People spend most of their lives indoors, so the choice of artificial lighting is as important as a suitable indoor microclimate.

We have been able to use electricity for over a century, not only to operate different electrical appliances, but also to illuminate housing. Engineers have continually sought to make artificial lighting technologies more efficient and safer. If candlelight and oil lamps were initially replaced by incandescent bulbs, then today we have light-emitting diode, or LED technology, which is 10 times more efficient, to replace usual incandescent bulbs.

Lighting is one of major consumers of energy in the home, so choosing the most energy efficient solutions is particularly important. Currently, the most energy efficient light bulbs are LEDs. Taking into account all the benefits of LED bulbs, they are the best choice for reducing power consumption and overall costs.

How to navigate the instructions shown on the light bulb package?

To select an appropriate bulb, a number of essential parameters on the bulb packaging should be considered. The key characteristics of a light bulb are also shown on the bulb package. An explanation of the bulb pictograms can be found below.


Light bulb pictograms

1. Energy efficiency labels

From September 1, 2021, A is the highest energy efficiency class, while G is the lowest.

A class bulb has the longest operating time and the lowest power consumption.

The power consumption of the bulb in kilowatt hours (kWh) for 1,000 hours is indicated on the bottom of the label.

2. Luminous flux

The luminosity of a light bulb is characterised by the luminous flux, with the lumen (lm) as the unit of measurement. The higher the lumen, the brighter the bulb shines.

For example, a 60 W incandescent bulb can be replaced with a 702 lm halogen bulb, a 741 lm compact fluorescent bulb or a 806 lm LED bulb, but the light that is perceived by the human eye will be the same.

3. Power

The unit of power of the bulb is watts (W).

To calculate the daily, monthly or annual electricity consumption of a bulb in kilowatt-hours (kWh), the power (W) must be divided by 1,000 and multiplied by the bulb’s service life in hours (h).

4. Colour temperature

The colour temperature of light bulbs is measured in degrees Kelvin and designated by K. The lower the degrees Kelvin, the more yellow the light, whereas the higher the degrees Kelvin, the more blueish the light.

The light emitted by bulbs tends to be different: yellow, white or bluish. The warm white light is in the range from 2,700 to 3,200 K, white light – from 3,200 to 4,000 K, bluish white light is more than 4,000 K and bluish light is over 6 000 K.

More yellow light is advisable for living space, while white light is suitable for workrooms and corridors.

5. Colour rendering index

The colour rendering index is designated by Ra and it represents the colour rendering of the object in the light of the bulb compared to the same colours in the daylight.

The closer Ra is to 100, the more precise the object’s colour in the light of the bulb.

6. Number of switching cycles

In places where lighting has to be switched on or off frequently, bulbs with more switching cycles should be used.

6,000 switching cycles are most commonly indicated of the packaging of compact fluorescent bulbs, while LED bulbs have from 20,000 to 200,000 cycles.

7. Service life

The bulb’s service life forecast by the manufacturer is given in hours (h); however, at least 50% of bulbs also operate after exceeding the specified time.

8. Warm-up time

This indicates the time in which the bulb will reach a 100% light output – whether it will happen gradually or with a delay of 1 second, or in any other time unit.

9. Bulb and bulb socket size

When purchasing a new bulb, pay attention to the bulb socket type, bulb size and light emitting angle. Therefore, it is recommended to take a burnt out bulb with you to the shop.

It is important not only to select the most suitable and energy efficient bulbs, but also to develop a well-considered lighting system. See below the recommendations for optimal arrangement of luminaires in different rooms.

Recommendations for the arrangement of luminaires


  • In the kitchen, the correct arrangement of luminaires is particularly important, since action in this room takes place in several areas.
  • Lighting must be sufficiently bright and focused on working surfaces. One of the solutions is the placement of lighting under cabinets hanging above the working surface.
  • It is important that the light source is not located behind the person’s back, as it may cast a shadow on the working surface.


  • In the bedroom, you need to choose dimmed central lighting and additional luminaires for certain zones.
  • The light from the luminaire on the ceiling disperses light in all directions and therefore does not look so bright.
  • Brighter lighting can be selected for the wardrobe, dressing table and reading.
  • The bedside lamp with an adjustable flux of light will be comfortable for reading and will not disturb the person sleeping near you. Since we are staying in the bedroom in the morning and evening, it is recommended that we choose warm white light bulbs for this room (2700-3000 K), which will allow the body to wake up slowly and create a relaxing mood in the evening.


  • Due to increased humidity, it is recommended to select lamps with closed shades.
  • It is desirable to illuminate the mirror separately, preferably from the top and sides.
  • If the toilet is combined with the bathroom and the family is large, then the lighting is likely to be frequently switched on and off. In such cases, you can consider installation of a motion sensor and select bulbs with higher switching capacity.
  • If a bath is planned to be constructed/installed, it is recommended that relaxing lighting be provided with a warmer light colour and a lower light intensity.
  • In the bathroom, it is recommended that you select white lamps (3200-4000 K) that will cheer up and allow you to prepare for a fruitful day. On the other hand, if you want to create two different moods in the bathroom, it is recommended that you choose bulbs that can be switched with a regular switch – suitable for relaxing evening rituals.

Living room

  • Lighting must be designed at several levels and with the possibility to adjust its intensity.  This will make it easy to do all the usual things – watch favourite TV shows, read books, work, play table games, etc.
  • The farther the luminaire is from the floor or tabletop, the more the light emitted by the bulb disperses. Therefore, rooms with high ceilings require a light source with higher intensity/flux or more lumen.
  • In the living room, it is recommended to select bulbs with warm white light (2700-3000 K) and to install lighting intensity regulators or dimmers.

The energy efficient lighting system, of course, includes LED lamps, but significant reductions in electricity/energy consumption can also be achieved by the installation of different lighting regulation devices. The most common of them are:

Lighting regulation

Light intensity regulator (dimmer)

  • Special switch, mobile app, or built-in mechanism in a bulb that allows you to change the brightness of the bulb as needed, while also reducing electricity/energy consumption.

Motion sensor

  • A variety of motion sensors that are able not only to respond to motion but also to keep the lighting on while a person is in the room are available today.
  • Today, there are also bulbs that already have built-in motion sensors. This allows using the motion sensor functionality without installing a separate sensor.

Twilight sensors

  • Suitable for regulation of outdoor lighting.
  • Ensure that the lighting is switched on when it becomes dark.

Lighting level sensors

  • This type of sensor allows the operation of luminaires to be regulated depending on the level of the natural lighting in the room.
  • When the required level of illumination is provided by sunlight, the artificial lighting is switched off.

Light colour regulation

  • The sun is a perfect luminaire, the light colour of which varies significantly depending on the time of day.
  • For example, it is yellowish (warm white) in the morning and evening, while the light is cold white in the middle of the day.
  • It is also possible to adapt light bulbs to this principle that will ensure that the natural daylight cycle is followed when you stay indoors.

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