What is mean by light efficiency < 17 Ln/W , What stands for Ln/W?

Question

What is mean by light efficiency < 17 Ln/W , What stands for Ln/W?

Answer 1

Overall luminous efficacy (lm/W)

In SI, luminous efficacy has units of lumens per watt (lm/W).

*efficiency is a dimension less unit.

pl. read below:

&quot;Artificial light sources are usually evaluated in terms of a related quantity, the overall luminous efficacy. This is the ratio between the total luminous flux emitted by a device and the total amount of input power (electrical, etc.) it consumes. This is often simply called “luminous efficacy”, which can be confusing as it also has units of lm/W. It is also sometimes referred to as the wall-plug luminous efficacy or simply wall-plug efficacy. The overall luminous efficacy is a measure of the efficiency of the device with the output adjusted to account for the spectral response curve (the “luminosity function”). When expressed in dimensionless form (for example, as a fraction of the maximum possible luminous efficacy), this value may be called overall luminous efficiency, wall-plug luminous efficiency, or simply the lighting efficiency.

The main difference between the regular and “overall” efficacies is that the latter account for input energy that is lost as heat or otherwise exits the source as something other than electromagnetic radiation. True luminous efficacy is a property of the radiation emitted by a source. Overall luminous efficacy is a property of the source as a whole.&quot;

Answer 2

It tells you how much light (maybe Lumens or candelas) for the electricity (Watts)