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How do I read the energy label of a light bulb?

From now on the packaging of all light bulbs has to include an “energy label”. This label indicates the following properties of the bulb:

  • energy efficiency (letter of the alphabet): there are seven categories, from A (the most efficient bulbs) to G (the least efficient bulbs);
  • light output (in lumens): the figure to check in order to find out how much light the bulb gives off;
  • power (in watts) ;
  • lifespan (in hours): note that a bulb is used on average for 1,000 hours per year (about three hours per day).

The packaging also provides other useful information about the light bulb, such as its size, the colour of the light, its start time, etc

A label and a number of promises

Initially, the energy label was introduced by the European Union to classify household electrical appliances. Today it is used in more and more fields: electric light bulbs, television sets, buildings (EPB certificate) , cars, etc. The aim is to enable you to give preference to appliances that use less energy and that will cost less during their lifespan.

Information on the energy label…

How do I read the energy label of a light bulb?

View this image in large.

The most visible information, because of its large lettering and the grading of the colours, is the energy class of the bulb. The best bulbs are those in class A, the least good in class G. In other words: A-class bulbs are the most efficient because they use less energy than the others to supply the same amount of light.

Typically, light bulbs are devided into categories (1):  

  • Compact fluorescent light bulbs are in category A or B.
  • Halogen bulbs are in category D
  • Incandescent bulbs are in category E or F.

Beneath the energy category, you will see three figures and three units:

  • in lumens (lm), the quantity of light (2) emitted by the bulb: the higher the figure, the more light the bulb emits for the same electricity consumption. So don’t depend on watts when choosing your bulb, but on lumens! To help  you, note that a 110 W incandescent bulb emitted 1300-1400 lm while a 25 W bulb emitted 220-230 lm;
  • in watts (W), the electrical power absorbed (3). This gives an indication of consumption: the more powerful a bulb, the more electricity it uses. For instance, a 13 W light bulb will use 0.013 kWh (kilowatt hours) every hour.
  • in hours (h), the lifespan (4): bear in mind that 1,000 hours corresponds to about one year’s use;

In addition to the energy label, the light bulb packaging includes other information that will help you choose:

  • in millimetres (mm), the size of the bulb (5): both the length (including the base) and the diameter are given. This means you can be sure that the bulb is suited to your light fitting;
  • in kelvins (K), the “colour temperature” (6): it tells you the colour of the light. A low temperature (less than 4 000 K) indicates a warm light. A high temperature (over 5,300 K) indicates a cold light;
  • in seconds (sec.), the start time (7): this is the time it takes the bulb to reach 60 % of its light output.
  • the number of times the bulb can be switched on or off (8);
  • the capacity of the bulb to work with a dimmer switch (9).

What about ecological criteria?

While the energy label tells you about the energy performance of the light bulb you have bought, it does not say anything about its impact on the environment.  You will find out a little more by checking whether the bulb carries an ecolabel (a blue and green flower with star-shaped petals).

This European label guarantees products that have less of an impact on the environment and which are safe and reliable to use.  N.B.: This labelling is voluntary, which means that the product fulfils the ecological criteria set but is not necessarily the most environmentally friendly on the market (other products that do not carry the label may be equally or even more environmentally friendly).

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