Sustainability in Action

LENI Calculations

Richard Garrett

LENI stands for Lighting Energy Numeric Indicator and enables an accurate calculation of the efficiency of an entire lighting installation. This includes the use of controls within a specific setting and is based on the required illuminance of a space as well as the number of luminaire operating hours per year.

The LENI methodology can be found in the current edition of EN 15193-1 and is also the lighting energy calculation method recommended in the building regulations guidance notes for the conservation of fuel & power in some countries – Building Regulation Part L, Volume 2 for Buildings Other Than Dwellings (England) and also in Austria & the Republic of Ireland

LENI looks at:

  • The predicted energy in use by the indoor and emergency lighting solutions as well as lighting control devices in place across an installation.
  • The total power consumption of the indoor lighting installation
  • Energy saved by the control system for predicted net lighting energy consumption for automatic occupancy detection, daylight linked electric lighting and constant illuminance control.