What do the terms lux and lumen mean?

Basic information about lighting

measurement

If you've ever bought a lamp, you've probably heard the term "lux." But what exactly does this term mean? In this article, you'll learn everything you need to know about lux and lighting measurements. When it comes to lighting, it's not just the design of the lamp that plays an important role, but also the properties of the light itself.

However, there are countless units of measurement to consider – one of which is illuminance. It is measured in lux, abbreviated lx, which comes from Latin and can be translated as light. In this article, we will explain exactly what this means.

Illuminance is expressed in the physical unit lux and represents how much light or luminous flux falls on a given area. However, this is not the same as brightness, as a white wall, for example, appears much brighter than a dark area with the same illuminance. The color of the surface therefore has an enormous influence on our perception of brightness.

Illuminance is important to ensure that we have enough light to perform our daily tasks. Too little light can cause eye strain and headaches, while too much light can be dazzling. Lux is also important to ensure that we have the right type of lighting for our needs. For example, a workspace requires more lighting than a living room.

Lux can be measured with a lux meter, which usually consists of a light sensor and a display device. The light sensor picks up the incident light and the display device shows the illuminance in lux. There are also apps for smartphones that can measure illuminance, but they are usually not as accurate as a lux meter. We recommend different illuminance levels depending on the room: In our opinion, an illuminance level of 100-200 lux is suitable for the living room. In contrast, 300 to 500 lux is more suitable for the office. In surgery, a guideline value of 5000 lux should be used.

If you want to make sure you have enough light for your needs, you can

use

You will not find this information on the packaging of the luminaire or light source. You will have to calculate the illuminance of a lamp yourself, as this depends heavily on the positioning of the luminaire: if it is mounted very close to a surface, the lux value will be significantly higher than if the light source is very far away from the surface.

Illuminance is now defined as lumens per square meter (lm/m²) and is measured with a so-called lux meter on horizontal and vertical surfaces or using simulations. In addition to the distance of the luminaire from the surface and the lumen value, the beam angle of the lamp is also required to ultimately determine the exact number of lux.

"When buying lights, you should make sure that the illuminance is appropriate for the room. Use warm light in living areas and cooler light in work areas. Smart lamps offer a flexible and adaptable lighting option."

The importance of the terms lux and

lumen

Lux and lumen are both units of measurement that play an important role in the lighting of rooms and buildings. While the lumen describes the amount of light emitted by a light source, the lux indicates how much light falls on a specific area. When purchasing lights for indoor or outdoor use, it is important to consider both the lumen and lux values. A lamp with a high lumen value does not always equate to good lighting.

A high lumen value simply means that the lamp emits a lot of light. However, brightness is influenced by the size of the room and the height of the lamp. For example, a room with a high ceiling requires a higher lumen count to be adequately lit. The lux value is an important factor for the illuminance in a room.

To determine the correct illuminance for a room, various factors such as the size of the room, the ceiling height, and the type of activities that take place in the room must be taken into account. For example, a workspace or kitchen counter requires higher illuminance than a living room.

Choosing the right lighting is not only about considering the right lux and lumen values, but also the color temperature and color rendering index (CRI) of the light source. Color temperature is measured in Kelvin (K) and influences the atmosphere of the room.

Warm white light (2700K-3000K) creates a cozy atmosphere, while cooler light (5000K-6500K) is better suited for work areas.

The CRI is a measure of a light source's ability to reproduce colors accurately. A high CRI is particularly important in rooms such as bathrooms, where makeup is applied, or in art studios, where color rendering is important. Another important consideration when choosing lighting is energy consumption.

Lights that use LED technology typically have lower energy consumption than traditional incandescent or halogen bulbs. LED lights also have a longer lifespan and are more environmentally friendly, as they consume less energy and produce less waste

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When installing lights, it is important to follow safety regulations. Electrical installation should be carried out by a professional to avoid electric shocks or fires. The lights should also be installed in places where they cannot be accidentally damaged, such as near doors or windows. 

Important photometric quantities

• Lumen: how much light a light source emits per second in total
• Luminous intensity (candela): indicates the current relative to the solid angle
• Illuminance lux: luminous flux that strikes a specific surface
• Luminance: provides detailed information about the luminous flux emitted

What else do I need to consider when it comes to living room lighting?

Illuminance in lux is less relevant for private individuals and more relevant for commercial and public spaces, as certain regulations apply here. These regulations serve to ensure occupational safety and personal safety and should therefore be observed:

• Workplace lighting: min. 500 lux (the more detailed the activity, the more)

• Traffic zone lighting: 100 lux

• Street lighting: 10 lux

• Escape route lighting: min. 1 lux in the center

However, you can also use these guidelines for your private rooms. Nevertheless, it makes more sense to focus on the luminous flux and the beam angle in order to roughly estimate the illuminance when making a purchase. After all, this is not simply stated and requires a calculation first.

• Bedroom: 45 lux

• Living room: 77 lux

• Bathroom: 110 lux

Conclusion – How to do everything right!

Overall, choosing the right lighting is an important factor in the functionality and atmosphere of a room. Considering lux, lumens, color temperature, and CRI when selecting lights can help you find the best lighting solution for the room.

Current lighting trends, such as the use of decorative lights and smart lamps, offer additional options for improving the lighting in a room.

If you are still undecided about how you want to implement lighting in your home,feel free to make an appointment with the lighting professionals at skapetze® for a personal consultation and the development of an individuallighting concept.

You are also welcome to visit us at our lighting studio in Simbach am Inn.

If you already have a specific idea of what you want the lighting in your living room to look like, we can help you turn that idea into reality—our in-house workshop makes it possible.