Old vs. New EU Energy Label for Light Sources

7 min readApr 11, 2021

In March 2021 a new EU energy label was introduced. For lamps (light sources) it will be mandatory starting from September 1, 2021. In this article, we will take a look at what changed.

The purpose of this article is to give a rough overview of the differences between the energy label regulations. Read the full regulation to get the complete picture of the energy label-related regulations. Sources: EU Commission Delegated Regulations: Regulation from July 2012, Regulation from March 2019. Please note that this article is not legal advice and that this article simplifies the regulations to give a condensed overview. Please refer to the original regulations for the most accurate and legally binding information.

The old energy label ranged from A++ to E, the new label will range from A to G. It is mandatory for lamp producers to show the label on packages or in online shops for their lamps selling in the EU.

In this article we will focus on non-directional lamps meaning classic light bulb-type lamps radiating (almost) 360 degrees. Directional lamps are spots, for example, and focus the light beam to a certain area.

For simplification, we assume that no external control gear is required to operate the lamp (fluorescent lamps or high-intensity discharge lamps, for example, may require an external control gear). We will also assume that the lamp is operating on mains, which means that it is directly connected to AC.

Type of light source we are focusing on in this article. Photo by Federico Bottos on Unsplash

Prerequisites

Before we get into more details, we should clarify some terms and units.

Lumen (lm) is the unit of luminous flux, measuring the total quantity of visible light emitted by a source per time unit.

Watt (W) is a unit of power, quantifying the rate of energy transfer.

Kilowatt-hour (kWh) is a unit of energy. One kWh equals one kilowatt (1000 W) of power sustained for one hour.

Incandescent lamp: The classic light bulb where a wire filament is heated until it glows. Very inefficient in terms of energy consumption vs. light emission.

LED lamp: LED (light-emitting diode) lamps exist in many shapes and forms. When we refer to LED lamps in this article, we are referring to those resembling classic light bulbs (see image above). Very efficient in terms of energy consumption vs. light emission.

As mathematical symbols we use:

√ for square root
× for multiplication
/ for division

Old scale

2013 to 2021. (There were energy labels for device types other than light sources since 1995. In 2013 the energy label was introduced for light sources.)

The old energy label scale for light sources ranges from A++ (highest efficiency) to E (lowest efficiency).

The old scale was based on a lamp’s “Energy efficiency index” (EEI). The EEI is calculated as follows:

EEI = P-cor / P-ref

For calculating P-ref, we first need to know the lamp model’s useful luminous flux Φ-use in Lumen.

For models with Φ-use < 1300 Lumen: P-ref = 0,88 × √Φ-use + 0,049 × Φ-use
For models with Φ-use ≥ 1300 Lumen: P-ref = 0,07341 × Φ-use

As we simplify our calculations for this article by looking at classic light bulb-type lamps only (no external control gear), we can assume P-cor = P-rated. P-rated is the rated power of the lamp in Watt. For external control gears, we would have to apply a certain factor to P-rated to get P-cor.

Therefore, we can simplify the formula to:

If < 1300 Lumen: EEI = Watt / (0,88 × √Lumen + 0,049 × Lumen)
Otherwise: EEI = Watt / (0,07341 × Lumen)

The energy label A++ to E is assigned based on the EEI:

+-------+--------------------+
|  A++  | EEI ≤ 0,11         |
+-------+--------------------+
|  A+   | 0,11 < EEI ≤ 0,17  |
+-------+--------------------+
|  A    | 0,17 < EEI ≤ 0,24  |
+-------+--------------------+
|  B    | 0,24 < EEI ≤ 0,60  |
+-------+--------------------+
|  C    | 0,60 < EEI ≤ 0,80  |
+-------+--------------------+
|  D    | 0,80 < EEI ≤ 0,95  |
+-------+--------------------+
|  E    | EEI > 0,95         |
+-------+--------------------+

Now let’s look at three examples. The below table compares two LED lamps and one incandescent lamp (classic light bulb). Second row “eq.i.” shows the approximately equivalent incandescent lamp wattage of the light bulb with similar brightness because many readers are still more used to Watt than to Lumen for estimating the brightness of a lamp.

