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LUMEN METHOD

Utilization factor-- Ratio of flux received by reference plane to total rated lamp flux in the installation.Utilization factor of a lighting installation depends only on polar curve of the luminaire, the room geometry (represented by room index) and reflectances of the ceiling, wall and floor.

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Maintenance factor – -- LSF-- LLMF-- LMF-- RSMF

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LUMEN METHOD

E= N x n x ø x UF x MF A

where MF = LLMF x LSF x LMF x RSMFE =Maintained illuminance, luxA = Area, m2

Ø = Initial lamp flux, lumen

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LLMF & LSF

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(Taken from Table 3.4 of CIBSE Code for Lighting, 2002)

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LMF

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LMF

(Taken from Table 3.5 and 3.6 of CIBSE Code for Lighting, 2002)

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RSMF

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RSMF

(Taken from Table 3.7 of CIBSE Code for Lighting, 2002)

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