Guide Technique Lux (lx)

Lighting Guide | Lux (Illuminance)

What is Lux (lx)?

What is Lux (lx)?

Lux (lx) quantifies illuminance, which is the amount of light (luminous flux) that falls on a given surface. One lux is equal to one lumen per square meter (1lx = 1lumen/m²). In other words, it quantifies how brightly a surface is illuminated.

Think of a light bulb shining in a room. The total light it gives off is measured in lumens. Now, imagine focusing a portion of that light shining onto a table. The concentration of light on that specific area or surface is what we describe as lux. In other words, while lumens tell you how bright a light source is, lux tells you how brightly an area will be illuminated by that source.


How to chose the right light source for enough illuminance

If you want to achieve a certain lux level in your living room (e.g., 300 lx), several factors come into play. Here's a step-by-step guide to help you choose the right light source:

  1. Calculate the room's size in square meters.
  2. Determine the total lumens required. Multiply the desired lux level by the room's area to find out the total lumens you'll need. For instance, if your living room is 20 m² and you want 300 lx:
    20 m² × 300 lx = 6000 lumens.
  3. Factor in the room's color and reflectivity.
  4. Use multiple light sources for even distribution. A single central light source may not distribute light evenly across the room. Using multiple light sources or fixtures (pendant, table lamp, floor lamp,..) can help distribute light more evenly.
  5. Check bulbs for their lumens rating.
  6. Keep in mind that lux decreases as light travels further from its source. Ceiling height and the positioning of wall lights, therefore, play a role.
  7. Account for any natural light in the room and consider the time of day you'll mostly be using the room.
  8. Opt for dimmable bulbs to adjust brightness as needed.

In essence, achieving the right lux involves considering room size, bulb lumens, room decor, light placement, and natural light. It's often an iterative process, where you might need to test and adjust until you get the desired illumination.

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Lux in residential settings

In residential settings, lux measurements serve as guidelines rather than strict standards. This is because people have diverse preferences based on their activities, comfort, and aesthetic choices. However, understanding these values can help you achieve effective and efficient lighting:

  • Hallways: around 100 lx
  • Kitchens: between 300-500 lx
  • Offices: between 300-500 lx
  • Living Rooms: around 300 lx

Remember, these are just guidelines. While some people might prefer brighter spaces, others might lean towards a more subdued, atmospheric setting. Using dimmers can be a great way to adjust and customize lighting according to individual preferences and needs.

In reference to natural light, under a full moon, we obtain 0.25 lx; by day, under an overcast sky, 5000 lx and under full summer sun, 100,000 lx!

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