Monthly Archives: January 2022

Tero Explains: What is EPREL for light sources? 2/3

The first article of this 3-part blog post series was dealing with the near-term history of European directives and regulations related to energy efficiency and different energy-related products (ErP), not only energy-using products (EuP).

Starting from Kioto 2005, this process has then proceeded to the situation, where new kinds of regulations have been taken into use, concerning many energy-related products, the latest of those being light sources.

Since 1st September 2021, the insertion of light sources into the EPREL (European Product Registry for Energy Labelling) database has been possible officially. Some problems have occurred in the technical insertion process and also in decisions over which component is a light source and which component is not. The term ’light source’ is defined in the European Commission Regulation EU 2019/2020 laying down ecodesign requirements for light sources and separate control gears (Single Lighting Regulation, SLR).

In this blog post, you can learn how light sources are categorized and what this categorization means in each case.

Categorizing the light sources – is the light source removable or not?

I shortly presented the terms of ’containing product’, ’light source’, and ’separate control gear’ in my earlier blog post in this series. SLR requires that the light source and separate control gear are removable so that the luminaire/fixture can be called the containing product. If not removable, the whole fixture itself has to be regarded as a light source.

Here starts the categorization. I concentrate on light sources in this post. The easiest case is a containing product without a light source: Not Applicable (it is just an empty luminaire body that has no light source included). The second easiest case is the LED lamp that you can buy from a retail store. Then it is not containing a product but only a light source. The sales package in store should include an energy label and other information defined in SLR regulation. Additionally, the lamp information should be added to the EPREL database.

Then let’s proceed into the case(s) where containing product includes the light source.

The first question is that is the light source itself removable? If it is, then it has to fulfill light source requirements defined in Ecodesign/SLR regulation. It is enough that the light source is removable from the containing product without breaking the light source. The containing product is allowed to still deteriorate in that case, but not the light source.

Then there is the next case. If the light source is NOT removable without breaking it, then the whole lighting fixture is considered a light source. The sales package of the containing product has to include an energy label and also other information defined in SLR regulation.

So, the key point is the question, is the light source removable or not? The question, is the light source replaceable or not, is not relevant otherwise than for the end-user that is you or me, a consumer. The supplier (or manufacturer) has to inform in their technical representation, why the light source is not replaceable. This technical documentation should also include information that “this containing product includes a light source the energy efficiency class of which is X”. X can vary from A to G in the new energy efficiency classification. Light source information together with the energy efficiency class must be found in the EPREL database.

Requirements defined in SLR/Ecodesign Regulation

There are several requirements defined in SLR/Ecodesign regulation. These are:

  1. Energy efficiency requirements
  2. Functional requirements
  3. Information requirements (markings)

Energy efficiency requirements

First of all, energy efficiency requirements demand that power consumption of a light source can’t exceed Pon,max (W), which is defined for different light sources in the 2019/2020 SLR regulation. Pon,max depends on many parameters, some of them are real and measurable values and part of them are computational values or factors/multipliers. Computational values are based somewhat ”loosely” on the real world.

If you measure for example your LED board/module in the integrating sphere, and the light source is defined as a non-directional light source (NDLS), you can use all lumens that you measure in your sphere as useful luminous flux (term defined in SLR regulation). If you have a directional light source (DLS), the regulation defines which portion of light you can use for this directional light source. Usually, the measurement for the DLS light sources is better to carry out with a goniometer that can measure light intensity at different angles unlike with integrating sphere which collects all the light rays and integrates them for the spectrometer through an optical fiber.

This relates essentially to EPREL energy class information because you define the energy class according to the following equation:

hTM = (Fuse/Pon) x FTM

where hTM is total mains efficacy, Fuse and Pon are LED parameters (useful luminous flux and power consumption of the measured LED board, COB LED, or any other light source) that are measured from the light source and FTM is a multiplier that is 1.00 for mains light source (MLS, e.g. AC LED) and 0.926 for the non-mains light source (NMLS, e.g. LED board that needs a separate control gear for operation).

The updated measurement software can calculate hTM value directly when you first choose in the software, is your light source NDLS or DLS, and is it NMLS or MLS light source. So spectrometer first measures luminous flux and power consumption and calculates LED luminous efficacy, and then by using a correct multiplier for your light source, calculates total mains efficacy that defines the energy class. For example, in the case of an LED board with separate control gear, this multiplier is 0.926 (see the previous paragraph). Then you can add your LED light source to the EPREL database by filling in all public information, and the EPREL database creates the final energy label for your light source. For market surveillance, you have to add also other technical information, that is not publicly available for everyone.

Functional requirements

Then there are functional requirements. They include many parameters that also depend on the used control gear (LED driver in our case).

  • CRI index ≥80 (outdoor and industrial applications are the exceptions)
  • Power factor cosf (certain limits, depending on the control gear used)
  • Lumen maintenance factor (LED and OLED light sources) àbased on L70B50 value in hours
  • Survival factor (LED and OLED light sources) àrelated to the lumen maintenance factor
  • Color consistency (LED and OLED) àhas to be MacAdam 6-step or lower
  • Flicker PstLM (LED and OLED), depends on the control gear à PstLM≤1.0
  • Stroboscopic effect (LED and OLED), depending on the control gear à SVM value≤0.4

Two last values are defined at full load condition.

Information requirements (markings)

Finally, there are information (marking) requirements.

The surface of the light source itself (not package marking):

  • Useful luminous flux (lm)
  • CCT/Correlated color temperature (K)
  • For directional light sources (DLS), also radiation angle (°)
  • Depending on the size of the light source, the priority is 1) Luminous flux, 2) CCT and 3) radiation angle.

Packing information:

For all light sources, which are sold separately in an independent packaging (but not in a containing product) through a point-of-sale, there are several requirements regarding the packing information. Some of these are mentioned below. It is to be noted that the three first ones shall also be marked on the surface of the light source, given that there is space for all three.

  • Useful luminous flux (lm)
  • CCT/Correlated color temperature (K)
  • For directional light sources (DLS), radiation angle (°)
  • Electrical interface details
  • L70B50 lifetime (hours)
  • On-mode power (Pon)
  • Standby power (Psb)
  • Networked standby power (Pnet)
  • CRI/Colour rendering index
  • Indication if CRI<80 (note; the application must allow it)
  • Indication if the light source is designed for non-standard conditions
  • Warning sign, if dimming is not allowed or can be realized only with specific dimmers
  • Warning sign, if the light source contains mercury

As an alternative to text, the information can also be given in the form of graphs, drawings, or symbols. Besides this information, the packing must show the energy label.

If a light source is being sold as a part of containing the product (and the light source is removable), the requirements are different. In this case, there can’t be any energy label on the containing product packaging. The packaging must indicate the following:

  • Information on whether the light source is replaceable or not, must be shown on the packaging (in the case of end-user sales) or on a free-access website
  • Information if the light source can be replaced only by a professional

As an alternative to text, the information can also be given in the form of graphs, drawings, or symbols.


This is what SLR is in a nutshell. And how you define energy class for your light sources. For printing the label from the EPREL database, you can ask help from the EPREL help desk or your local officials.

In the third, and the last, article of this blog post series, we concentrate on the effects that these regulations may set for the whole lighting industry. As you can see, many parameters depend also on the driver/control gear that is used with the light source. How this affects the component (light source and/or control gear) selections to make genuinely Eco-designed containing products, this we will discuss in the last part of this series.

If you have any questions, you can email me at