What is LENI? (Lighting Energy Numeric Indicator)

LENI (European Standard EN 15193-1) is a way of giving a number to the energy consumption for lighting in a building.

These blog pages are not a tutorial on LENI, but some help I hope to people using search engines to find out more information on the standard. Anyway...

 Summarizing, very roughly:

The bigger the number the worse the value is, it means more energy is being used for lighting. So:

1. Low LENI = Good
2. High LENI = Bad

Now a bit more detail about the W in the above formula:

Now if we look at WL,t closer:

We are starting to go down the rabbit hole which is the complex arrangement of nested formulas in LENI. I'll be explaining the other terms over the next few blog posts.

To finish this post though here are some definitions of the various "types" of "LENI":

·	LENI = Annual LENI of the whole  building, the most important.

·	sub-LENI = Annual LENI of a particular floor, room, or zone. It and gives details of the consumption within the building areas

·

Specific Energy = Energy divided by area per month (or maybe even day hour) of the building, floor, room, or zone. That said LENI (= Annual LENI) is the most important one.  Here is a more detailed look  at some of those formulas. LeniCalc, a program to do the calculation for you!