How do you calculate lighting requirements using the lumen method?

The lumen method calculates required lumens: N = (E x A)/(F x CU x LLF), where E is target illuminance (lux), A is area (m2), F is lumens per fixture, CU is coefficient of utilization (typically 0.5-0.8), and LLF is light loss factor (0.7-0.9 accounting for depreciation). Room dimensions and reflectances determine CU from manufacturer tables. This method provides uniform spacing patterns. Point-by-point calculations may be needed for task lighting or irregular spaces.