Kelvin.

The higher the number, the colder the light. 2,700-3,000 Kelvin is warm light, produced by filament and halogen bulbs – ideal in your living room. 3,500-4,000 Kelvin gives a whiter light, similar to daylight – ideal for your bathroom.

Lifetime (h = hours).

A light source is typically used for three hours a day, 1,000 hours a year.

Watt, W.

Was the designation used for old filament bulbs. Now that energy-saving bulbs have taken over, lumen is the unit we use.

Socket Size.

Small socket: E14, and large socket: E27.

Lumen.

A term for luminous flux, or the amount of light emitted from a bulb. When you choose a bulb based on lumen, you should note that the luminous flux will decline slightly with time. This applies to all types of bulb. However, since energy efficient bulbs have a much longer lifetime than filament bulbs, this is a factor you need to consider when you buy. For this reason, you should always choose a lumen value that is higher than your actual requirement.

Ra Value (CRI).

The ability of the light source to represent colours correctly in relation to optimal sunlight, which has an Ra value of 100. It is more important to consider Ra value in the kitchen or bathroom, for example, than in a corridor or utility room.

Light with an Ra value of more than 90 is referred to as realistic light. However, this should not be confused with ‘daylight’ which refers to the actual colour of the light (Kelvin). In fact, daylight is almost blue. At 2,700 Kelvin, the light colour of conventional bulbs is golden. Daylight colours are anything above 5,000 Kelvin.

Dimming.

The symbols indicate whether the light source can be used with a dimmer or not.

Energy label.

Best choice: LED: A
From the 1. September 2021 the energy labeling changed and light sources are now rated from A till G. This change also means that it is only mandatory to make energy labels for lamps with a built-in LED light.