Transcript B 4b lumen method

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 RSMF
E =Maintained illuminance, lux
A = 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
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(Taken from Table 3.5 and 3.6 of
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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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