+-------+---------+--------+--------+
| Type  | LED     | LED    | incand.|
+-------+---------+--------+--------+
| eq.i. | 100 W   | 40 W   | 40 W   |
+-------+---------+--------+--------+
| P-cor | 11 W    | 4.5 W  | 40 W   |
+-------+---------+--------+--------+
| Φ-use | 1521 lm | 470 lm | 443 lm |
+-------+---------+--------+--------+
| P-ref | 111.7   | 42.1   | 40.2   |
+-------+---------+--------+--------+
| EEI   | 0,10    | 0.11   | 0.99   |
+-------+---------+--------+--------+
| Class | A++     | A++    | E      |
+-------+---------+--------+--------+

New scale

For light sources starting from September 2021.

The new energy label scale for light sources ranges from A (highest efficiency) to G (lowest efficiency). Even though there are seven categories just like in the old scale, it is not possible to directly map A++ from the old scale to A from the new scale, or A+ from the old scale to B from the new scale, etc.

The new scale is tailored more to currently available and future lamp types, so even A++ rated efficient LED lamps will be in lower categories in the new scale. As of 2021, it is not expected to see any lamps in category A (or B). Those are reserved for future lamps yet to be developed.

The new scale is based on a lamp’s “Total mains efficacy” (lm/W)

Compared to the old scale it’s easier to calculate:

ηTM = (Φ-use / P-on) × F-TM

ηTM stands for the total mains efficacy.

Φ-use is the useful luminous flux of the lamp model in Lumen.

P-on is the on-mode power consumption in Watt.

F-TM is a factor that depends on the lamp type (directional/non-directional, operating on mains/ not operating on mains). As we are looking at classic light bulb replacements within this article (non-directional, operating on mains), we can set F-TM to 1 which means we can ignore it for further calculations.

Therefore, we can simplify the formula to:

ηTM = Lumen / Watt

The energy label A to G is assigned based on ηTM:

+-----+------------------+
|  A  | 210 ≤ ηTM        |
+-----+------------------+
|  B  | 185 ≤ ηTM < 210  |
+-----+------------------+
|  C  | 160 ≤ ηTM < 185  |
+-----+------------------+
|  D  | 135 ≤ ηTM < 160  |
+-----+------------------+
|  E  | 110 ≤ ηTM < 135  |
+-----+------------------+
|  F  | 85 ≤ ηTM < 110   |
+-----+------------------+
|  G  | ηTM < 85         |
+-----+------------------+

Now let’s look at the same three examples from above to compare their energy label classes. Reminder: “eq.i.” shows the approximately equivalent incandescent lamp wattage. Row “Class” shows the new energy label class while row “Old” shows the class of the old scale we calculated above.

+-------+---------+--------+--------+
| Type  | LED     | LED    | incand.|
+-------+---------+--------+--------+
| eq.i. | 100 W   | 40 W   | 40 W   |
+-------+---------+--------+--------+
| P-on  | 11 W    | 4.5 W  | 40 W   |
+-------+---------+--------+--------+
| Φ-use | 1521 lm | 470 lm | 443 lm |
+-------+---------+--------+--------+
| ηTM   | 138     | 104    | 11     |
+-------+---------+--------+--------+
| Class | D       | F      | G      |
+-------+---------+--------+--------+
| Old   | A++     | A++    | E      |
+-------+---------+--------+--------+

When comparing the old and the new classifications you can see that the old A++ class ranges through almost the whole spectrum of the new energy classes while the new class G includes lamps from many previous non-A++ classes. So the focus and the “fine granularity” of the new scale clearly shifted to more efficient lamps.

Calculator

LED-to-Bulb converter is an Android app (written by me, the author of this article) helping users to better estimate the brightness of LED bulbs, CFLs, and halogen lamps by comparing them to classic incandescent light bulbs. Now, while writing this article, I extended the app with an EU Energy Label section which applies the formulas discussed in this article and compares the old and new scales.

The app is available for free on Google Play and Amazon but shows ads in the free version as a small compensation for my efforts.

Conclusion

In this article, we compared the old EU Energy Label with the new EU energy label which will be mandatory for light sources starting from September 2021.

The new EU energy label scale’s focus shifted to more efficient light sources to take recent technological advancement in the sector of efficient LED lamps into account.

Calculation of the new energy label was simplified compared to the old label and is — for simple cases, i.e. light bulb-type lamps — calculated by dividing a lamp’s luminous flux (Lumen) by its power consumption (Watt) and mapping the result to one of the seven categories (A to G).

About me: I am an Austrian software developer who writes mostly about tech-related topics. Find more of my projects on mickbitsoftware.com.