Free Web Tool · IES Lumen Method

Lumen Method

Indoor lumen-method design — number of luminaires N for a target average illuminance Eav given room dimensions, CU, and LLF (lamp lumens, ballast factor, dirt depreciation).

Input

fixture above floor
between fixture & ceiling

Results

Room Cavity Ratio (RCR)
Light Loss Factor LLF
# fixtures N (calc)
Round to integer N
Resulting Eav
Method

RCR = 5 · h_rc · (L+W)/(L·W), where h_rc is fixture-to-workplane (H − hwp). LLF = BF · LLD · LDD · RSDD. N = (Eav · L · W) / (lampLm · lpf · CU · LLF). Round up.