Calculation of Illuminance
In practice, illuminance is measured with a lux meter, but it can also be calculated by dividing the luminous flux (Φ) by the illuminated area (A):Good to know: According to the inverse square law, illuminance decreases the farther you move away from the light source. Specifically, if the distance to the light source is doubled, the brightness is reduced to a quarter.
Standards and Regulations
Standards and regulations for illuminance are important guidelines that determine how bright different work and living areas should be lit to ensure safety, health, and comfort. In Germany, for example, DIN EN 12464-1 for indoor spaces and DIN EN 12464-2 for outdoor areas set minimum requirements for illuminance. These standards regulate how much light is needed in various environments, such as offices, workshops, or streets. The requirements depend on the type of activity: Fine work, for example, requires higher illuminance than rough work. Additionally, factors such as glare, shadow formation, and light color are taken into account to ensure optimal visual conditions. Such regulations help prevent accidents, improve productivity, and enhance people's well-being.10 Examples of Minimum Illuminance Requirements for Activities, Workplaces, Workrooms, and Areas:
| Activities, Workplaces, Workrooms, and Areas | Minimum Illuminance E |
|---|---|
| Open-pit mining: Orientation lighting | 3 lx |
| Storage: Storage rooms for uniform or large goods | 50 lx |
| Traffic routes: Stairs, escalators, moving walkways, elevators | 100 lx |
| General: Canteens, tea kitchens, self-service restaurants | 200 lx |
| Office: Filing, copying | 300 lx |
| Office: Writing, reading, data processing | 500 lx |
| Office: Technical drawing (hand drawing) | 750 lx |
| Electrical industry: Very fine assembly work | 1000 lx |
| Jewelry making: Gemstone processing | 1500 lx |
| Printing: Steel and copper engraving | 2000 lx |