The uniqueness of architectural lighting of this type is that it is implemented using facade lamps hidden from the human eye. This approach allows specialists to implement projects of unprecedented beauty, transforming the facades of buildings and structures beyond recognition.

Silhouette or background lighting of architectural objects. It is used in cases where there is a need to highlight the contours of the structure. It is implemented by installing spotlights on the back of buildings.

Contour lighting of the facade. This type of architectural lighting is relevant where the definition of geometric shapes or building elements is appropriate. The linear LED luminaires are ideal for this purpose.

Dynamic colored lighting. The decorative (artistic) illumination of facades combines several effects at once that is a change in the intensity of the light flux, contrast and color. The dynamic lighting is created by using spotlights and lights of different types, controlled RGB and RGBW luminaires to create various dynamic lighting scenarios.

Decorative lighting. It is used to highlight individual elements of buildings: window openings, arches, bay windows. The decorative luminaires such as the RADUGA™ Eclipsis are typically low wattage and only serve to enhance lighting.
Accent lighting
Accent lighting is used to draw attention to individual interior details, elements of architecture or landscape. The directional light sources are used for accent lighting.

For example, architectural facade spotlights.
Combined lighting
Combined lighting uses direct and reflected light. This approach makes it possible to provide high efficiency and quality of light, to obtain good contrast, flexible layout of workplaces.
Indirect lighting
With indirect lighting, the light is directed to the ceiling and walls, only reflected light reaches the workplaces.

The advantages of reflected light: rooms seem higher, no glare and blinding effect, the location of workplaces is not tied to light sources.

The disadvantages of indirect lighting: lack of shadows can make objects appear flatter and blurry, lower energy efficiency.
Direct lighting
With direct or directional lighting, the light from the ceiling lights falls directly on the workplace. This type of lighting is provided by built-in or pendant lights and table lamps.

Advantages of direct lighting: high efficiency.

Possible disadvantages of direct lighting: dark ceiling (cave effect), the appearance of shadows on the work surface, glare.
Color reproduction
This is the ability of a light source to reproduce surface colors (8 test colors from R1 to R8) as accurately as possible compared to a reference light source. It is determined by the color rendering index (CRI). The best color rendering is 100.

CRI > 90 is a very good color rendering, CRI > 80 is a good color rendering.

To illuminate workplaces, it is recommended to choose light sources with a color rendering of at least 80. In industrial lighting, the choice of fixtures and color rendering depends on the nature of the work. If they are related to color vision, the equipment with a CRI > 90 is required.
Color temperature of light
A characteristic of the hue of white light that describes its visual perception. In a stricter definition, this is the blackbody temperature at which its color is the same as the color of the radiation of the light source under consideration (Reference Book on Lighting Engineering by Yu. B. Aizenberg). There are warm < 3300 K, neutral 3300 - 5000 K, and cold white > 5000 K.

Unit: Kelvin, K.
UGR Unified Glare Rating
The current regulation uses the Unified Glare Rating UGR. This is a pan-European criterion for assessing uncomfortable glare, which causes discomfort with an uneven distribution of brightness in the field of view. It is determined by the formula:


Light sources that are too bright in the field of view cause glare and make visual perception difficult. There are direct and indirect glare. The glare of light sources can cause a decrease in concentration and fatigue. To prevent these negative phenomena, light sources with reduced brightness or additional protection (hoods, gratings, etc.) are used. For example, the RADUGA™ Insolita luminaire is equipped with an anti-glare visor.
Brightness is the amount of light emitted per unit area. The only basic lighting parameter perceived by the eye. It describes, on the one hand, the impression of the brightness of the light source, and on the other hand, the surface, and therefore largely depends on the degree of reflection (color and surface).

It is measured in cd/m2 or Candela per square meter.
Illuminance describes the amount of light incident on the surface. The relevant standards determine the required illumination (for example, GOST R 55710-2013 National Standard of the Russian Federation "Lighting of indoor work places. Norms and methods of measuring"; SP 52.13330.2016 Code of Practice "Daylighting and artificial lighting". Updated edition of SNiP 23-05- 95. Illumination E (lx) = luminous flux (lm) / area (m²).

Unit: lux (lx)
Light intensity
Intensity, or luminous intensity, describes the amount of light emitted in a particular direction. This is a useful measurement for directional lighting elements such as reflectors. It is represented by a luminous intensity distribution curve.

Unit: Candela (cd)
Luminous efficiency
Luminous efficiency is the ratio of the luminous flux to the electrical power consumed. This is an indicator of the economic efficiency of the light source.

Unit: lm / W.
Luminous flux
Luminous flux describes the amount of light emitted by a light source for 1 second in the visible spectrum.

Unit: Lumen (lm)

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