LENI Control Systems vs LENI Control Techniques

LENI is so complicated it can be easy to confuse control systems with control techniques.

Control Systems (in LENI terminology) are illustrated by this graph:

There are four of them and they are to do with how (intelligent sensor controlled) lighting reacts to the presence and absence of (forgetful) people. 

Fo, occupancy, is a measure of whether the room is occupied or not in a given time period. 

Fo = 1 if the lights are controlled centrally and the controller (human or automatic) does not know or care whether the rooms are occupied or not.

Fo < 1 if the room lights are switched on and off according to whether the room is in use or not. Again it could be a manual human control system (on off switch) or an automatic presence detecting system.

You'd think that...

Fa = 1 - Fo

...and that is true for Manual On/Auto Off, but not for any of the other three. I can only imagine that the curve for Manual On/Auto Off is the best one. A person enters the room, switches on the light, and even if s/he is forgetful, the automatic system will switch off the lights when the person leaves.

The manual on/off switch presumably takes into account the fact that lights can be left on by mistake when a persons leaves and the room becomes empty.

Here's my own personal idea about the graph:

So that was the Control Systems (Occupancy Control Systems would be a better name).

Then there are Control Techniques, there are eight of them, and specify how (intelligent sensor controlled) lighting reacts to the daylight supply of the room. To give them their full name they are Daylight-Responsive Control Techniques. They are summarized in this table:

 

This table needs some explanation. It is a look-up table, given three parameters you can lookup the output. The output is Fdc, used to calculate the Daylight Dependency Factor. 

The first input is type of control, which is basically the first four columns in the above table. There are eight of them (from I to VIII).

The second input is daylight availability, as a simple choice between three options, Low Medium and Strong.

The third input is lux required, maintained illuminance, as an option between 300lx, 500lx and 750lx.

 

Summarizing:

 

...and the output from the table lookup is used in the formula for Fd... 

AD and non AD areas in a LENI calculation

Since I've fallen into this trap myself I thought I'd warn you others out there about the difference between AD and AND zones in a LENI calculation.

In a zone an AD area is an Area illuminated by Daylight. In other words the horizontal rectangle attached to the vertical window which models the area illuminated by light coming through the window from outside.

So here is a simple room with two windows and their AD rectangles in pink:

The size of the rectangles (based on the size of the window generating the area) is explained in the EN 15193-1 standard itself.

The AND (Area No Daylight) is everything in the room which is not in a window's AD area, so the dark green shown below:

The trap that I sometimes fall into is I put lighting products which respond to daylight in areas which do not receive daylight! 

Here's the same room in plan view, with lighting products in AD and AND areas:

The image above illustrates how the LENI standard evaluates the energy consumption of luminaires based not only on their intrinsic consumption, but also whether they are placed in an area affected by daylight or not.

Note that putting any luminaire in a window zone will, according to the standard, reduce its consumption somewhat.

LENICALC Windows program for the EN 15193-1 standard

 

LENICALC is a program which does all the EN-15193-1 calculations for you, as long as you have all the right data of course. Click on the LENICALC icon on the download page:

Download LENICALC

It is free and runs on any 64 bit Windows operating system from Windows 7 and upwards.

I strongly advise that you read and do the two tutorials in this online help file before you start creating your own LeniCalc project.

Note when you install the program you'll get the Windows help file with the same tutorials, but it may be that the online version gets updated more often.