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K. F. Chan (Mr.) ELEC 3105 1
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.
K. F. Chan (Mr.) ELEC 3105 3
LUMEN METHOD
E= N x n x ø x UF x MF
A
where MF = LLMF x LSF x LMF x RSMF
E =Maintained illuminance, lux
A = Area, m2
Ø = Initial lamp flux, lumen