Lux is the unit of illuminance, or the amount of light that hits reaches a surface. The number of lumens ( = light output of the light source) per square meter is the lux value. For private use, the lighting of your living room, 300 tot 500 lux is average.
The standard for workplace lighting according to NEN-EN 12464-1:2011
Workplace lighting –Part 1: Indoor workplaces. This standard is a 25 pages appendices stating the required illuminance, light distribution, reflectance and colour rendering index for each type of task.
Task area: The surface where the eye task is performed. In addition to the lighting requirements for task areas and the immediate surroundings, minimum requirements are also set for the lighting level in the rest of the room. We call this area the backgrond area.
It is important to properly illuminate the entire space in which people are located. The aim is to enable good visual communication between people. For the visual experience and comfort it is important that het environment, the colours of the objects and the skin of people are displayed in a natural way.
For the colour rendering index (RA) the standard sets a minimum requirement for almost all task spaces:
Average working spaces > 80 Ra
Workspaces with higher eye task require > 90 Ra.
Daylight: The use of daylight lamps is encouraged in the standard, but not prescribed. The use of daylight lamps provides benefits for people who work indoors. The NEN-EN 12464-1 standard does not contain any requirements for the light colour.
Examples with minimum lux values.
Writing, typing, dataprocessing - 500 lux
CAD drawing - 500 lux
Front desk - 300 lux
Raw - 200 lux
Mediocre - 300 lux
Nice - 500 lux
Precision - 750 lux
Ckassriin - 500 lux
Auditorium - 500 lux
Sports hall- 300 lux
Kitchen - 500 lux
Stairs - 150 lux
Library reading area - 500 lux
Art-oriented training - 750 lux
Technical courses - 750 lux
Examination / treatment room - 1000 lux
Operating room - 1000 lux
Dental surgery room - 5000 lux
Autopsy tables- morgue - 5000 lux
Dermatalogie/ dialyses - 500 lux
Therapy/ massage/endoscopy - 300 lux
Waiting zone - 200 lux
Self service restaurant - 200 lux
Buffet - 300 lux
Conference rooms - 500 lux
Kitchens - 500 lux
Theaters, cinemas, concert halls - 300 lux
Changing rooms, rehearsal rooms - 300 lux
Sell fairs - 300 lux
Production ceramics, glass, ect - 500 lux
Handicraft ceramics, glass ect - 1000 lux
Optical glass work - 1000 lux
Food processing industry - 500 lux
Textile processing industry - 1000 lux
Automotive industry, paint shops, garages - 1000 lux
Wood processing indystry, ( selection and processing) - 750 lux
All types of quality controls - 1000-1500 lux
Colour determination, colour inspection - 1000 lux
Control tower - 500 lux
Hangars - 500 lux
Customs - 500 lux
Watchmaker - 1500 lux
Tailor - 1000 lux
Goldsmith - 1000 lux
Leatherworker - 500 lux
Shoemaker- 500 lux
Barber - 500 lux
Bookbinder - 500 lux
For each lighting installation, a mainenance schedule must be drawn up with replacement intervals of the light sources and the cleaning times of luminaires and the room. The specified minimum illuminance values are based on good maintenance and must be achieved in all circumstances. The major manufactures have had the maintenance factor calculatedfor different types of lamps, luminaires environment, replacement and maintenance schedules. With a maintenance factor of 0.85, the lighting in an office will have to deliver 588 lux in order to alway meet the minimum value of 500 lux.
Cylindrical lighting and modeling.
To ensure visual communication and recognition of objects / faces, the term " cylindrical lighting" has been included in the standard. This is the illuminance from the four directions (360° )at the seat height (1m20) or standing height (1m60). The minimum value is 50 Lux with an uniformity of more than 0,1. In an office where good viual communication is important, a minimum of 200 Lux is required.
Modeling expresses the relationship between this cylindrical and direct lighting. The ratio is best between 0.3 en 0.6.
Even light distribution ( U).
The light should be evenly distributed. This is expressed by the uniformity or ratio between the lowest and average illuminance within a zone. Depending on the visual task, this uniformity is at least between 0,4 en 0,7 in the task area.
A minimum value of 0.4 applies to the immediate vicinity to ensure uniformity and a minimum value of 0.1 for the background. This means that in the spacious environment the ratio between the illuminance in the task area and the lowest value in the spacious environment may not exceed 10:1.
Another factor that helps to distribute the light is a minimal reflection value of the large surfaces in the rooms such as the cieling, walls, floor and objects (furniture).
Surface Reflection value:
Ceiling 0.7 – 0.9
Wall 0.7 – 0.9
Floor 0.2 – 0.4
Large objects 0.2 – 0.7
In order to reflect light into a room, light must first reflect on these surfaces. Minimum illuminances for the walls ( 50 lux) and the ceiling ( 30 lux) have also been included for this. For closed spaces such as an office, education and health care, corridors,....the minima are even higher ( 75 and 50 lux for walls and ceiling, respectively).
Glare occurs when a certain area has a greater brightness than the rest in the field of view. This van be directly or indirectly through reflection. The degree of glare, UGR or Unified Glare Rating, is given an important place in the standard. This is a measure of glare from the luminaires and is described for each type of tasks. The scale ranges from 10 to 28, the lower value the less the glare. Daylight from outside or unshielded light sources in the viewing direction can also provide direct glare. Brightness control can dim daylight. For lamps, the minimum shield angle is expressed in the table below.
Luminance lamps kcd/m2/ shielding angle:
20 – 50 15°
50 – 500 20°
> 500 30°
Glare from reflection can be prevented by:
* matte wall covering
* large luminaires
* light ceilings and walls
* correct placement of luminaires with low luminance
EN12464-1 also determines the maximum brightness or luminance of luminaires in function of the quality of the screen. The basis for this is the ISO 9214-307. Different values apply to shiny screens or shielded screens in production.