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(Pn fc) ((td fo fd) + (tn fo)) / A (1)
LENI = lighting energy numeric indicator (kWh/(m2 year))
Pn = installed load (kW)
fc = reducing factor due to use of daylight control (<1)
td = annual hours of use by day (h)
fo = reducing factor due to use of present based control (<1)
fd = reducing factor due to use of constant lighting maintenance control (<1)
tn = annual hours of use by night (h)
A = area (m2)
LENI is according to EN 15193 Energy performance of buildings – Energy requirements for lighting.
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