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Basic parameters used in lighting you should know

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Basic parameters used in lighting
Basic parameters used in lighting

Luminous flux

Luminous flux

Abbreviation:φphi
Unit:lmlumen

The luminous flux describes the quantity of light emitted by a light source. The luminous efficiency  is the ratio of the luminous  flux to the electrical power consumed (lm/W). It is a measure of a lamp’s  economic efficiency.


Luminous intensity

Luminous intensity

Abbreviation:I
Unit:cdcandela

The luminous intensity describes the quantity of light that is radiated in a particular direction. This is a useful measurement for directive lighting elements such as reflectors. It is represented by the luminous intensity distribution curve (LDC).


Illuminance

Illuminance

Abbreviation:Ephi
Unit:lxlux

Illuminance describes the quantity of luminous flux falling on a surface. It decreases by the square of the distance (inverse square law). Relevant standards specify the required illuminance (e.g. EN 12464 “Lighting of indoor work-places”).

Illuminance:
E(lx) = luminous flux (lm) / area (m2)


Luminance

Luminance

Abbreviation:L
Unit:cd/m2

The luminance is the only basic lighting parameter that  is perceived by the eye. It specifies the brightness of  a surface and is essentially dependent on its reflectance (finish and colour).

SOURCE: Zumtobel Staff – The Lighting Book

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Edvard Csanyi

Edvard - Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV/MV switchgears and LV high power busbar trunking (<6300A) in power substations, commercial buildings and industry fascilities. Professional in AutoCAD programming. Present on