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Lighting Lumen Method
Number of luminaires for a target maintained illuminance by the CIBSE/SLL lumen method.
The Ensign ToolboxLighting Lumen MethodNumber of luminaires for a target maintained illuminance by the CIBSE/SLL lumen method.
Design target
lux
BS EN 12464-1 / LG7: 500 lux general office
m²
Luminaire
lm
Initial bare-lamp flux F. Set lamps = 1 to enter lumens per luminaire
no.
Lumen-method factors
ratio
Flux reaching the working plane (room index + reflectances). Typical 0.4–0.7
ratio
LLMF × LSF × LMF × RSMF. Typical 0.7–0.8 for clean LED
Enter the target illuminance, area, lamp flux and factors to size the lighting