LENI - Lighting Energy Numeric Indicator

The LENI - Lighting Energy Numeric Indicator - stands for the actual energy consumption of a lighting system in kWh per square metre and year - and can be calculated as

LENI = Σ(P_n f_c) ((t_d f_o f_d) + (t_n f_o)) / A                          (1)

where

LENI = lighting energy numeric indicator (kWh/(m² year))

P_n = installed load (kW)

f_c = reducing factor due to use of daylight control (<1)

t_d = annual hours of use by day (h) 

f_o = reducing factor due to use of present based control (<1)

f_d = reducing factor due to use of constant lighting maintenance control (<1)

t_n = annual hours of use by night (h) 

A = area (m²)        

LENI is according to EN 15193 Energy performance of buildings – Energy requirements for lighting.