Basic parameters used in lighting
Basic parameters used in lighting

Luminous flux

Luminous flux


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


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 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”).

E(lx) = luminous flux (lm) / area (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 high power busbar trunking (<6300A) in power substations, buildings and industry fascilities. Designing of LV/MV switchgears.Professional in AutoCAD programming and web-design.Present on


  1. Albert simiyu
    May 11, 2015

    explain the technology how the quantity of natural lights controls the quantity of illumination of the building?

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  3. tabokhadra
    Sep 25, 2012

    you should add UGR AND GLARE

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