Non Directional & Directional Light Source

The NDLS and DLS are often seen in the new ErP EU2019/2015, Some people are confused about it, what are they? What they do, and how to distinguish them.

What are they?

The NDLS is short for Non-directional lighting source, which is the lighting source effective luminous flux within the 120°cone stereo angle is less than 80% of the light output of the entire luminaire, Conversely, it will be the DLS, which is short for Directional Light Source.

How to Distinguish them?

It defined the NDLS as lighting source effective luminous flux within the 120°cone stereo angle is less than 80% of the light output of the entire luminaire, so how to distinguish them means we can check the 120°Cone Stereo, but where can we find the 120°Cone Stereo? It usually appears on page 2 or page 4 of the PDF file of IES documents, 120°is the r angle of 50~60, and when the final %lum, is less than 80% it will be NDLS.

In some reports, the %lum, lamp data is shown directly at the bottom.

What do they do?

In the new ErP EU2019/2015, most of the suppliers tested the LED Modules only which shows the NDLS, in that way they can have a higher efficiency which is helpful for the Energy Efficiency Class, but the interesting thing is, most the home used light are DLS which has a super light control by optic lens or reflector which can take full use of the light to create a warm environment.